POLITECNICO DI MILANO ANALISI E SVILUPPO DI SISTEMI

POLITECNICO DI MILANO
Facoltà di Ingegneria Industriale
Tesi di Laurea in
Ingegneria Meccanica - Impianti e Produzione
ANALISI E SVILUPPO DI SISTEMI
MANUTENTIVI BASATI
SULL’E-LEARNING
CASO APPLICATIVO: METOLOGIA FMECA
TRAMITE IL SOFTWARE PROMIS
!
RELATORE
CANDIDATO
Prof. GARETTI Marco
Randazzo Francesco
Dipartimento di Ingegneria Meccanica
Matricola 752502
ANNO ACCADEMICO 2013 – 2014
INTRODUZIONE
3
1! DALLA FORMAZIONE TRADIZIONALE ALL’ E-LEARNING!
6!
1.1! METODOLOGIA DI FORMAZIONE TRADIZIONALE!
1.1.1! I!COSTI!DELLA!FORMAZIONE!TRADIZIONALE!
1.2! METODOLOGIA DI FORMAZIONE TRAMITE E-LEARNING!
1.2.1! EVOLUZIONE!DELLA!FORMAZIONE!A!DISTANZA!(FAD)!
1.2.2! PASSAGGIO!DA!FORMAZIONE!A!DISTANZA!(FAD)!A!E:LEARNING!
1.2.3! L’E-LEARNING!
1.2.4! FORMAZIONE!IN!RETE:!PRINCIPI!DI!FONDO!
1.2.5! E:LEARNING!NEL!PANORAMA!ATTUALE!
1.2.6! LE!PRINCIPALI!NECESSITÀ!DELLE!AZIENDE!ITALIANE!LEGATE!ALLA!FORMAZIONE!
8!
8!
9!
11!
13!
14!
15!
18!
19!
2! SOFTWARE PROMIS!
20!
2.1!
2.2!
2.3!
2.4!
2.5!
2.6!
2.7!
21!
22!
25!
26!
28!
29!
30!
VISIONE D’INSIEME!
METODOLOGIA!
REQUISITI LEGALI E STANDARD!
GESTIONE DELLA QUALITÀ!
GESTIONE AMBIENTALE!
SALUTE SUL LAVORO E GESTIONE DELLA SICUREZZA!
L’APPROCCIO INTEGRATO!
3! METODOLOGIA FMECA!
33!
3.1! INTRODUZIONE!
3.2! FMECA E FMEA!
3.3! TERMINOLOGIA!
3.4! METODOLOGIA!
3.4.1! SCOMPOSIZIONE DELL’ENTITÀ.!
3.4.2! LIVELLI!DI!SCOMPOSIZIONE!DI!UN’ENTITÀ!
3.4.3! SELEZIONE!DELLE!ENTITÀ!CRITICHE!
3.4.4! INDIVIDUAZIONE!DEI!MODI,!DEI!MECCANISMI!E!DELLE!CAUSE!DI!GUASTO.!
3.4.5! INDIVIDUAZIONE!DEGLI!EFFETTI!DEL!GUASTO!
3.4.6! INDIVIDUAZIONE!DEI!SINTOMI!DI!GUASTO!E!DEI!METODI!DI!RILEVAZIONE!
3.4.7! ANALISI DELLE CRITICITÀ!
3.4.8! INDIVIDUAZIONE!DELLE!AZIONI!CORRETTIVE!
3.4.9! PIANIFICAZIONE!DELLA!MANUTENZIONE!
3.5! FMECA: BENEFICI E PUNTI DEBOLI!
33!
33!
34!
35!
35!
36!
37!
38!
39!
39!
40!
45!
45!
46!
4! FMECA CON PROMIS!
48!
4.1! TIPOLOGIE DI FMECA E CAMPI DI APPLICAZIONE!
4.2! SVILUPPO METODOLOGIA FMECA UTILIZZANDO IL SOFTWARE PROMIS!
4.3! DESIGN FMECA!
4.3.1! METHODOLOGY!
4.3.1.1! Introduction!
48!
51!
53!
53!
54!
!
2!
4.3.1.2! Preparation!
4.3.1.3! FMECA Procedure!
4.3.1.4! Filling Worksheet!
4.3.1.5! Risk Analysis!
4.3.2! INSIGHTS!
4.3.2.1! Terminology!
4.3.2.2! Analisi di Pareto!
4.3.2.3! Fault Tree Analysis!
4.3.2.4! FMECA Forms!
4.3.2.5! More about risk Analysis!
4.3.3! TEMPLATES,!SCALES!AND!CHECKLISTS!
4.3.3.1! Preparation Checklists!
4.3.3.2! FMECA Procedure Checklists!
4.3.3.3! Filling Worksheet Template and Scales!
4.3.3.4! More about Recommended Actions!
4.4! MACHINERY FMECA!
4.5! MORE INFORMATION!
4.5.1! BIBLIOGRAFIA!
4.5.2! ARTICOLI!
4.5.3! LINEE GUIDA!
4.5.4! STANDARD!
4.5.5! SOFTWARE!
56!
59!
61!
62!
64!
64!
65!
66!
66!
67!
68!
68!
69!
69!
70!
71!
72!
73!
74!
75!
77!
78!
5! CONCLUSIONI E SVILUPPI FUTURI!
79!
ALLEGATI!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!82!
!
3!
Introduzione
L'e-learning è una metodologia didattica che offre la possibilità di erogare
contenuti formativi elettronicamente, attraverso Internet o reti Intranet (ASFOR,
2003).
Per l'utente rappresenta una soluzione di apprendimento flessibile, in quanto
fortemente personalizzabile e facilmente accessibile. L'utilizzo sistematico e
diffuso di tecnologie sempre più performanti e l'evolversi dei bisogni di
apprendimento individuali e organizzativi, hanno recentemente condotto alla
diffusione su ampia scala dell’e-learning raggiungendo numerosi settori tra i
quali la manutenzione industriale
Le aspettative del mercato e le normative applicabili ai prodotti cambiano
rapidamente; gli stessi prodotti e le tecnologie di produzione cambiano ad un
ritmo vertiginoso, nuovi prodotti vengono immessi sul mercato con la frenesia
di arrivare per primi.
Spesso la fretta porta a prendere delle decisioni senza considerare in modo
adeguato i rischi connessi: il bisogno nell’industria di una tecnica disciplinata e
interdisciplinare, per identificare e prevenire problemi potenziali, è ora più
importante che mai.
Applicata per la prima volta il 9 novembre 1949 negli USA all’interno di una
military procedure, nella sua più rigorosa concezione, la FMECA (Failure
Mode, Effect and Criticality Analysis) è un riepilogo dei pensieri di un tecnico
di progettazione o di processo nel momento in cui si attiva per
l’industrializzazione di un prodotto includendo nei suoi pensieri l’analisi di ogni
concepibile ma realistica, “cosa” che potrebbe andar “male”, basandosi
sull’esperienza e sui problemi passati.
L’approccio sistematico indicato dalla tecnica FMECA guida e formalizza
l’orientamento mentale che ogni tecnico normalmente ha durante il processo di
sviluppo e messa punto di un processo produttivo. La FMEA è una tecnica
analitica utilizzata come mezzo per assicurarsi che ogni concepibile potenziale
modo di guasto sia considerato e analizzato.
Lo scopo di questa tesi è dunque, di dimostrare l’applicabilità dell’e-learning in
ambito manutentivo e, in particolare, alla metodologia FMECA.
Nel primo capitolo è presentata una panoramica sull’e-learning, in cui vengono
esposti i principali punti di forza che ne stanno favorendo la sempre crescente
diffusione.
!
4!
Nel secondo capitolo è presentato un software (PROMIS) e-learning utilizzato
per la gestione dei contenuti didattici.
Nel terzo capitolo viene fatta un’analisi dettagliata della FMECA dal punto di
vista teorico e le linee guida necessarie per l’applicazione di questo strumento
nell’ambito della manutenzione industriale. Una corretta comprensione dei
concetti teorici alla base della FMECA è, infatti, indispensabile per la buona
riuscita della stessa.
Nel quarto capitolo sono riportati tutti i passaggi della metodologia FMECA
sviluppata con il Software PROMIS. I contenuti completi possono essere
visualizzati nei vari allegati richiamati durante la trattazione.
Infine nel quinto capitolo si trovano le conclusioni e i possibili sviluppi futuri.
!
5!
1 Dalla formazione tradizionale all’ elearning
L’e-learning si è ormai confermato come uno dei trend più interessanti e
dinamici della formazione professionale e in grado di favorire la diffusione di
processi di innovazione sul territorio. Infatti, sempre più aziende e professionisti
in genere possono qualificare e aggiornare le competenze grazie alla velocità e
alla fruibilità dei sistemi di formazione telematici.
Una delle più rilevanti sfide per il mondo della formazione è dimostrare la
capacità di stare al passo con la rapidità alla quale l’informazione circola e
diviene obsoleta. L’aggiornamento immediato e affidabile delle conoscenze è
quindi una questione vitale, così come lo è la capacità di far fronte con estrema
flessibilità alle esigenze di un’organizzazione pubblica che cambia.
Il modello della formazione tradizionale e scolastica in base al quale si apprende
un mestiere che poi si esercita per tutta la vita, è stato sostituito dal modello
della formazione continua. L’attuale organizzazione del sistema formativo,
basato su strumenti e metodologie tradizionali, non è in grado di dare una
risposta soddisfacente a questo cambiamento. Chi lavora ha bisogno di soluzioni
flessibili che si adattino ai ritmi dell’attività di lavoro e dell’apprendimento: il
tempo sottratto al lavoro e i costi organizzativi hanno un ruolo sempre più
decisivo nelle scelte dei decisori e dei consumatori dei servizi formativi.
La Direttiva sulla formazione e la valorizzazione del Personale delle Pubbliche
Amministrazioni( 1 ) evidenzia che "I mutamenti organizzativi in atto,
l’introduzione di nuove tecnologie, l'esistenza di una rete nazionale e il
diffondersi del telelavoro debbono portare a ripensare i luoghi e le tecniche della
formazione. La progettazione delle attività formative, quindi, deve considerare
anche le diverse metodologie di formazione a distanza (videoconferenza, elearning) che permettono di assicurare l’efficienza e l’efficacia della
formazione." Inoltre, "L’adozione di tali tecnologie comporta notevoli
investimenti iniziali e, al pari di altri progetti di automazione, richiede un'attenta
pianificazione, soprattutto al fine di tenere conto degli obiettivi della
formazione, dei destinatari e dell'integrazione con le tradizionali metodologie
d'aula."
La Direttiva invita, quindi, gli enti di formazione pubblici a importanti
investimenti nel campo della formazione a distanza, delle nuove metodologie e
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
1
Direttiva del 13/12/2001 (G.U. n.26 del 31/1/2002), in particolare al punto 6. Le Nuove
Metodologie.
!
6!
tecnologie per garantire una risposta individuale alle esigenze formative e per
cambiare i luoghi e le modalità attraverso le quali si apprende.
In questo quadro diventa strategica una politica di investimento e ricerca nelle
metodologie e nelle tecnologie utili a favorire i processi di organizzazione della
conoscenza, di diffusione dell’informazione, di scambio di esperienze, di
produzione di contenuti e di supporto all’apprendimento.
Ripensare i luoghi e le tecniche della formazione in una logica di apprendimento
continuo richiede strumenti di comunicazione e condivisione che siano
contemporaneamente facili da utilizzare e capaci di gestire la complessità,
modulari e integrabili per le diverse esigenze, aperti e a basso costo per garantire
la massima diffusione. Sono necessari ambienti di lavoro e di apprendimento
integrati. Sul piano tecnologico questa integrazione è già in atto con la
progressiva convergenza di tre categorie di piattaforme informatiche:
•
content management, prevalentemente orientate alla redazione e
pubblicazione di contenuti informativi per il web;
•
learning management, per la ingegnerizzazione di contenuti formativi, la
erogazione di percorsi on line e l’apprendimento in rete;
•
knowledge management, per l’organizzazione
conoscenza individuale e sociale.
e
l’accesso
alla
•
Apprendimento personalizzato
Apprendimento
collaborativo
Knowledge
management
Esperienze
Apprendimento
assistito
Learning
management
Percorsi
Combinare
oggetti ,
percorsi
formativi e
scambio di
esperienze per la
formazione
continua in rete
Apprendimento
autonomo
Content
management
Oggetti
Figura'1.1'Differenti'tipologie'di'apprendimento.
!
7!
1.1 Metodologia di formazione tradizionale
1.1.1 I costi della formazione tradizionale
In generale, quando si parla di budget di formazione, il principale obiettivo è
quello di dimensionare un livello di costi compatibili con i criteri di economicità
di gestione.
Le principali voci di costo che possono caratterizzare un intervento formativo
sono:
• Consulenti esterni;
• Corsi e seminari esterni (iscrizioni di dipendenti di attività esterne svolte
da altri organismi come scuole, società di consulenza, università ecc.);
• Prestazioni dei docenti interni (formatori, tutor e testimoni aziendali);
• Logistica e residenzialità (affitto di aule o spazi, alberghi, spese di
trasferimento);
• Materiale didattico e attrezzature (documentazione, libri, audiovisivi,
attrezzature diverse per la didattica);
• Costi del mancato lavoro dei partecipanti;
• Costi generali del servizio di formazione.
Alla determinazione dei costi totali dell’intervento concorrono, per prima cosa, i
costi fissi, come ad esempio le spese di coordinamento e progettazione, la
remunerazione dei formatori e i costi di struttura relativi alla gestione ed al
funzionamento del centro di formazione. Mentre tra i costi variabili troviamo
quelli riguardanti i materiali, le voci di costo delle strutture didattiche utilizzate,
le spese di viaggio, di soggiorno o di trasferta relative alla permanenza dei
partecipanti presso il centro di formazione. Inoltre possiamo anche identificare
una principale voce di costo che non può essere attribuita ne ai costi fissi ne a
quelli variabili che è rappresentata dalla remunerazione del personale
considerato improduttivo durante la permanenza ai corsi.
È relativamente facile stimare l’incidenza dei costi variabili, attraverso la
determinazione del numero standard di partecipanti per ogni singola iniziativa
formativa. Allo stesso modo si possono stimare i costi di struttura, in relazione
ai tempi medi di formazione per unità del personale. Non è altrettanto facile
invece configurare il costo riguardante il personale distolto dallo svolgimento
della mansione di competenza. Tale costo rappresenta, infatti, la stima di un
rapporto costi/benefici che consente all’azienda di formare il maggior numero di
personale possibile, in relazione alle risorse disponibili nell’unità di formazione.
!
8!
Inoltre, per quanto riguarda i costi di coordinamento e progettazione, essi
possono avere un’incidenza più o meno accentuata in base al grado di
innovazione che si ritiene opportuno inserire nei programmi di formazione. E si
può dire altrettanto per i costi riguardanti i materiali e le metodologie didattiche
usate, che possono variare in relazione alla quantità e qualità di mezzi di
supporto e di accessori utilizzati nel processo formativo. Tali costi tendono ad
aumentare passando da corsi base ad iniziative specialistiche o a contenuto
manageriale.
Si può anche notare come influisca sui costi formativi l’organizzazione
territoriale dell’azienda divisa, che può presentare un elevato livello di
decentramento del lavoro o di accentramento, quando gran parte dell’attività
formativa viene svolta nella sede principale. Queste due ipotesi incidono in
maniera tutt’altro che indifferente sulla struttura dei costi di formazione.
Va ricordato, infine, che l’analisi dei costi della formazione presenta alcune
problematiche metodologiche quali:
•
•
•
Allocazione dei costi congiunti: si verifica, per esempio, quando la stessa
struttura viene utilizzata per più corsi di formazione, oppure sia per la
produzione sia per le attività formative.
Costi di nuovi (o vecchi) programmi di formazione: un nuovo
programma di formazione, di solito, richiede costi di ricerca e sviluppo,
di elaborazione di materiale didattico, di sperimentazione di nuove
tecniche, ecc. che devono essere ammortizzati per il numero di anni in
cui tale programma verrà offerto. È evidente che, in questi casi, le scelte
relative alle procedure di ammortamento e tasso di attualizzazione
possono avere un’influenza determinante nella quantificazione di questi
costi e, quindi, nel raffronto tra programmi vecchi e nuovi.
Valore della produzione dei formandi: può essere calcolato
confrontandolo con il tempo di produzione utilizzando manodopera
regolare e stimando, in tal modo, il tasso di sostituzione tra il tempo
necessario per formandi e quello per la manodopera regolare. Il salario
relativo viene, poi, applicato al tempo impiegato dai fomandi al netto del
tempo per la formazione in senso stretto, per i trasporti, le vacanze, ecc.
1.2 Metodologia di formazione tramite e-learning
• Definizione e-learning: Metodologia didattica che offre la possibilità di
erogare contenuti formativi elettronicamente (e-learning), attraverso reti
Internet o reti Intranet. Per l’utente rappresenta una soluzione di
!
9!
apprendimento flessibile, in quanto facilmente personalizzabile e
facilmente accessibile.
Il termine e-learning copre un’ampia serie di applicazioni e processi
formativi, quali computer based learning, Web-based learning e aule
virtuali. In effetti, sviluppare un sistema di e-learning significa
sviluppare un ambiente integrato di formazione utilizzando le tecnologie
di rete per progettare, distribuire, scegliere, gestire e ampliare le risorse
per l’apprendimento.
Tuttavia le definizioni che si possono trovare su questo argomento sono
numerosissime, ognuna delle quali inquadra l’argomento da sfaccettature
diverse. Per comprendere bene la definizione del concetto di e-learning
dobbiamo quindi esaminare l’evoluzione di quest’ ultimo nel corso degli anni.
Prendiamo ad esempio quella della commissione europea:!“l’utilizzo delle nuove
tecnologie multimediali e di Internet per migliorare la qualità
dell’apprendimento agevolando l’accesso a risorse e servizi nonché gli scambi e
la collaborazione a distanza“. Altrettanto degna di nota l’interpretazione di Kirk
Ramsay, esperto di istruzione e tecnologia presso la Scottish University for
Industry di Glasgow. Secondo Ramsay la “E” di E-learning dovrebbe essere
intesa come enablement, ovvero come uno strumento che consenta di ottenere
risultati migliori rispetto ad altre modalità formative. 2 Un ulteriore definizione
potrebbe essere questa: “E-learning è qualsiasi uso della tecnologia per
l’apprendimento al di fuori dei confini delle classi fisiche” 3.
Negli ultimi anni, le pubbliche amministrazioni europee hanno rinnovato e
rapidamente sviluppato un forte interesse verso le applicazioni alla formazione
delle nuove tecnologie dell’informazione e della comunicazione le quali
consentono di accelerare e ottimizzare la diffusione delle informazioni e della
conoscenza, abbattendo i vincoli di tempo e spazio.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2
Definizione
scritta
da
Kirk
Ramsay
reperibile
al
seguente
URL
http://www.vnulearning.com/archive/oln112001.htm
33
!
www.formes.com Online learning conference 2000
10!
Figura'1.2'Esempio'di'riduzione'dei'costi'tramite'un'programma'via'web'di'fornitura'di'piani'
di'manutenzione'con'supporto'di'tecnici'specializzati'che'ha'permesso'di'risparmiare'sui'
costi'di'gestione'di'un'CMMS'e'ha'permesso'di'acquisire'competenze'di'ingegneria'di'
manutenzione.
1.2.1 Evoluzione della Formazione a Distanza (FAD)
I primi casi di formazione a distanza (FAD) coincidono con la nascita dei corsi
per corrispondenza. In questa prima fase erano utilizzati soprattutto supporti
cartacei e il contatto tra docente e discente avveniva in maniera asincrona
attraverso una corrispondenza postale. Un ulteriore evoluzione a questo tipo di
approccio ha visto l’utilizzo di canali mediatici quali televisione e radio a
supporto del materiale cartaceo. Un notevole apporto multimediale alla
presentazione del materiale dei corsi si è avuto quando il CBT (Computer Based
Training), ovvero lo studio lo del computer come tecnologia didattica di
autoistruzione, è stato integrato al FAD. Le tradizionali dispense cartacee sono
state cosi sostituite dalla distribuzione di Cd-Rom contenenti il materiale
!
11!
informativo. Come già si può intuire la FAD è stata sempre integrata con le
evoluzioni tecnologiche nel campo della comunicazione. Sicuramente l’avvento
di Internet con il Word Wide Web e la diffusione sempre più ampia del suo
utilizzo hanno fatto sì che la formazione a distanza si evolvesse nuovamente. E’
proprio da questa evoluzione che nasce il WBT (web based training) e si
comincia a parlare di e-learning. La capacità della rete globale di trasmettere,
gestire e distribuire le informazioni ha fatto sì che venisse usato Internet come
canale di comunicazione preferenziale e come fonte primaria di reperimento
delle informazioni.
Con l’acronimo di F.A.D. si intende “Formazione a distanza”, cioè un approccio
didattico innovativo basato sui mezzi di comunicazione messi a disposizione
dalle più recenti tecnologie.
Il progenitore dell’attuale sistema d’insegnamento a distanza, usato in passato, è
rappresentato dall’insegnamento per corrispondenza attraverso al posta classica.
Tale servizio si caratterizzava per le seguenti peculiarità:
• scelta dei corsi da frequentare tramite guida ed elenco ricevuti
direttamente a casa via posta
• ricezione tramite posta ordinaria del materiale didattico presso la
propria abitazione
• possibilità conseguente di studiare e fare esercizi secondo le
disponibilità di tempo e luogo dei vari soggetti
• presenza e supporto da parte di un equipe di docenti, che, tramite
numero telefonico, rispondeva a problematiche e dubbi degli studenti in
difficoltà.
Questo sistema di apprendimento per corrispondenza metteva già in evidenza
come l’insegnamento a distanza si sviluppa secondo una modalità che prevede il
contatto, anche se non fisico, stretto e continuo tra emittente e ricevente:
caratteristica essenziale per questo tipo di approccio alla conoscenza.
Il ricevente andava a ricoprire una funzione fondamentale nell’apprendimento a
distanza in quanto il soggetto emittente poteva richiedere ad esso aiuto ogni qual
volta si trovasse di fronte una reale difficoltà.
Da questo primo rudimentale approccio di formazione a distanza, si sono evoluti
modelli di comunicazione elettronica in grado di metterci in contatto con tutto il
mondo e di superare incredibili distanze.
!
12!
1.2.2 Passaggio da Formazione a Distanza (FAD) a e-learning
La teoria della formazione a distanza (F.A.D.) si caratterizza per la distinzione
storica in tre generazioni.
La prima, nata già nell’ottocento negli USA è la scuola per corrispondenza,
aveva il fine di fornire, soprattutto agli adulti, un’istruzione di base ed una
preparazione professionale altrimenti impossibili, specialmente per i residenti in
zone isolate.
La F.A.D. di prima generazione si basava sull’invio per posta di libri, dispense e
testi. Ai corsisti era richiesto di restituire dei moduli compilati che servivano per
verificare i loro progressi.
Con la nascita del mezzo televisivo, negli anni ‘50 e ’60, queste prime
metodologie vennero affiancate dai cosiddetti sistemi di F.A.D. di “seconda
generazione”, basati sull’uso di lezioni pre-registrate su cassette audio e video e,
successivamente, software didattici, CD- ROM, e-mail ed altri supporti.
Nei sistemi di “prima” e “seconda” generazione gli obiettivi principali sono la
copertura di ampie distanze geografiche ed il raggiungimento di un gran numero
di utenti. L’apprendimento non è definito come un fatto sociale in cui
privilegiare le interazioni fra docenti e studenti quanto, piuttosto, un fatto
prevalentemente individuale.
I sistemi di “terza” generazione, invece, considerano il processo sociale l’idea
chiave dello sviluppo della formazione a distanza, in questo caso chiamata
anche on line education. In tal caso, la maggior parte del processo formativo
avviene in rete attraverso l’interazione dei partecipanti in una vera e propria
comunità di apprendimento che favorisce sia il superamento dell’isolamento del
singolo che la valorizzazione dei suoi rapporti con il gruppo. Si supera la
definizione di Formazione a Distanza per sostituirla con quella di e-learning che
denota la possibilità di apprendere assieme, anche se distanti per luogo e per
tempo, in un rapporto paritetico e di scambio non solo tra discenti, ma secondo
un modello che prevede un rapporto dinamico, policentrico, tra i diversi soggetti
della rete.
L’e-learning modifica sensibilmente i modelli erogativi dell’istruzione a
distanza classica, integrando caratteristiche fisiche della didattica a distanza e
caratteristiche psicologiche di quella in presenza o tradizionale, accentuando
nuove dimensioni con un ruolo maggiormente attivo e partecipativo assegnato ai
soggetti, un forte senso di appartenenza e presenza (comunità di apprendimento,
classi virtuali) e la possibilità di una maggiore personalizzazione del percorso di
apprendimento.
!
13!
Con l’e-learning emerge una nuova filosofia della formazione basata più sul
riutilizzo/condivisione della conoscenza già posseduta dai partecipanti e meno
sulla trasmissione dal docente al discente.
La FAD di “terza generazione” si avvale, quindi, delle reti telematiche,
sfruttando tutte le risorse dell’ICT (information e communication technology)
attualmente disponibili ed in continua evoluzione, grazie alle quali non è più
l’utente a dirigersi verso la formazione, ma è la formazione a plasmarsi in base
alle esigenze e alle conoscenze dell’utente
1.2.3 L’e-learning
Con il termine e-learning si vuole indicare l’uso della tecnologia per progettare,
distribuire, selezionare, amministrare, supportare e diffondere la formazione,
realizzando percorsi formativi personalizzati; è il nuovo modo di studiare reso
possibile dalle tecnologie dell’informazione e della comunicazione.
In un processo di e-learning l’attenzione è incentrata sull’utente. L’idea di fondo
è che la formazione dovrebbe essere intesa come un percorso al quale l’utente
partecipa attivamente; concezione del tutto diversa rispetto a quella promossa
dai precedenti sistemi di educazione a distanza, dove la formazione era vista
come un processo unidirezionale che partiva dal docente per arrivare al discente.
L’approccio metodologico adottato da un corso in modalità e-learning dovrebbe
essere capace di sfruttare tutte le specificità della rete, in particolare
l’interattività e la multimedialità. Il corsista dovrebbe essere stimolato a giocare
un ruolo attivo disponendo di materiali interattivi come strutture ipertestuali
navigabili, laboratori virtuali e materiali strutturati in un percorso formativo che
sia contestualizzato rispetto all’esperienza personale dei corsisti (life-centered),
rispetto ai compiti operativi (task - centered) e basato sulla risoluzione di
problemi (problem-centered).
L’erogazione di un’attività di e-learning può avvenire, secondo diverse
modalità:
• On-line in modalità sincrona, attraverso lo strumento della classe
virtuale in cui gli utenti interagiscono con un docente o tutor della
materia. Durante le lezioni live gli utenti possono comunicare, utilizzare
materiali in vari formati, navigare sul web sotto la guida del tutor,
scrivere su una lavagna, fare dei test, formare gruppi di lavoro guidati;
!
14!
• On-line in modalità asincrona, con una fruizione di contenuti interattivi
che favoriscono la partecipazione attiva dell’utente singolo, o della
classe virtuale, al processo di apprendimento;
• Off-line, con l’utilizzo di supporti quali testi cartacei, video, dvd o altri
materiali scaricabili e con possibilità di stampa dei contenuti in formato
testo o immagine.
Le risorse umane, intese come capacità di generare nuova conoscenza, sono
essenziali per risolvere i problemi complessi della società contemporanea ed
internet condivide e costruisce conoscenza fornendo un ambiente standardizzato
per l’e-learning.
1.2.4 Formazione in rete: principi di fondo
Dal punto di vista delle singole esperienze, le soluzioni adottabili dal punto di
vista tecnico per realizzare formazione in rete possono essere molto
differenziate per quanto riguarda: i contenuti, le modalità di fruizione, gli
strumenti utilizzati, i tempi.
Naturalmente, le scelte dipendono tanto dalle finalità e dalle caratteristiche degli
utenti quanto dalle risorse a disposizione del fornitore.
Tuttavia, i principi di fondo che ispirano la progettazione della formazione in
rete implicano la presenza di caratteristiche comuni alle diverse tipologie:
l’interattività, la modularità, la flessibilità, il ricorso a più figure professionali e
in particolare a più figure tutoriali.
L’interattività, ovvero la presenza di una forte componente comunicativa, si
realizza con la possibilità di relazionarsi in ogni momento con i docenti/tutor e
all’interno del gruppo dei pari per scambiare informazioni, esperienze e
materiali: l’esperienza formativa é basata sulla condivisione delle conoscenze e
sul confronto.
Le soluzioni tecniche per consentire l’interscambio sono plurime (ambienti di
comunicazione asincrona come forum, mailing list, e-mail o sincrona, come
chat, videoconferenze ecc.), ciascuna delle quali presenta punti di forza e aspetti
di criticità. L’interattività si realizza anche attraverso un’organizzazione e
articolazione dei contenuti che preveda la libera esplorazione ipertestuale dei
materiali offerti ed infine attraverso la possibilità di verificare il proprio
personale percorso attraverso una gamma articolata di operazioni di feed-back.
La modularità, ovvero la suddivisione dei contenuti dell’apprendimento in
“moduli didattici”.
!
15!
Per modulo didattico si intende un segmento significativo e unitario di un più
esteso percorso disciplinare o interdisciplinare in grado di far perseguire, in un
arco di tempo definito, gli obiettivi individuati. I1 modulo è a sua volta
articolato in ulteriori segmenti unitari (unità didattiche) di numero variabile.
Requisito fondamentale del “modulo” è la sua componibilità, ovvero la sua
capacità di interagire con altri moduli e di essere suscettibile di progressivi
approfondimenti.
• Nell’ambito della formazione on line, generalmente il termine
“modulo” designa non soltanto la “porzione” di curricolo con le
caratteristiche sopra definite di omogeneità, unitarietà e rispondenza a
specifici obiettivi da raggiungere in termini di conoscenza e competenza,
ma anche la forma nella quale sono articolati i diversi segmenti. Le
specifiche caratteristiche del “modulo on line” sono quindi da un lato
mutuate dalla didattica modulare, dall’altro designano anche le modalità
in cui i contenuti sono rappresentati in una struttura informatizzata.
Rispetto al modulo didattico in presenza, il modulo informatizzato presenta una
maggiore “rigidità” nel senso che deve essere compiutamente organizzato e
predisposto preventivamente.
Tuttavia, nelle soluzioni tecnologicamente più avanzate è prevista la possibilità
da parte dei docenti di intervenire in modo agile anche in corso d’opera con
integrazioni e aggiustamenti dei materiali offerti sulla base dei risultati ottenuti
dai singoli allievi.
La struttura informatizzata e le potenzialità della rete Internet aiutano a
facilitare:
• le operazioni di controllo in itinere, attraverso la possibilità di offrire una
vasta gamma di test e verifiche intermittenti (sia a risposta chiusa che aperta)
e la tracciabilità dei percorsi d’apprendimento
• la verifica e valutazione delle funzionalità del modulo attraverso l’analisi
della “memoria” del percorso didattico. L’informatizzazione consente infatti
una automatica (e perciò altamente accurata e costante) documentazione
dell’operatività di tutte le componenti del sistema
• la realizzazione da parte degli allievi di percorsi differenti, attraverso
l’ampliamento dello scaffolding di supporto (piste per l’approfondimento,
possibilità di esplorazione ipertestuale di risorse e materiali variamente
collegati al modulo.
L’utente in questo modo può muoversi liberamente all’interno di più sistemi ed
anche selezionare risorse educative da sistemi differenti. Per raggiungere questo
traguardo è stato necessario pensare a dei modelli modulari e condivisi di
rappresentazione della conoscenza e di descrizione dei contenuti che hanno
!
16!
portato all’affermazione del concetto di oggetto di apprendimento o “learning
object”.
Gli attributi essenziali di un learning object (LO) sono la modularità e la
riusabilità e si rifanno ad esigenze di efficienza ed efficacia nel processo
didattico on-line. I LO offrono una soluzione dal punto di vista sia degli utenti
sia degli sviluppatori: per gli utenti, in quanto possono offrire una modalità
adattiva per la creazione di courseware su misura in base ai bisogni e agli stili di
apprendimento propri di ciascuno; per gli autori, in quanto soddisfano le
esigenze di condivisione e riutilizzo delle risorse, di facilità di aggiornamento,
di risparmio di tempo e costi.
L’esigenza di dover avere a disposizione contenuti formativi prodotti e
riutilizzati facilmente ha fatto si che il termine “modularità” diventasse una
parola chiave dell’apprendimento in rete, intendendo con questo termine la
possibilità, per l’appunto, di riorganizzare i contenuti di un corso secondo gli
obiettivi formativi e le necessità del soggetto.
L’unità learning object più che un semplice prodotto tecnologico esprime un
modo diverso di pensare e di fruire la conoscenza secondo cui i contenuti,
svincolati dai supporti tradizionali di comunicazione, diventano fruibili
attraverso modalità fluide e immateriali che consentono una riusabilità in
situazioni e contesti molto diversi.
La flessibilità, tipici elementi di flessibilità che la F.A.D. introduce nel processo
formativo sono:
• La flessibilità di tempo: ciascuno può seguire i corsi negli orari
maggiormente
compatibili con le proprie disponibilità e secondo i ritmi individuali di
apprendimento;
• La flessibilità di spazio: ciascuno segue il corso della propria sede,
evitando spostamenti dispersivi e spesso costosi;
• La flessibilità dei materiali proposti: i materiali didattici vengono
pubblicati e
rilasciati in modalità modulare, per una fruizione agevole e
personalizzata e possono essere integrati in itinere.
Il salto di qualità, pertanto, che distingue la “terza generazione” dalle precedenti
è lo spostamento dell’attenzione dai contenuti erogati ai processi che realizzano
l’apprendimento basato su una dimensione sociale e costruttiva che vede
l’allievo protagonista attivo del proprio percorso formativo. Il concetto chiave
intorno al quale ruotano tutti gli aspetti del processo è quello dell’interazione,
definibile come possibilità che ha l’utente di influire su di un percorso didattico
!
17!
ed essere a sua volta influenzato in modo più o meno efficace e rispondente alle
proprie necessità.
1.2.5 E-learning nel panorama attuale
Al giorno d’oggi gli ambiti di applicazione dei sistemi e-learning sono
fondamentalmente tre:
• le scuole (pubbliche e private)
• le aziende
• l’amministrazione pubblica.
Nell’ ambito delle scuole spesso i progetti partono a titolo sperimentale e poi
finiscono per diventare a tutti gli effetti strumenti di supporto per diffondere
conoscenze agli studenti fuori sede o svantaggiati. Il primo corso attivato on-line
è stato creato dal politecnico di!milano e, ad oggi, sono moltissimi i laureati in
Ingegneria Informatica che hanno usufruito di tale servizio. Da Marzo 2004 poi,
in Italia è attiva la prima università completamente on-line, l’ Università
Telematica Guglielmo Marconi 4 a cui si possono iscrivere tutti coloro che
abbiano conseguito un diploma. La piattaforma e-learning della Marconi offre
una serie di strumenti per gestire la formazione interattiva in modalità sincrona
ed asincrona: lezioni in video streamng, simulatori, virtual classroom,
videoconferenza, biblioteca on-line. Basta un pc e una connessione a Internet
per entrare nel campus virtuale.
Per quel che riguarda l’ambito delle aziende, gli strumenti di e-learning vengono
utilizzati prevalentemente per scopi di formazione del personale interno. La
convenienza è notevole, non solo i dipendenti imparano più velocemente, ma
secondo un articolo apparso su "Fortune", la formazione di un dipendente che
normalmente durava dai 6 ai 9 mesi é stata ridotta a 2/3 settimane 5. Questo
aspetto unito al fatto che i dipendenti non debbano più spostarsi fisicamente a
spese dell’azienda da un posto all’altro per seguire le lezioni garantisce un
ritorno economico dell’ investimento sostenuto per acquistare la piattaforma elearning.
La Pubblica Amministrazione invece è rimasta più indietro rispetto alle aziende
per quel che riguarda l’utilizzo di queste nuove tecnologie destinate alla
formazione dei dipendenti degli enti pubblici.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
4
www.unimarconi.it
5
Tratto da un articolo della rivista “La Repubblica”
!
18!
1.2.6 Le principali necessità delle aziende italiane legate alla
formazione
Le aziende rappresentano quella categoria di fruitori della formazione che, più
di ogni altro operatore, necessitano di adeguare il loro capitale di conoscenze in
maniera repentina, per conservare il proprio livello di competitività sul mercato,
cercando di anticipare i cambiamenti più o meno prevedibili che si verificano
nell’ambiente in cui le stesse operano.
Il mondo corporate è, tradizionalmente, quello che registra una maggiore
propensione all’applicazione di soluzioni innovative al proprio interno per trarre
vantaggi competitivi da sfruttare sul mercato. Anche per ciò che concerne l’elearning, le imprese sono state pioniere nell’applicazione di questa nuova
metodologia di fare formazione, a volte a costo di produrre e/o fruire di prodotti
ancora poco collaudati e/o di scarsa qualità.
Ciò è particolarmente vero per quelle realtà aziendali di grandi dimensioni con
numerose sedi dislocate sul territorio, la cui formazione dei dipendenti su
argomenti, procedure e conoscenze strumentali all’espletamento del loro
compito risulta essere tanto più produttiva ed utile quanto più essa venga
effettuata rapidamente e simultaneamente. I benefici conseguenti al vantaggio
competitivo che deriva dall’introduzione di una nuova procedura, di un nuovo
metodo produttivo o di un nuovo modello organizzativo sono fruibili
dall’azienda tanto più rapidamente quanto più velocemente tutte le risorse
umane acquisiscono le nuove conoscenze.
A ciò si aggiunga l’esigenza delle imprese di contenere i costi legati alla
formazione e, in particolare, quelli derivati legati alle spese di trasferta dei
dipendenti, e l’esigenza di potere contare su metodologie formative che risultino
essere flessibili per ovviare alle necessità impellenti e contingenti dell’impresa.
Per le PMI, poi, è d’obbligo considerare le difficoltà legate all’assenza di ogni
singolo dipendente dal posto di lavoro anche per una sola giornata dedicata alla
formazione, perché può comportare molto spesso addirittura il “congelamento”
del processo produttivo. Allo stato attuale delle cose, questa difficoltà viene così
“aggirata” dalle PMI, che riducono al minimo gli interventi formativi, ma che
spesso si trovano in situazioni di difficoltà nel momento in cui le nuove
conoscenze tornerebbero utili.
L’e-Learning è la giusta risposta per il soddisfacimento di tutti tali bisogni, ma
ancora non ha conosciuto una diffusione ed una penetrazione consone alla sua
utilità ed alle sue potenzialità.
!
19!
2 Software PROMIS
®
PROMIS è un servizio multi lingua online che permette di ottenere una
gestione efficace ed efficiente dell’impresa fornendo soluzioni per:
•
•
•
•
Far fronte ad un complesso sistema di norme
Controllare prestazioni organizzative
Strutturare ed ordinare la documentazione in un sistema integrato di
trattamento elettronico conforme alle norme ISO e ad altri standard in
materia di ambiente, salute e sicurezza, e di qualità
Progettare e controllare il miglioramento continuo della propria attività
d’impresa.
L’obiettivo principale è quello di offrire un servizio a basso costo, alta qualità ed
ampio raggio di mercato che aiuti a strutturare ed individuare il sapere e
l’esperienza a seconda dei bisogni degli utenti supportando le organizzazioni nel
rispetto della cogenza normativa.
All’interno del software possiamo individuare 5 moduli:
1.
2.
3.
4.
5.
Il mio sapere
®
myPROMIS
Mia comunicazione
Mia qualificazione
Mio questionario
Figura'2.1'Simbolo'PROMIS.
!
20!
2.1 Visione d’insieme
®
PROMIS é la soluzione integrata per una buona ed effettiva gestione di
un’azienda. Il successo della propria attività economica dipende dalla capacità
di offrire prodotti e servizi di alta qualità, dalla cogenza con I requisiti di legge e
dalla messa in pratica delle raccomandazioni dei moderni sistemi di gestione.
Questo software è progettato per aiutare le PMI (piccolo e medie imprese) a
conformarsi alla complessità del contesto economico, giuridico e sociale in cui
esse oggi devono operare, in modo che le persone possano invece concentrarsi
sulle risorse e sulle attività aziendali. L’obiettivo principale è quello di
responsabilizzare i proprietari ed i manager a compiere i loro doveri di gestione.
Soprattutto per le piccole imprese con pochi dipendenti, mantenere l’ordine
rispettando tutti gli obblighi normativi, controllare e documentare tutte le
funzioni è un impegno oneroso in termini di tempo e questo non è facile da
realizzare. Per questo motivo prima o poi ogni impresa ha bisogno di consulenze
esterne: quanto più efficienti sono queste consulenze, tanto più efficaci i
risultati, anche in termini di costi. Da questo punto di vista PROMIS è un
sistema internet che ha già incorporato le funzionalità per soddisfare le esigenze
particolari delle imprese.
In quest’ottica PROMIS può essere utilizzato:
• Come soluzione internet per la realizzazione di un sistema di gestione
integrato singolo o multiplo.
• Come soluzione consulenziale attraverso il supporto fornito on-line dal
sistema.
• Come una soluzione intranet aziendale distribuita negli ambienti interni.
• Come strumento on-line di supporto ai consulenti che offrono servizi
speciali, metodologie o documenti.
Può inoltre essere d’aiuto per:
• Capire in che modo è possibile gestire bene la salute, la sicurezza, la qualità
ed i problemi ambientali.
• Proteggere le proprietà.
• Evitare o limitare situazioni di emergenza.
• Fare valutazioni di rischio e controllo del rischio di incendio.
• Affrontare la gestione delle crisi e dare continuità alle attività di
pianificazione.
!
21!
L’analisi dei processi di un’organizzazione, in genere è il punto iniziale per
realizzare un progetto o un’iniziativa per migliorare l’efficienza. Con PROMIS i
processi possono essere descritti, collegati con gli aspetti rilevanti dell’azienda
(equipaggiamento, personale, costi, ecc.) e documentati adeguatamente.
Spesso nelle aziende più piccole l’attenzione non è data ai processi, ma alla
gestione delle attrezzature e delle risorse, a pianificarne l’uso, a organizzarne la
documentazione, a verificarne l’aderenza a norme e regolamenti, e, in generale,
a migliorare le condizioni di sicurezza e di trasparenza di tutta l’organizzazione.
L’estrema flessibilità di PROMIS consente ai consulenti di realizzare soluzioni
adeguate alle situazioni e alle necessità dei clienti, e consente di realizzare
notevoli benefici soprattutto nella realizzazione di una base d’informazioni che
serviranno per la messa a punto di progetti successivi.
Fig 2.2: Schema di flusso per un consulente.
2.2 Metodologia
Un sistema di gestione è una struttura di processi e procedure utilizzata per
!
22!
assicurare che un’organizzazione può realizzare tutte le azioni necessarie per
raggiungere gli obiettivi richiesti.
La realizzazione di un sistema di gestione non dovrebbe essere costosa, o lunga
o complicata. Utilizzando un software adatto, molte attività possono spesso
diventare più efficienti ed economiche, anche in casi inaspettati.
I sistemi standardizzati attraverso l’Organizzazione Internazionale per gli
Standard ISO utilizzano una metodologia PDCA:
•
P (Plan)
•
D (Do)
•
C (Check)
•
A (Act)
Si tratta di un processo iterativo di quattro passi (ciclo Deming) che viene
utilizzato per gestire i processi e per risolvere i problemi. Tipicamente viene
usato per migliorare i risultati di un’azienda.
Fig 2.3: Diagramma PDCA
!
23!
Far questo significa guardare ad un’azienda o ad un’organizzazione
come ad un organismo vivo che ha processi interattivi, prodotti e servizi da
fornire. Un processo coerente con gli standard ISO è definito come: “un insieme
di attività correlate o interagenti che trasformano gli input in output”.
Figura 2.4: definizione di processo
Questi processi possono avere diverse origini, e possono essere di natura
diversa. Normalmente, è utile dividerli in tre tipi:
1. processi direttivi
2. processi produttivi
3. processi ausiliari
L'immagine che segue visualizza questo concetto, e mostra alcuni esempi per
ciascun gruppo.
Figura 2.5: diagramma dei processi aziendal
!
24!
2.3 Requisiti legali e standard
!
Se si valutano questi aspetti, che sono fondamentali per una azienda ben
organizzata in grado di adempiere ai propri doveri normativi, una cosa appare
subito evidente: la qualità, la salute e sicurezza e la protezione ambientale sono
argomenti essenziali.
Quindi non sorprende se queste applicazioni producono azioni diverse in ogni
singola organizzazione. Nel 1987, l'ISO ha pubblicato un primo schema
standard che, in quella occasione, è stato limitato alla qualità nei processi per la
produzione di prodotti e servizi. Altri sistemi di gestione, ad esempio per
l'ambiente e per la salute e la sicurezza sono stati definiti nei decenni successivi.
Tutti i sistemi di gestione hanno i lori requisiti specifici, ma sono molto simili
nella struttura. Infatti, prima bisogna:
•
•
•
•
Definire una politica, determinare gli aspetti rilevanti e gli impatti di
prodotti/servizi/attività, pianificare gli obiettivi e traguardi misurabili
(PLAN);
realizzare e applicare i programmi necessari per realizzare gli obiettivi e
raggiungere i traguardi (DO);
verificare e validare (CHECK);
applicare azioni correttive e riesaminare la gestione (ACT).
Queste procedure sono sempre le stesse, indipendentemente che la politica, gli
obiettivi ecc. siano riferiti all'ambiente, alla qualità, alla salute e sicurezza o ad
altri argomenti. Esse sono piuttosto generalizzate ed astratte. Le loro parti
devono essere interpretate attentamente perché abbiano senso.
Tutti i sistemi di gestione richiedono documentazione, registrazioni ed è
necessario anche un manuale, se si intende ottenere una certificazione. Ma si
tratta di uno sforzo minore di quello che può sembrare per far girare un sistema.
Se un'azienda registra attentamente le sue attività, la maggior parte dei requisiti
sono già disponibili.
Con un'occhiata più accurata a questi requisiti, si trova che:
•
•
•
!
i documenti esistenti devono essere controllati;
le non conformità, le azioni correttive e preventive devono essere
registrate e controllate;
gli audit interni devono essere registrati e controllati.
25!
Un'azienda o un'organizzazione possono richiedere una verifica indipendente ed
una certificazione da parte di un ente esterno autorizzato. Certificarsi rispetto ad
uno standard, tuttavia, non garantisce le prestazioni, ma certifica che
nell'organizzazione vengono applicati processi aziendali formalizzati.
Nondimeno, la pubblicizzazione che un'azienda è "certificata" o "registrata" ISO
è un possibile veicolo di mercato. E' importante valutare attentamente le ragioni
della realizzazione di un sistema di gestione. Se si deve trattare di uno strumento
di puro marketing per avere un logo appeso alla parete o per poter rispondere ad
una richiesta di un cliente, un sistema mal concepito può persino diventare
dannoso, invece di portare beneficio. Se un sistema di gestione viene introdotto
per migliorare le prestazioni, invece, il processo di miglioramento continuo può
portare a una forte competitività e ad una maggiore sicurezza a lungo termine.
2.4 Gestione della Qualità
!
Lo standard ISO 9001, il cui titolo è 'Sistemi di gestione della qualità, può
essere visto come il sistema pioniere tra tutti i sistemi standardizzati di gestione.
Per migliorare la qualità di prodotti e servizi, ISO ha pubblicato 8 principi di
qualità:
1. Orientamento al cliente 'Le organizzazioni dipendono dai clienti e quindi
devono capirne le necessità attuali e future, devono corrispondere ai loro
requisiti e sforzarsi di superare le aspettative del cliente. '
2. Direzione 'La direzione costituisce l’unità di indirizzo e di scopo
dell’organizzazione .Essa realizza e mantiene l’ambiente interno in cui il
personale può essere completamente coinvolto nel raggiungere gli obiettivi
dell’organizzazione.'
3. Coinvolgimento del personale 'Il personale, a tutti I livelli, è l’essenza di una
organizzazione ed il suo complete coinvolgimento consente di esprimere le
abilità individuali a beneficio dell’organizzazione.'
4. Approccio per processi 'Gli obiettivi possono essere raggiunti più
efficientemente quando le attività e le risorse ad esse relative sono gestite
come processo.'
5. Approccio sistemico alla gestione 'Identificare, capire e gestire processi
interrelate some un sistema unico contribuisce all’efficienza
dell’organizzazione e all’efficacia nel conseguimento degli obiettivi.'
6. Miglioramento continuo 'Il miglioramento continuo delle prestazione
dell’intera organizzazione dovrebbe essere un obiettivo permanente
dell’organizzazione.'
7. Approccio fattuale alle decisioni 'Le decisioni effettive sono basate
!
26!
sull’analisi e delle informazioni.'
8. Relazioni reciprocamente vantaggiose con i fornitori 'Un’organizzazione ed I
suoi fornitori sono interdipendenti e una relazione mutuamente vantaggiosa
migliora l’abilità di entrambi a produrre valore.
Con questi principi, si può realizzare un sistema di gestione secondo la norma
ISO 9001. La struttura ed i requisiti sono definiti in 5 parti:
•
•
•
•
•
Sistema di gestione della qualità
− Requisiti generali.
− Requisiti relativi alla documentazione.
Responsabilità della direzione
− Impegno della direzione
− Orientamento al cliente
− Politica per la qualità
− Pianificazione
− Responsabilità, autorità e comunicazione
− Riesame in direzione
Gestione delle risorse
− Messa a disposizione delle risorse
− Risorse umane
− Infrastrutture
− Ambiente di lavoro
Realizzazione del prodotto
− Pianificazione della realizzazione del prodotto
− Processi relativi al cliente
− Progettazione e sviluppo
− Approvvigionamento
− Produzione ed erogazione del servizio
− Tenuta sotto controllo delle apparecchiature di monitoraggio e di
misurazione
Misurazione, analisi e miglioramento
− Generalità
− Monitoraggio e misurazione
− Tenuta sotto controllo del prodotto non conforme
− Analisi dei dati
− Miglioramento
Recentemente, è stata pubblicata la quarta revisione di questo standard e molti
!
27!
utenti hanno atteso per aggiornare il loro sistema di gestione della qualità dalla
ISO 9001:2000 alla ISO 9001:2008. L’ultima versione non introduce nuovi
requisiti importanti, ma contiene alcuni chiarimenti e alcune modifiche orientate
a migliorare la consistenza verso i sistemi con lo standard ambientale ISO
14001:2004.
ISO fornisce online aiuto e documentazione di guida per lo standard ISO 9001.
2.5 Gestione ambientale
!
Per la gestione dell'ambiente esiste lo standard internazionale ISO 14001. La
prima versione di questo standard è stata pubblicata nel 1996 come ISO
14001:1996 e aggiornata nel 2004 come ISO 14001:2004. Lo standard specifica
i requisiti per:
•
•
•
stabilire una politica ambientale;
determinare gli aspetti e gli impatti ambientali di prodotti/attività/servizi;
pianificare obiettivi e traguardi ambientali misurabili, e segue i passi
consueti del ciclo Plan, Do, Check and Act nel contesto della gestione
ambientale.
In questo modo, un'azienda che realizza miglioramenti tecnici ed organizzativi
può, ad esempio, risparmiare materie prime e ridurre il consumo di energia,
oppure ridurre i reflui idrici o i gas esausti.
ISO fornisce online aiuto e documentazione di guida per lo standard ISO 14001.
EMAS è l'abbreviazione di Eco Management and Audit Scheme. Questo schema
combina la gestione e l'audit dell'ambiente per le organizzazioni che vogliono
migliorare le loro prestazioni sotto il profilo ambientale ed è stato sviluppato
dall'Unione Europea come "Nuovo strumento per le politiche ambientali". Le
organizzazioni che partecipano all'EMAS devono pubblicare una dichiarazione
ambientale nella quale riportano il loro impatto (diretto o indiretto)
sull'ambiente, le loro prestazioni ambientali ed i loro obiettivi ambientali.
L'Unione Europea mantiene un portale web per incoraggiare le imprese a
partecipare ed un'area in particolare per le piccole e medie imprese è stata
realizzata qui.
!
28!
2.6 Salute sul lavoro e gestione della sicurezza
!
Benché la salute e la sicurezza siano considerati cruciali per tutte le
organizzazioni, non esiste ancora uno standard internazionale per la gestione del
sistema OSH allo stesso livello degli standard come ISO 9001 o ISO 14001.
Alla fine degli anni '90 si è discusso se definire uno standard ISO per la salute e
la sicurezza, ma senza raggiungere un accordo. Sono stati fatti altri sforzi, in
seguito, attraverso l'Organizzazione Internazionale del Lavoro (ILO) per
definire una linea guida non vincolante per iniziative nazionali o altre ancora.
Recentemente, è stata pubblicata la quarta revisione di questo standard e molti
utenti hanno atteso per aggiornare il loro sistema di gestione della qualità dalla
ISO 9001:2000 alla ISO 9001:2008. L’ultima versione non introduce nuovi
requisiti importanti, ma contiene alcuni chiarimenti e alcune modifiche orientate
a migliorare la consistenza verso i sistemi con lo standard ambientale ISO
14001:2004.
Un gruppo di lavoro guidato dal British Standards Institution (BSI) ha
sviluppato una specifica per i sistemi di gestione di salute e la sicurezza
(OHSAS 18001 - Occupational Health and Safety Assessment Series). La
specifica, in sé, non è uno standard riconosciuto, ma è basato sul British
Standard BS9900:1996 e può servire come guida per applicare un sistema di
gestione OSH; è anche possibile ottenere una certificazione secondo il sistema
OHSAS, ma è opzionale ed è applicabile solo su base volontaria. La struttura
del sistema OHSAS è molto vicina a quella dello standard ISO 14001.
La versione corrente di questa specifica è la OHSAS 18001:2007, che contiene
alcune modifiche di minor conto rispetto alla prima versione del 1999, in modo
da garantire una migliore coerenza con lo standard ISO 14001:2004.
Le leggi nazionali su salute e sicurezza prevedono normalmente che
un'organizzazione deve:
•
•
•
•
•
!
avere una politica scritta relativa alla salute e sicurezza (nel Regno Unito
si riferisce ad aziende con 5 o più dipendenti);
verificare tutti i rischi (OHS) che possono riferirsi ai dipendenti o
qualsiasi altra persona;
adoperarsi per la pianificazione effettiva, il controllo, il monitoraggio ed
il riesame di misure OSH preventive e protettive;
assicurarsi che tutti i dipendenti abbiano un sistema competente per il
controllo della salute e sicurezza;
consultare i dipendenti in riferimento ai loro rischi sul lavoro e applicare
29!
correntemente misure preventive e protettive.
Il ciclo PDCA è presente anche in altri approcci simili. Il sistema Health and
Safety Executive (HSE) del Regno Unito, per esempio, preferisce presentarlo in
modo più specifico per la salute e sicurezza:
1.
plan (pianifica)
2.
deliver (consegna)
3.
monitor (sorveglia)
4.
review (riesamina)
Relativamente alla gestione della salute e sicurezza, vi sono altri buoni sistemi
oltre ad OHSAS 18001. In funzione del settore di attività o della nazione, vi
sono sistemi come:
•
•
2.7
SCC - 'Safety Certificate Contractors', che è un sistema combinato di
gestione per salute, sicurezza e ambiente sviluppato nell'industria
petrolchimica;
OHRIS - Occupational Health- and Risk Management System,
sviluppato dalle Autorità bavaresi (disponibile solo in tedesco).
L’approccio integrato
Un sistema di gestione integrata (Integrated Management System, IMS)
combina metodi e strumenti per applicare i requisiti richiesti da diverse aree
entro una struttura organizzata singola. Utilizzando sinergie e fonti di risorse si
può ottenere un sistema più efficace e fattibile di quanto non possa esserlo uno
frammentato.
La possibilità migliore, per un IMS, è probabilmente quella di partire da zero, in
modo da poter ottimizzare la struttura. In molti casi, tuttavia, ci si trova di fronte
ad un sistema di gestione già funzionante - molto spesso un sistema di gestione
della qualità - mentre gli altri sistemi, come l'ambiente e la salute e sicurezza,
vengono integrati successivamente.
Al momento, non esiste uno standard formale, né europeo, né internazionale, in
grado di fornire una guida per realizzare un IMS, anche se questo non significa
!
30!
che non vi sia un servizio di supporto qualificato. Le autorità locali, gli enti
nazionali, le università hanno pubblicato eccellenti documenti per introdurre e
applicare questi sistemi, ma, come anticipato, non si tratta di standard.
®
PROMIS è stato progettato per fornire il supporto a sistemi completamente
integrati e si basa sui requisiti ISO9001 (qualità), ISO14001 (ambiente),
OHSAS 18001 (salute e sicurezza) e ISO17025 (controlli e misure). I formati di
gestione sono integrati e trasversali attraverso tutti questi standard, in modo che
le competenze gestionali e la gestione dei documenti sia univoca in modo
efficace ed effettivo, e questo semplifica moltissimo le operazioni di una
organizzazione. Questa semplice struttura integrata è così potente che può far
fronte a qualsiasi standard di gestione o normativa gestionale, come ad esempio
i requisiti di sicurezza per l'Information Technolgy definiti dalla ISO 27001.
L’obiettivo di questa sezione è quello di definire una tassonomia integrata del
Modello di Struttura dell’Albero degli Oggetti in modo che vi sia una posizione
logicamente definita per qualsiasi cosa in grado di abilitare qualsiasi altra cosa,
quindi la realizzazione di un ordine.
Il Modello di Struttura dell’Albero degli Oggetti fornisce una classificazione
(tassonomia) gerarchica integrate degli aspetti che qualsiasi generica
®
organizzazione potrebbe dover gestire. Qualsiasi utente di myPROMIS può
usare la struttura completamente o parzialmente, secondo necessità. Questa
struttura integrata permette di evitare il ricorso a sotto-strutture frammentate
orientate alla gestione commerciale, alla gestione della qualità, alla salute e
sicurezza, alla gestione dell’ambiente, alla gestione della sicurezza ecc.
La struttura è presentata su due gerarchie tassonomiche che comprendono:: (A)
– ‘Struttura’ e (B) - ‘Dinamiche’.
Strutture e dinamiche sono sempre presenti e riconoscibili in qualsiasi
organizzazione:
•
•
•
•
con dimensioni grandi, medie, piccole o piccolissime;
che forniscono servizi o prodotti;
che sono progettualizzate e non progettualizzate;
che sono private o pubbliche.
La classificazione degli argomenti e delle azioni della gestione in base a
strutture gerarchiche è importante per realizzare ambienti di lavoro in grado di
assistere tutti coloro che lavorano nell'organizzazione, in modo da aiutarli a
essere maggiormente produttivi, creativi e soggetti ad uno stress minore. Tutto
!
31!
questo consente di raggiungere un più alto livello organizzativo, che è quindi in
grado di aderire a tutti gli standard normativi e legislativi.
!
32!
3 Metodologia FMECA
3.1 Introduzione
La FMECA (Failure Modes, Effects and Criticality Analisys) è una metodologia
di studio affidabilistico pensata originariamente a supporto della progettazione
di sistemi complessi. Più recentemente ha trovato ampio spazio di applicazione
in altri ambiti di utilizzo come l’analisi di processo e la manutenzione
industriale.
Sostanzialmente la metodologia FMECA è costituita da una procedura per
l’analisi di un’entità complessa (macchina, impianto, sistema di qualsiasivoglia
natura) fondata su 2 principi fondamentali:
• Scomposizione gerarchica dell’entità sotto esame in sottogruppi a
complessità decrescente, fino ad arrivare al livello di dettaglio desiderato. Si
ottiene così uno schema ad albero rovesciato.
• Esecuzione dell’analisi di affidabilità ad ogni livello e cioè determinazione
di modo, causa, meccanismo ed effetto del guasto a quel livello, valutando
in modo opportuno la criticità dell’entità in esame.
Alla fine di questo processo di analisi si ottiene un quadro estremamente
articolato e documentato del modo e della probabilità con cui si possono
generare i guasti nell’entità e si possono quindi definire le più opportune azioni
di progettazione, pianificazione e miglioramento della manutenzione.
3.2 FMECA e FMEA
Inizialmente la FMECA nasce con il nome di FMEA (Failure, Mode and Effect
analysis), ovvero non era prevista la fase di analisi di rischio che veniva lasciata
alla discrezione del fruitore della FMEA.
La FMEA è un’analisi di tipo qualitativo intesa a definire quello che potrebbe
succedere (il modo di guasto/errore) se si verificasse un difetto, una omissione,
un errore.
La FMECA aggiunge un percorso di tipo quantitativo orientato all’assunzione di
decisioni operative coerenti.
!
33!
Nella pratica attuale i due termini si equivalgono, in particolare ormai quando si
parla di FMEA si intende FMECA e la parte di analisi di rischio può essere
trattata in svariati modi, in base allo standard utilizzato.
3.3 Terminologia
E’ utile, prima di presentare la metodologia, richiamare la terminologia
usualmente adottata nel corso dello studio FMECA.
• Modo di guasto: modo in cui si manifesta il guasto e il suo impatto sulle
operazioni di un’entità (totale, parziale, intermittente).
• Meccanismo di guasto: fenomeno naturale di degrado del funzionamento di
un’entità che, perdurando nel tempo, può portare al guasto della stessa (può
essere: processo fisico di carico meccanico, processo fisico di carico
termico o processo chimico/fisico di invecchiamento)
• Causa di guasto: origine determinante che spiega il guasto, cioè la
circostanza che porta al guasto, di un’entità (il guasto può essere dovuto a:
non adeguata progettazione, non adeguata fabbricazione, non adeguata
installazione, usura, utilizzazione scorretta, uso improprio, errata
manutenzione)
• Effetto di guasto: conseguenze che un modo di guasto ha sulla funzionalità
dell’entità.
• Effetto locale: conseguenze che un modo di guasto ha sulla funzionalità di
un’entità al livello di scomposizione più basso (livello dell’item
componente l’entità).
• Effetto superiore: conseguenze che un modo di guasto ha sulla funzionalità
di un’entità al livello di scomposizione immediatamente superiore a quello
in cui è stato individuato l’effetto locale (livello dell’assieme di cui l’item
componente dell’entità è parte)
• Effetto finale: conseguenze che un modo di guasto ha sulla funzionalità di
un’entità al livello di scomposizione più alto (livello dell’entità vista come
sistema completo).
!
34!
• Azione correttiva: modifica documentata del progetto,del processo, di una
procedura, dei materiali utilizzati, implementata per correggere un difetto
progettuale e/o prevenire o limitare una causa di guasto.
3.4 Metodologia
3.4.1 Scomposizione dell’entità.
Per guidare la scomposizione sono disponibili due criteri:
• Scomposizione guidata dal rischio associato al guasto/guasti:
In accordo a tale criterio, si procede alla scomposizione di quelle entità che
risultano critiche per la severità degli effetti di guasto (durata del guasto
molto elevata, forte riduzione di capacità produttiva disponibile, danno
ambientale, ecc.) e/o per le probabilità di accadimento del guasto (frequenza
elevata di guasto).
L’analisi statistica dello storico evidenzia facilmente la necessità, per
esempio, di scomporre ulteriormente alcuni dei gruppi funzionali.
• Scomposizione guidata dai compiti di supporto logistico della manutenzione:
Questo secondo criterio basa la scomposizione degli oggetti di manutenzione
in funzione dei compiti di supporto logistico che sono affidati alla
manutenzione. In accordo a questo criterio, la scomposizione viene attuata in
base ai compiti da assegnare alla responsabilità della funzione manutenzione
fino al livello dei componenti rimpiazzati e/o tenuti sotto controllo (oggetti
sotto controllo con monitoraggio continuo o ispezione a cadenza).
!
35!
Metodologia1FMECA
Fasi
Descrizione
Scomposizione+dell'entità
Scomposizione+dell'entità+nei+suoi+sottoinsiemi+principali+(gruppi+
funzionali,+assiemi+e+sottassiemi)+e+item+componenti
Individuazione+dei+modi,+dei+meccanismi+e+
delle+cause+di+guasto
Individuazione+dei+modi+di+guasto,+dei+meccanismi+e+delle+cause+
potenzialmente+associati+all'entità+(ai+suoi+sottosistemi+e+agli+item+
componenti)
Individuazione+degli+effetti+di+guasto
Individuazione+degli+effetti+di+guasto+associati+a+ciascun+modo+di+
guasto
Individuazione+dei+sintomi+e+dei+metodi+di+
rilevazione
Individuazione+dei+sintomi+di+guasto+incipiente/avvenuto+associati+a+
ciascun+modo+di+guasto+e+dei+metodi+e+delle+modalità+di+rilevazione+
precoce/successiva+al+guasto
Analisi+delle+criticità
Attribuzione+dell'indice+di+criticità(detto+anche+indice+di+rischio)+
associato+a+ciascun+modo+di+guasto
Individuazione+delle+azioni+correttive+e+
pianificazione+della+manutenzione
Individuazione+degli+interventi+di+manutenzione+preventiva+richiesti;+
individuazione+delle+proposte+di+manutenzione+migliorativa;+
individuazione+dei+requisiti+di+supporto+logistico+(specializzazioni+di+
mestiere+e+squadre+di+manutenzione,+parti+di+ricambio,+materiali+di+
consumo,+attrezzature+di+supporto)
Figura 3.1. Fasi della metodologia FMECA per progettazione del piano di manutenzione.
3.4.2 Livelli di scomposizione di un’entità
Si può quindi scomporre un’entità in vari livelli:
• Primo livello: corrisponde all’entità in esame (macchina, stazione operativa)
• Secondo livello: si individuano i sottosistemi/gruppi funzionali dell’entità.
• Terzo livello: si individuano i sotto-assiemi preposti alle operazioni
elementari necessarie alla operatività dei sottosistemi/gruppi funzionali
dell’entità.
• Quarto livello: si individuano gli item componenti (elettrici, elettronici,
idraulici, meccanici, …) di ciascun sotto assieme soggetti al guasto.
!
36!
Macchina'utensile'
Gruppo'
mandrino'
Motore'
mandrino'
Spazzole'
Sistema'
bloccaggio'
utensile'
Cuscine;'
Sistema'
tavola'porta'
pezzo'
Sistema'
controllo'
assi'
….'
….'
….'
Figura 3.2. Esempio di scomposizione di una macchina utensile a controllo numerico
Il meccanismo di scomposizione è utile per focalizzare l’attenzione sui
meccanismi e le cause di guasto (la scomposizione porta l’analista a
concentrarsi sulle parti dell’entità dove si origina il meccanismo/causa del
guasto), aiuta inoltre a definire con precisione gli effetti di guasto (la
scomposizione porta l’analista a discriminare se l’effetto di guasto interessi il
livello componente, il livello sotto-assieme superiore o l’entità completa).
3.4.3 Selezione delle entità critiche
Ad ogni livello di scomposizione è bene effettuare un’analisi di quali siano a
quel livello le entità critiche in modo da guidare il successivo livello di
scomposizione (un’entità riconosciuta come non critica potrà non essere
ulteriormente scomposta senza perdere accuratezza nell’analisi).
La selezione delle entità critiche serve ad identificare per quali entità del sistema
i guasti sono da ritenersi critici per la sicurezza e/o la capacità di
produzione/servizio del sistema medesimo.
!
37!
Selezione.entità.critica
Fasi
Descrizione
Analisi'ABC'di'Pareto
Selezione'basata'su'indicatori'di'prestazione'(ad'es.'MTBF,'MDT,'
indicatori'di'costo'manutenzione)'derivati'da'un'analisi'dello'storico'
guasti'delle'entità'installate'nell'impianto.
Reliability'block'diagram'(RBD)
Selezione'basata'sull'analisi'del'contributo'dell'entità'all'affidabilità'
del'sistema
Functional'failure'Analisys'(analisi'dei'guasti'
funzionali)
Selezione'basata'su'un'indice'di'rischio'derivato'dalla'probabilitàdi'
accadimento'e'dalla'severità'degli'effetti'dei'guasti'delle'diverse'
entità'sul'sistema.
Figura 3.3. Metodi di selezione dell’entità critica in un sistema produttivo.
3.4.4 Individuazione dei modi, dei meccanismi e delle cause di
guasto.
• Individuazione modi di guasto
Obiettivo di questa fase dello studio FMEECA è, prima di tutto, individuare i
modi di guasto dell’entità. A tal fine, è prassi, dapprima, la stesura di un
elenco di funzioni eseguite dell’entità. Saranno, poi, individuati i modi di
guasto di ciascuna funzione, unitamente alle parti dell’entità (sotto assiemi e
componenti) dove i guasti si originano. E’ chiaramente pregiudiziale, allo
svolgimento di questa fase, l’aver provveduto alla scomposizione dell’entità.
È opportuno osservare che il modo di guasto trova spesso, nella pratica
industriale, le descrizioni più variegate. Qui si è preferito utilizzare una
descrizione che distingue il modo di guasto in 3 tipi in relazione all’avaria
che ne consegue: totale, parziale, intermittente.
Esistono inoltre almeno altri 2 approcci nella pratica industriale: il primo
approccio classifica il modo di guasto considerando il ‘suo impatto
sull’operatività dell’entità’, o, ciò che è equivalente, sull’abilità di eseguire
una o più delle funzioni richieste per assicurare l’operatività.
Il secondo approccio corrisponde a descrivere il modo di guasto per ‘il modo
in cui si manifesta’ fisicamente.
• Individuazione dei meccanismi e delle cause di guasto
Dall’individuazione dei modi di guasto dell’entità si passa all’individuazione
del meccanismo e della causa che li hanno determinati (meccanismi e cause
se più di uno): vengono, in particolare, identificati per ogni modo di guasto
dell’entità, i meccanismi e le cause più probabili.
L’identificazione di meccanismi e cause di guasto è essenziale per una buona
progettazione del piano di manutenzione: per sua definizione, il piano nasce,
infatti, per eliminare o , tutt’al più, limitare meccanismi e cause di guasto; al
!
38!
contrario, con una descrizione ambigua di meccanismi e cause, la proposta
degli interventi di manutenzione da prevedere nel piano può essere
irrimediabilmente fuorviata.
3.4.5 Individuazione degli effetti del guasto
Per ciascun modo di guasto, gli effetti (distinti tra effetti locali, superiori efinali)
possono essere di diversa natura:
! Mancata sicurezza (sull’ambiente e sulle persone);
! Mancata erogazione del servizio (mancato utilizzo della capacità
produttiva/servizio);
! Mancata qualità (scarto, rilavorazioni, resi di prodotti difettosi, ….);
! Inefficienza di esercizio (extraconsumi di utilities e materiali);
! Impegno di materiali di manutenzione (quantità di materiale sostituito o
riparato);
! Impegno di personale di manutenzione (ore di manodopera impiegata
negli interventi).
L’effetto può essere valorizzato attraverso il suo costo proprio o indotto di
manutenzione.
3.4.6 Individuazione dei sintomi di guasto e dei metodi di
rilevazione
Per ciascun modo di guasto, e le relative cause, si possono individuare i sintomi
premonitori e i sintomi a guasto avvenuto, utili, rispettivamente, come segnali
per la diagnosi prima del guasto o a seguito del suo accadimento.
L’individuazione dei sintomi di guasto è un primo passo per poter valutare se è
possibile pianificare una manutenzione su condizione/predittiva.
Il secondo passo consiste nell’individuazione dei metodi di rilevazione del
sintomo di guasto.
A titolo d’esempio si propone la seguente tabella che presenta una serie di
possibili sintomi a cui corrispondono i relativi metodi di rilevazione.
!
39!
Sintomi*e*metodi*di*rilevazione
Sintomi
Metodi*di*rilevazione
Perdite'd'olio,'rumore,surriscaldamento,…
Ispezioni'sensoriali'(non'strumentate)
Variazione'di'spessori,'variazioni'di'
eccentricità,…
Ispezioni'strumentate'(con'strumenti'non'specialistici'
ad'es.'un'calibro)
Distribuzione'delle'temperature,'frequenza'e' Monitoraggio'diagnostico'(con'strumenti'specialistici'
valore'assolutodelle'vibrazioni,…
ad'es.'termocamera)
Velocità'di'rotazione'di'un'motore,'portata'
erogata'di'fluido'di'processo,…
Controllo'di'processo'(con'sensori'di'controllo'di'
processo)
Difetti'di'saldatura
Test'specialistici'sui'materiali'(con'strumenti'di'test'
specialistici'ad'es.'Raggi'X)
Fig. 3.4. Metodi di rilevazione guasti
3.4.7 Analisi delle criticità
L’analisi delle criticità è una delle fasi più importanti della metodologia
FMECA, ha lo scopo di valorizzare il rischio operativo associato a ciascun
modo di guasto. La valorizzazione è basata sull’assegnazione di un cosiddetto
indice di criticità (o indice di rischio). L’indice può essere calcolato con diverse
modalità. Nella versione proposta da fonti in ambito SAE (mettere nota) l’indice
di criticità è denominato, in inglese, Risk Priority Number ed è calcolato come il
prodotto di tre fattori:
!"#! !"#$!!"#$"#%&!!"#$%& = !O ∗ S ∗ D
Dove:
− O è il fattore che misura l’occurrence, cioè la probabilità di accadimento
stimata per il guasto;
− S è il fattore che misura la Severity, cioè la severità (o gravità) degli effetti
del guasto;
− D è il fattore che misura la Detectability, cioè la facilità con cui il guasto può
essere rilevato in anticipo mediante rilevazione del sintomo premonitore e/o
la facilitàcon cui è rilevato a guasto avvenuto.
!
40!
Ciascun fattore è definito a partire da una propria scala a punteggio. La scala è
costruita assegnando dei punteggi crescenti in corrispondenza del
peggioramento delle condizioni di rischio associate: più in alto è il punteggio,
peggiore è la Occurrence (è più probabile che capiti il guasto), la Severity
(l’effetto di guasto è più grave/severo), la Detectability (è meno facile rilevare in
anticipo il guasto incipiente e/o diagnosticare il guasto avvenuto).
Le scale sono definite con un approccio che si potrebbe definire semiquantitativo. Se possibile, la scala è costruita facendo corrispondere il punteggio
ad un range di un indice quantitativo e rappresentativo del rischio crescente. Ad
es. il MDT (Mean Down Time) è un indice che può essere ben utilizzato per la
misura quantitativa della Severity di un effetto di guasto di mancata erogazione
del servizio; il fattore Severity assume quindi un punteggio più elevato per
guasti caratterizzati da un range di MDT maggiore.
In altri casi il punteggio dell’RPN è l’espressione sintetica di una descrizione
qualitativa. È tipicamente il caso della Detectability, definita, in genere,
attraverso una valutazione generale (e quindi una descrizione), che può
combinare elementi diversi:
• Riscontro dell’esistenza di un chiaro sintomo premonitore di guasto (ci si
chiede se il sintomo esiste o non esiste).
• Esistenza della base tecnica o strumentale per rilevare il sintomo (ci si
chiede se esiste o no la possibilità tecnica di rilevare il sintomo, anche in
maniera strumentale).
• Capacità di organizzare campagne di rilievo (ci si chiede se esistono
competenze interne o di terzi disponibili per le campagne di rilievo).
Sono riportate di seguito, a titolo esemplificativo, le possibili scale dei tre fattori
Occurrence, Severity, Detectability per una FMECA così come definite in
ambito SAE.
L’Occurrence è definita attraverso un criterio quantitativo, partendo cioè dal
confronto tra l’indice MTBF e il tempo T richiesto dall’utente senza che
accadano guasti. Più alto è il MTBF rispetto al tempo T, minore è la probabilità
di accadimento di guasto, minore è il punteggio assegnato all’Occurrence.
!
41!
Occurrences(as(Reliability(based(on(the(user's(required(time
MTBF%about%10%%of%the%user's%required%time
MTBF%about%30%%%of%the%user's%required%time
MTBF%about%60%%of%the%user's%required%time
MTBF%equal%to%the%user's%required%time
MTBF%2%times%greater%than%the%user's%required%time
MTBF%4%times%greater%than%the%user's%required%time
MTBF%6%times%greater%than%the%user's%required%time
MTBF%10%times%greater%than%the%user's%required%time
MTBF%20%times%greater%than%the%user's%required%time
MTBF%50%times%greater%than%the%user's%required%time
Fig 3.5.Occurrence O basata sul MTBF.
Ranking
10
9
8
7
6
5
4
3
2
1
L’Occurrence è anche definibile in funzione del valore dell’affidabilità R(T) al
tempo T. Nella seguente tabella si assume l’ipotesi che il macchinario sia in vita
utile, quindi con funzione di densità di probabilità di guasto esponenziale. La
tabella 4.3.7.(2) è del tutto equivalente alla precedente 4.3.7.(1), infatti con
l’assunta ipotesi di legge di affidabilità esponenziale , dire che il MTBF è uguale
al tempo T richiesto dall’utente è equivalente a dire che l’affidabilità
R(T=MTBF) è pari a circa il 37% .
Che sia una o l’altra scala il punteggio assegnato all’Occurrence è quindi il
medesimo.
Occurrences(as(Reliability(based(on(the(user's(required(time
R(T)<1%
R(T)<5%
R(T)<20%
R(T)<37%
R(T)<60%
R(T)<78%
R(T)<85%
R(T)<90%
R(T)<95%
R(T)<98%
Fig 3.6. Occurrence O basata sull’affidabilità.
Ranking
10
9
8
7
6
5
4
3
2
1
Un’ulteriore scala è infine basata sulla misura del numero di guasti registrati per
ore di funzionamento: maggiore è il numero di ore di funzionamento per
l’accadimento di un guasto, minore è la probabilità di accadimento del guasto,
minore è , quindi, il punteggio assegnato all’Occurrence.
!
42!
Occurrences(as(Possible(number(of(Failures(within(Hours(of(
Operation
Ranking
1"in"1
1"in"8
1"in"24
1"in"80
1"in"350
1"in"1000
1"in"2500
1"in"5000
1"in"10000
1"in"25000
Fig 3.7. Occurrence O basata sula frequenza dei guasti.
10
9
8
7
6
5
4
3
2
1
La scala di Severity, di seguito riportata, misura invece la gravità degli effetti di
guasto di diversa natura: nell’ordine di criticità decrescente, effetti di mancata
sicurezza, mancata produzione e mancata qualità, tempo impiegato per
effettuare regolazioni e altri controlli di processo.
Effects
Severity,of,effects
Ranking
Affects)operator,)plant)or)maintenance)personnel,)safety)and/or)affects)non)
Hazardous)(without)warning)
compliance)with)government)regulations,)without)warning
10
Hazardous)(with)warning)
Affects)operator,)plant)or)maintenance)personnel,)safety)and/or)affects)non)
compliance)with)government)regulations,)with)warning
9
Very)high
Downtime)more)than)8)hours)or)the)production)of)defective)parts)for)more)
than)4)hours
8
High
Downtime)between)4)and)8)hours)or)the)production)of)defective)parts)for)
more)than)4)hours
7
Moderate
Downtime)between)1)and)4)hours)or)the)production)of)defective)parts)
between)1)and)2)hours
6
Low
Downtime)between)30)minutes)and)1)hour)or)the)production)of)defective)
parts)up)to)1)hour
5
Very)low
Downtime)between)10)and)30)minutes)but)no)production)of)defective)parts
4
Minor
Downtime)up)to)10)minutes)but)no)production)of)defective)parts
3
Very)minor
Process)parmeter)variability)not)within)specification)limits.)Adjustments)or)
other)process)controls)need)to)be)taken)during)production.)No)downtime)
and)no)production)of)defective)parts.
2
None
Process)parameter)variability)within)specification)limits.)Adjustments)or)
other)process)controls)can)be)done)during)normal)maintenance.
1
Fig 3.8. Scala Severity S (fonte SAE)
!
43!
Effects
Almost'impossible
Very'remote
Remote
Very'Low
Low
Moderate
Moderately'high
High
Very'High
Almost'certain
Severity,of,effects
Design'or'machinery'controls'cannot'detect'a'potential'cause'and'
subsequent'failure'or'there'are'no'design'or'machinery'controls.
Very'remote'chance'that'design'or'machinery'controls'will'detct'a'potential'
cause'and'subsequent'failure'mode.
remote'change'that'design'or'machinery'controls'will'detect'a'potential'
cause'and'subsequent'failure'mode.'Machinery'control'will'provide'
indication'of'failure.
Design'or'machinery'controls'do'not'prevent'the'failure'from'occurring.'
Machinery'control'will'isolate'the'cause'and'subsequent'failure'after'the'
failure'has'occurred.
low'change'that'design'or'machinery'controls'will'detect'a'potential'cause'
and'subsequent'failure'mode.'Machinery'control'will'provide'an'indicator'
of'imminent'failure.
medium'change'design'controls'will'detect'a'potential'cause'and'
subsequent'failure'mode.'Machinery'control'will'prevent'imminent'failure.
moderately'high'chance'design'controls'will'detect'a'potential'cause'and'
subsequent'failure'mode.'Machinery'control'will'prevent'imminetn'failure.
High'chance'that'design'controls'will'detect'a'potential'cause'and'
subsequent'failure'mode.'Machinery'control'will'prevent'imminent'failure'
and'isolate'the'cause.
very'high'chance'that'design'controls'will'detect'a'potential'cause'and'
subsequent'failure'mode.'Machinery'controls'may'not'be'required.
Design'controls'almost'certain'to'detect'a'potential'cause'and'subsequent'
failure'mode.'Machinery'controls'not'required.
Ranking
10
9
8
7
6
5
4
3
2
1
Fig 3.9. Scala di Detectability D (Fonte SAE)
Osservazioni:
• Per quanto riguarda l’Occurrence, la sua valutazione presuppone la
disponibilità di uno storico dei guasti (da cui dedurre MTBF, numero degli
interventi a guasto o R(T)). In caso di mancanza di storico, la stima è
comunque fatta da esperienza su macchine simili e/o a partire da altre fonti
(manuali del costruttore).
• La Severity è, invece, una scala che dipende in maniera rilevante dalla natura
delle entità in studio: in particolare, dai loro effetti tipici di guasto(es.
mancanza di sicurezza, qualità, …) e dalle modalità di gestione della
manutenzione.
• La Detectability è un fattore che dipende fortemente dall’esistenza di sintomi
premonitori del guasto incipiente e/o sintomi di guasto avvenuto e
dall’implementazione dei relativi metodi di rilevazione. In alcuni casi non è
per niente migliorabile perché non esistono sintomi di guasto.
• In alcuni casi è possibile che le tre scale di punteggio possano richiedere una
progettazione specifica.
• È utile cercare id mantenere uno standard che va al di là del singolo contesto
aziendale. È il caso in cui il gestore dell’impianto può richiedere al
costruttore della macchina, se è il caso, la documentazione FMECA di
!
44!
progetto. In questo scenario, è evidente che è necessaria la condivisione di
uno standard che sia valido al di la delle mura della singola azienda.
3.4.8 Individuazione delle azioni correttive
Una volta che, a valle dell’analisi di criticità, sono stati selezionati modi di
guasto e componenti critici, si passa alla fase propositiva dello studio FMECA.
Vengono quindi, in questa fase, individuate azioni correttive con lo scopo di
correggere, prevenire o limitare una causa di guasto.
Le azioni correttive sono, in genere, di diversa natura e possono comprendere:
modifiche di progetto, del processo, di una procedura, dei materiali utilizzati.
Si possono individuare le principali azioni correttive che sono sotto la
responsabilità della manutenzione:
• Provvedimenti a carattere non periodico di manutenzione migliorativa
(Piccole modifiche di progetto di impianto).
• Revisioni periodiche al piano di manutenzione corrente, con le relative
modifiche a procedure ed interventi di manutenzione preventiva previsti
a piano.
• Modifiche a procedure di gestione dei ricambi di manutenzione (es.
modifica delle politiche di gestione delle scorte).
• Provvedimenti che prevedono modifiche rilevanti al progetto o rimessa a
nuovo dell’impianto in alcune sue parti ed eventuali ammodernamenti
tecnologici e modifiche di processo.
3.4.9 Pianificazione della manutenzione
Il risultato finale per uno studio FMECA è il piano di manutenzione. Partendo
dall’individuazione dei componenti e modi di guasto critici si può sviluppare il
piano attraverso la raccolta di tutte le proposte di interventi di manutenzione
preventiva (es. ispezioni, sostituzioni preventive cicliche, pulizie, lubrificazioni,
…) utili ad abbattere le criticità.
Le informazioni più comunemente utilizzate, per caratterizzare le specifiche
d’intervento, sono:
− Codice operazione
− Descrizione intervento
− Frequenza o periodo di intervento
− Tipo di lavoro
!
45!
−
−
−
−
Tempo dell’intervento
Tipo di personale richiesto
Numero di persone impiegate
Materiali
Il totale delle informazioni raccolte definisce lo standard del lavoro di
intervento. Solitamente si riferisce lo standard del lavoro di intervento
all’oggetto di manutenzione di terzo livello, cioè ad un sotto assieme di
macchina. Al sotto assieme vengono quindi assegnati tutti gli interventi di
manutenzione ritenuti necessari ad eliminare o limitare le cause di guasto
individuate al quarto livello della scomposizione, quello degli item componenti
dove il guasto si genera.
3.5 FMECA: benefici e punti deboli
L’analisi FMEA è un potente strumento di qualità che permette, attraverso un
meccanismo di miglioramento continuo del processo, di assecondare i bisogni e
i requisiti del mercato.
Come tutti gli strumenti di qualità essa presenta dei vantaggi e allo stesso tempo
dei limiti insiti nella natura stessa della metodologia.
I principali benefici sono:
•
•
•
•
•
•
•
•
•
•
•
!
Offre la certezza che tutte le possibilità di guasto concepibili siano state
identificate e valutate.
Permette l’implementazione di azioni necessarie a ridurre/eliminare i
guasti/scarti e rilavorazioni.
Permette di associare i guasti ai modi di guasto e alle cause.
Permette di valutare metodi alternativi di produzione.
Permette di ridurre/eliminare problemi di produzione.
Migliora la qualità, l’affidabilità e la sicurezza del prodotto o del
servizio.
Rafforza l’immagine e la competitività dell’azienda.
Massimizza la soddisfazione del cliente.
Aiuta ad individuare il progetto ottimo.
Aiuta ad individuare la ridondanza del sistema.
Aiuta ad identificare caratteristiche critiche/significative.
46!
•
•
•
•
Aiuta nell’analisi di un nuovo processo di produzione e/o di
assemblaggio.
Aiuta l’identificazione e la prevenzione di errori.
Stabilisce una scala di priorità di azioni nel miglioramento del progetto.
Identifica sistematicamente le relazioni tra causa ed effetto.
I possibili punti deboli sono:
•
•
•
•
•
•
L’implementazione di una FMEA può essere costosa e time-consuming
(Rausand, 2005).
È molto facile commettere errori di tipo umano durante l’analisi
(Rausand, 2005).
La metodologia non è adeguata per un numero elevato di modi di guasto
(Rausand, 2005).
Può diventare complicata e ingovernabile a meno che non vi sia una
relazione diretta tra causa ed effetto.
Stabilire una scala di priorità dei modi di guasto in alcuni casi è
complicato dall’esistenza di fattori tra loro contrastanti.
I dati possono essere numerosi anche per sistemi molto semplici.
Dall’analisi dei pro e contro si comprende che la FMEA rappresenta un ottimo
strumento non solo di prevenzione, in quanto identifica i potenziali rischi prima
che giungano al cliente, ma di effettiva correzione delle anomalie in base al
grado di priorità del rischio definita dal valore di RPN. Tuttavia, analizzando i
punti deboli di tale metodologia, in alcuni casi può risultare sconveniente data la
forte componente soggettiva nell’attuazione di un progetto FMEA. È lo stesso
team, infatti, ad assegnare i valori ai parametri di severity, occurence e
detection; il punto critico di una FMEA può essere individuato nell’efficacia
correlata alla qualità delle valutazioni soggettive. Tale rischio di non oggettività
può essere però mitigato da standard identificati e usati dalle aziende.
!
47!
4 FMECA CON PROMIS
!
!
Come già anticipato PROMIS è un software di supporto per molte funzioni
aziendali tra le quali la gestione preventiva e correttiva della manutenzione.
In particolare in questo capitolo andremo ad analizzare la metodologia FMECA
e vedremo come può essere facilmente applicata e gestita da personale non
qualificato utilizzando il software PROMIS.
La FMECA inizialmente è stata pensata come metodologia di studio
affidabilistico a supporto di sistemi complessi. Più recentemente ha trovato
ampio spazio di applicazione in altri ambiti di utilizzo tra i quali troviamo
l’analisi di processo e la manutenzione industriale.
4.1 Tipologie di FMECA e campi di applicazione
Prima di procedere con l’elencare e definire le varie tipologie di FMECA è utile
ricordare che non esiste un’unica forma universalmente valida e accettata. Ogni
FMECA si adatta al settore considerato ed alle esigenze specifiche
dell’organizzazione al fine di massimizzare la soddisfazione del cliente.
Fatta questa premessa procediamo alla descrizione dei quattro tipi di FMECA
più diffusi:
• System FMECA
• Design FMECA
• Process FMECA
• Service FMECA
!
Figura'4.1.'Differenti'tipologie'di'FMECA'
48!
!
•
System FMECA: utilizzata per analizzare sistemi completi o
sottoinsiemi nelle loro fasi iniziali di concezione e progettazione (viene
in alcuni casi chiamata Concept FMECA).
Il System FMEA si focalizza su modi di guasto che hanno origine da
inefficienze del sistema. L’obiettivo principale è quello di stabile un
appropriato bilanciamento fra fattori operativi (legati all’efficacia e alla
produttività) e fattori economici.
•
Design FMECA: è una tecnica analitica utilizzata da un tecnico
responsabile/gruppo di progettazione come strumento per garantire che,
per quanto possibile, i modi di guasto conseguenti a difetti di progetto
siano presi in considerazione e risolti. La Design FMECA affianca
quindi il processo di progettazione riducendone il rischio di anomalie,
fornendo riferimenti per il futuro, ossia lezioni apprese utili per l’analisi
dei settori interessati, per la valutazione delle modifiche e per lo sviluppo
di progetti avanzati.
L’obiettivo del design FMECA è di definire e dimostrare soluzioni
d’ingegneria tenendo in considerazione il fabbisogno funzionale definito
dal System FMEA e dal cliente.
L’attuazione di una design FMECA parte dal presupposto che il sistema
in cui opera sia il migliore possibile, se cosi non fosse il team FMEA
dovrebbe eseguire contemporaneamente sia il System che il Design
FMECA. Implementare simultaneamente le due tecniche però, porta
spesso ad un corto circuito e all’impossibilità di raggiungere il fine
prefissato. L’utilizzo simultaneo delle due tecniche sarà dunque possibile
solo se le cause dei guasti del progetto sono determinate da fattori del
sistema.
•
Process FMECA: è una tecnica analitica utilizzata dal gruppo
competente o dal tecnico responsabile della produzione/assemblaggio
come strumento per garantire che, per quanto possibile, i modi di guasto
collegati al processo o al prodotto siano stati presi in considerazione e
risolti. La Process FMECA è un documento “vivo” che tiene in
considerazione tutte le operazioni e i cambiamenti del processo
produttivo, dai singoli componenti ai complessivi. Il suo obiettivo è di
ottenere un prodotto finale che rispetti le specifiche del progetto e le
aspettative del cliente, intervenendo sul processo produttivo e non sul
progetto. Risulterà quindi fondamentale, al fine di minimizzare gli effetti
dei guasti, avere una visione completa e trasversale del progetto e del
processo produttivo in generale.
49!
•
Service FMECA: utilizzata per esaminare i servizi prima che questi
raggiungano il cliente. Questa tecnica si focalizza sui modi guasti causati
da anomalie del sistema o del processo. L’obiettivo è definire,
dimostrare e massimizzare le soluzioni in risposta alla qualità,
affidabilità, costo e produttività definita dalle specifiche di progetto e dal
cliente. Lo scopo è dunque produrre un prodotto che rispecchi o
addirittura ecceda le caratteristiche qualitative e di sicurezza del servizio
desiderato.
•
Machinery FMECA o Maintenance FMECA: nata negli ultimi anni la
machinery FMECA può essere considerata come una variazione della
design FMECA con focus sulla affidabilità e sicurezza. Viene utilizzata
per analizzare macchinari, attrezzature e strumenti. L’obiettivo
principale è quello di migliorare l’affidabilità e la manutenibilità delle
macchine durante il loro ciclo di vita.
La principale differenza con la Design FMECA (da cui deriva) è che la
M-FMECA si focalizza sull’affidabilità mentre la seconda sulla reale
disponibilità dell’intero impianto.
Essendo PROMIS un software di supporto alla manutenzione, nella seguente
trattazione, si andranno ad analizzare la Design e la Machinery FMECA.
Figura'4.2.''Applicazione'della'FMECA'lungo'il'ciclo'di'lancio'di'un'prodotto'
!
!
!
50!
4.2 Sviluppo metodologia FMECA utilizzando il
Software PROMIS
Come già largamente esposto nel Cap.1, uno dei principi di fondo della
formazione in rete è la “modularità” ovvero la suddivisione dei contenuti
dell’apprendimento in moduli didattici di facile comprensione.
PROMIS permette di suddividere i contenuti didattici tramite l’utilizzo di una
piramide tridimensionale a tre facce.
Le tre facce laterali della piramide sono ulteriormente scomposte in celle per
facilitare la suddivisione dei contenuti.
Figura'4.3.'Esempio'di'piramide'PROMIS'
Per lo sviluppo della metodologia FMECA è stato pensato di effettuare una
prima suddivisione in:
• Design FMECA
• Machinery FMECA
• More Information
!
51!
!
Figura'4.4.'Le'tre'facce'della'piramide'FMECA'
Come si può osservare nella figura 4.3, Ogni lato della piramide è suddiviso in
una griglia da cinque righe e tre colonne per un totale di 15 celle.
È stato quindi deciso di suddividere la trattazione della Design FMECA così
come anche quella della Machinery FMECA nei seguenti livelli:
•
•
•
•
•
Introduction
Preparation
FMECA Procedure
Filling Worksheet
Risk Analysis
Per ogni livello sono quindi previste tre aree:
•
•
•
Methodology
Tools
Templates and Scales
Nella terza piramide (More Information) troviamo link esterni che molto utili
per eventuali approfondimenti.
Nella trattazione che segue verrà data una breve descrizione del contenuto di
ogni cella delle tre piramidi. Per maggiori dettagli è possibile consultare gli
allegati.
!
52!
4.3 Design FMECA
Si parte ora con la descrizione del lavoro svolto il cui fine era quello di ottenere
una schematizzazione facilmente attuabile anche da un personale non qualificato
in fatto di FMECA.
Nell’allegato n°1 si trovano i contenuti relativi alla metodologia DesignFMECA.
4.3.1 Methodology
Figura'4.5.'FMECA'methodology
!
!
53!
L’area che riguarda la metodologia è la parte centrale del lavoro svolto,
verranno analizzati nei dettagli tutti i passi necessari per ottenere una efficace ed
efficiente FMECA
4.3.1.1 Introduction
Nella sezione “introduction” viene, in primo luogo, fornita una panoramica sulle
metodologie FMECA in cui vengono descritte le differenti tipologie e i possibili
campi di applicazione. Sono anche descritte le principali parole chiave e i
concetti fondamentali. Per aiutare la comprensione sono forniti anche una serie
di esempi applicativi.
Nella seconda parte, invece, vengono spiegati i principali criteri per la selezione
dei progetti FMECA; e inclusa una tecnica chiamata “Preliminary Risk
Assesment” che utilizza specifici criteri di selezione per individuare i progetti
FMECA più importanti.
Figura'4.6.'Introduction'overview
!
!
54!
FMECA Methodology
INTRODUCTION
What is FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Figura'4.7.'Introduction'Index'
!
!
!
La sezione “introduction” è stata suddivisa delle seguenti parti:
!
•
What is FMECA: Si forniscono definizioni e descrizioni della
metodologia.
•
Types of FMECA: Si introducono le principali tipologie di FMECA e
vengono descritte più in dettaglio Design e Machinery FMECA
evidenziandone analogie e differenze.
•
FMECA Objectives: Si descrivono gli obiettivi che ogni FMECA deve
perseguire al fine di un corretto sviluppo della metodologia.
•
What can FMECA used for: Vengono presentati i possibili scenari di
applicazione della FMECA.
•
Standards and Guidelines: Elenco degli standard e le linee guida su cui
si basa l’intera metodologia FMECA.
•
When to perform a FMECA: breve analisi per decidere quando iniziare
una nuova FMECA.
55!
•
Definition and Examples: Questa parte copre le definizioni base per
comprendere i concetti fondamentali della FMECA. Viene inoltre fornito
per ogni definizione un esempio applicativo.
•
Preliminary Risk Assessment:! Poiché!effettuare!una!FMECA!per!ogni!
sotto:sistema! ! o! componente! può! essere! molto! dispendioso! sia! in!
termini!di!costi!che!di!tempo,!viene!fornito!un!metodo!utile!per!dare!
una!priorità!ad!ogni!progetto!FMECA.!
!
!
!
4.3.1.2 Preparation
Una preparazione adeguata è essenziale per il successo di ogni progetto
FMECA. In questa sezione vengono descritte passo-passo le attività che devono
essere fatte una volta sola per tutti i futuri progetti FMECA e le attività che
devono essere fatte per ogni singolo nuovo progetto FMECA.
Design-FMECA Methodology
INTRODUCTION
PREPARATION
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Figura'4.8'Preparation'Index
!
!
56!
La sezione “Preparation” è stata suddivisa nelle seguenti parti:
"
"
!
Task done once for all FMECA projects:
•
FMECA Software Selection: Avere il Software giusto può migliorare
notevolmente la qualità e la tempistica del progetto FMECA.
•
Selecting or Modifying FMECA Worksheets and Scales: A questo
punto il Team FMECA deve concordare le norme da seguire. Se lo
standard FMECA non è imposto, Automotive Action Group
(AIAG)fornisce un buon punto di partenza con una descrizione utile
della procedura, delle colonne del foglio di lavoro e delle scale di
classificazione del rischio.
•
Identifying Roles and Responsibilities: Non vi è alcun modello che
definisce i ruoli e le responsabilità specifiche per lo svolgimento dei
compiti della FMECA. Tuttavia vengono fornite delle linee guida e una
checklist mirate ad una buona ed efficiente attribuzione dei ruoli
all’interno della FMECA.
•
Defining the System Hierarchy: Tutti i prodotti, i macchinari e le
attrezzature di ogni tipo hanno una gerarchia di sistema. È molto
importante per i componenti del Team FMECA capire la struttura e la
scomposizione gerarchica del sistema, sotto-sistema o componente in
esame.
•
Access to Failure Information: Il team FMECA deve avere facile
accesso a tute le informazioni che riguardano l’identificazione di
modalità di guasto e relative cause.
Preparation Tasks For Each New FMECA Project:
•
Determine the scope of the analysis: Il prossimo passo è quello di
determinare i confini del progetto FMECA. È importante mettersi
d’accordo sull’ambito della FMECA prima di iniziare. Insieme confini è
essenziale includere le interfacce tra sottosistemi o componenti
adiacenti.
•
Make the scope visible: Al fine di rendere chiaro e visibile il sistema,
sottosistema, o componente in analisi vengono forniti alcuni strumenti
57!
utili come Block Diagram, Interfaces Matrix e Functional Block
Diagram.
!
•
Assemble the correct team: Uno degli step principali nella
preparazione di una FMECA è la selezione del giusto Team. È
sconsigliato fare una FMECA da soli o con un Team incompleto e
inevitabilmente si traduce in scarsa qualità del risultato.
•
Ground rules and assumption: Prima di iniziare l’analisi, il team
dovrebbe discutere e documentare le ipotesi alla base della FMECA e le
regole specifiche sulla sua implementazione. Alcune di queste linee
guida possono essere state determinate precedentemente seguendo le
procedure standard, altre possono specifiche per il progetto in analisi.
•
Establish the role of suppliers: Una parte della preparazione di una
FMECA comprende la determinazione del ruolo dei fornitori. Molti
degli elementi nella gerarchia del sistema possono essere stati progettati
e/o realizzati da fornitori esterni e nelle parti del fornitore possono avere
origine le cause di importanti modalità di guasto. Pertanto il Team
FMECA deve cercare di coinvolgere il fornitore per i componenti critici.
•
Gather and Review Relevant Information: Un altro step importante
nella preparazione di una FMECA è la raccolta di tutti i documenti e le
informazioni rilevanti. Se questo passaggio viene saltato o fatto in
maniera inadeguata, durante le riunioni del Team ci saranno problemi
riguardanti informazioni mancanti.
58!
4.3.1.3 FMECA Procedure
Non appena i vari step della preparation sono completati, si può procedere con
la procedura FMECA vera e propria.
In questa sezione viene descritta la procedura di base per l’implementazione di
una FMECA, a partire dagli items fino al calcolo del Risk Priority Number,
spiegando accuratamente ogni passo della sequenza. Inoltre per ogni fase
vengono forniti esempli esplicativi.
Design-FMECA Methodology
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
Figura'4.9.'FMECA'procedure'Index'
!
!
!
La sezione “FMECA Procedure” è stata suddivisa nelle seguenti parti:
!
•
Sequence of steps: Sono elencati gli steps principali della procedura
anche se non esiste un metodo standard per compilare la tabella
FMECA.
•
Item: Il Team FMECA identifica o conferma il sistema, sottosistema o
componente su cui implementare la FMECA. Dovranno essere
59!
identificate tutte le interfacce tra l’item in questione ed il resto del
sistema.
!
•
Function: Per ogni item in esame, il team FMECA identifica le funzioni
primarie.
•
Failure Modes: Per ogni funzione primaria il team FMECA identifica i
modi di guasto.
•
Effects: Per ogni modo di guasto il team FMECA elenca gli effetti. In
base allo standard FMECA utilizzato si parla di effetto locale, effetto sul
prossimo livello della gerarchia di sistema e effetto finale.
•
Severity Ranking: Dopo aver identificato il più serio degli effetti per
ogni modo di guasto, il team FMECA ne valuta la severity.
•
Causes and Failure Mechanisms: Per ogni modo di guasto il team
FMECA ne identifica le cause. Ci possono essere una o più cause per
ogni modo di guasto. A livello di componente, le cause possono essere
ulteriormente analizzate attraverso la comprensione dei meccanismi di
guasto.
•
Occurrence Ranking: Per ogni causa il team FMECA ne valuta
l’Occurrence.
•
Controls: Per ogni causa, il team FMECA identifica i tipi di controllo.
Ovvero tutte quelle attività già in atto per ridurre o eliminare il rischio.
•
Detection Ranking: Per ogni causa il team FMECA ne valuta la
Detection. Ovvero la probabilità che gli attuali controlli siano in grado di
rilevare la causa del guasto.
•
Risk Priority Number: Per ogni item il team FMECA valuta il Risk
Priority Number. L’RPN consiste nel prodotto aritmetico degli indici
S(severity), O(occurrence) e D(detection).
•
FMECA Linkages: Un Design Verification Plan (DVP) documenta la
strategia che verrà adottata per verificare e garantire che un determinato
item soddisfi le specifiche di progetto o altri requisiti.
60!
4.3.1.4 Filling Worksheet
In questa sezione viene presentato il foglio di lavoro con le istruzioni per la sua
corretta compilazione.
Per ogni cella viene fornita una breve descrizione e in alcuni casi qualche
esempio esplicativo.
Design-FMECA Methodology
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Figura'4.10'Filling'Worksheet
!
!
61!
FILLING WORKSHEET
Design-FMECA Template
(8)
(1)
(4)
(2)
(2A)
(5)
(6)
(9)
(3)
(7)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
(17)
(18)
(19) (20)
Part name
(21)
(22)
(23)
(24)
!
Figura'4.11''Design'FMECA'Template
4.3.1.5 Risk Analysis
Una volta che il team FMECA ha eseguito l’analisi fino alla determinazione del
Risk Priority Number, può iniziare la parte di definizione ed esecuzione delle
azioni correttive.
In questa sezione si spiega come dare priorità agli interventi correttivi, si illustra
come identificare e attuare le strategie di intervento più efficaci e vengono
forniti strumenti fondamentali per la rimozione degli ostacoli che non
consentono una corretta esecuzione della FMECA
!
62!
Design FMECA Methodology
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
Documentation Actions
Taken
Figura'4.12.'Risk'Analysis'Index
!
La sezione “Risk Analysis” è stata suddivisa nelle seguenti parti:
!
•
Prioritize issues for corrective actions: A questo punto il team
FMECA deve decidere quali modalità di guasto andare ad affrontare
prima. È meglio cominciare questa fase soltanto dopo aver calcolato gli
RPN per tutte le modalità di guasto.
•
Develop effective recommended actions: Il team FMECA rivede
ognuno dei modi di guasto con alta Severity e alto RPN, e sviluppa
azioni correttive che, quando eseguite ridurranno il rischio fino ad un
livello accettabile. Molto spesso ci può essere bisogno di più di una
azione correttiva per far diminuire il rischio associato ad un tipo di
guasto.
•
Action strategies to reduce risk: Il team FMECA può utilizzare una
serie di strategie ormai ampliamente collaudate per la gestione del
rischio associato ad alta Severity, Occurrence, Detection.
63!
o Severity Ranking: Vengono descritte alcune strategie per
diminujuire la Severity.
o Occurrence Ranking: Vengono descritte alcune strategie per
diminujuire la Occurrence.
o Detection Ranking: Vengono descritte alcune strategie per
diminujuire la Detection.
•
FMECA execution enablers: Una volta che tute sono state identificate
tutte le azioni correttive, è il momento di metterle in pratica. Vengono
quindi elencati una serie di elementi chiave per garantire la tempestiva
esecuzione delle azioni raccomandate.
•
Documentation actions taken: Il team FMECA documenta tutte le
azioni raccomandate che sono state effettuate al fine di portare il rischio
ad un livello accettabile.
4.3.2 Insights
Nell’area “Insights” si trova del materiale d’ausilio per un corretto svolgimento
della metodologia FMECA. Per ogni livello viene quindi fornito del materiale
integrativo che può essere usato o meno dal responsabile FMECA.
In allegato 3 sono presenti i contenuti completi.
4.3.2.1 Terminology
Come la maggior parte delle metodologie, la FMECA ha una propria
terminologia. La sezione Terminology si trova al livello Preparation dal
momento che, chiaramente, è importante comprendere appieno i termini prima
di intraprendere l’analisi.
!
64!
Figura'4.13.'Terminology'Overview'
!
!
4.3.2.2 Analisi di Pareto
Al livello “FMECA Procedure” troviamo l’analisi di Pareto, una metodologia
statistica utilizzata per individuare i problemi più rilevanti nella situazione in
esame e quindi le priorità di intervento.
L'obiettivo del diagramma è rappresentare in modo efficace i dati più importanti
per concentrare l’attenzione su di essi.
Il segreto del successo in ogni campo di intervento risiede infatti nell'avere
poche e chiare priorità sulle quali intervenire.
L’analisi di Pareto può essere facilmente applicata alla metodologia FMECA al
fine di dare una priorità ai vari progetti FMECA.
Figura'4.14.Pareto'Analysis'Overview
!
!
65!
4.3.2.3 Fault Tree Analysis
La Fault Tre Analysis (FTA) può essere identificata come un processo di analisi
di un sistema, in grado di evidenziare le cause di eventi di più basso livello che,
direttamente o indirettamente, contribuiscono ad una causa più rilevante, o in
ultimo al top event. La sua importanza risiede nel fatto che, una volta ultimato e
letto in senso Down-Top, è in grado di fornire un’analisi completa del sistema
attraverso lo sviluppo dei failure mechanisms di più basso livello fino al Top
Event.
La FTA può essere usata come strumento di supporto alla FMECA in tutti quei
casi in cui l’ipotesi di indipendenza delle cause e dei meccanismi di guasto è
violata.
Figura'4.15.'FTA'Overview
!
4.3.2.4 FMECA Forms
A seconda dello standard FMECA selezionato e dalle esigenze individuali si
può scegliere tra una serie di differenti schede FMECA.
Al livello “Filling Worksheet” troviamo una breve descrizione d’ausilio alla
creazione di una scheda FMECA, inoltre vengono presentate e descritte le più
diffuse ed utilizzate in ambito industriale.
!
66!
!
Figura'4.16.'FMECA'Forms'Overview'
!
4.3.2.5 More about risk Analysis
In questa sezione si trovano due strumenti molto utili per l’ultima fase della
metodologia FMECA, ovvero l’analisi di rischio.
•
•
Criticality Analysis: una procedura che classifica il rischio associato ad
ogni modalità di guasto in base all’influenza combinata di severità e
probabilità di occorrenza.
FMECA Quality Audit: osservando gli errori più comuni che vengono
fatti durante l’implementazione della FMECA si può imparare molto e
cercare di evitarli. La FMECA Quality Audit consiste nell’effettuare
revisioni di FMECA completate e per ogni errore individuare gli
obiettivi di qualità che non sono stati raggiunti. Inoltre per ogni “Audit”
è fornito un esempio esplicativo.
Figura'4.17.More'about'risk'analysis'overview
!
!
67!
4.3.3 Templates, Scales and Checklists
In quest’area si trova dell’altro materiale integrativo sotto forma di tabelle,
schede e checklist. Ancora una volta si sottolinea che tutto il materiale
integrativo proposto può essere usato o meno a discrezione di quelle che sono le
esigenze del responsabile FMECA e/o del singolo progetto FMECA.
In allegato 4 si trovano i contenuti completi
4.3.3.1 Preparation Checklists
Al livello Preparation troviamo le seguenti Checklists:
•
•
•
FMECA Preparation Checklist
Gather Information Checklist
Ready for the first meeting checklist
Figura'4.18.'Preparation'Checklist'overview
!
!
68!
4.3.3.2 FMECA Procedure Checklists
Al livello FMECA Procedure troviamo le seguenti checklists:
•
•
Checklist of function type
Five Whys
Figura'4.19.'FMECA'Procedure'checklists'overview
!
4.3.3.3 Filling Worksheet Template and Scales
Al livello Filling Worksheet troviamo:
•
•
•
•
!
Design FMECA Template
Severity Scale
Occrence Scale
Detection Scale
69!
!
Figura'4.20.''Filling'Worksheet'Tmplate'and'Scales'overview
4.3.3.4 More about Recommended Actions
Al livello Risk Analysis troviamo un breve elenco di risorse utili in termini di
qualità ed affidabilità per la ricerca e lo sviluppo di efficaci azioni correttive.
Figura'4.21.'More'about'recommended'actions'overview.'
!
!
70!
4.4 Machinery FMECA
Per quanto riguarda la Machinery FMECA (o Maintenance FMECA), essa si è
affermata come strumento d’elezione per:
•
•
•
L’analisi delle modalità di guasto di un’entità complessa
L’identificazione dei suoi elementi critici dal punto di vista
affidabilistico
La definizione ragionata del piano di manutenzione a partire dai
componenti critici.
Figura 4.22. Machinery FMECA con PROMIS
Dal punto di vista metodologico e della distribuzione dei contenuti all’interno
della Piramide non vi è alcuna differenza con la Design FMECA descritta nel
paragrafo precedente. Le uniche differenze riguardano alcuni contenuti e, in
particolare:
•
•
•
Scheda FMECA
Scale di Severity, Occurrence e Detection
Esempi esplicativi
I contenuti completi si trovano in allegato 4.
!
71!
4.5 More Information
Come già anticipato la metodologia FMECA non segue regole rigide ma può
essere modificata a discrezione del responsabile FMECA o del Team FMECA.
Per questo motivo nella terza e ultima piramide viene proposta una serie di link
esterni molto utili per approfondire ogni passo della metodologia FMECA.
Figura 4.23. terzo lato della piramide PROMIS
Per quanto riguarda la suddivisione dei contenuti all’interno della piramide,
troviamo cinque livelli corrispondenti a:
•
•
•
•
•
Bibliografia
Articoli
Linee guida
Standard
Software
Ogni livello, quando possibile è stato suddiviso in tre sezioni riguardanti:
•
•
•
!
Industria di processo
Industria manifatturiera
Industria su commessa
72!
4.5.1 Bibliografia
Al livello “bibliografia” troviamo i testi bibliografici consigliati e a cui fare
riferimento per eventuali approfondimenti.
Figura 4.24. Bibliografia consigliata
!
73!
4.5.2 Articoli
Al livello “articoli” troviamo una serie di articoli riguardanti l’applicazione della
metodologia FMECA. In questo caso è stata effettuata la suddivisione tra:
•
Industria di Processo
Figura 4.25. Articoli riguardanti la FMECA applicata all’industria di processo
•
Industria manifatturiera
Figura 4.26. Articoli riguardanti la FMECA applicati all’industria manifatturiera.
!
74!
•
Industria su commessa.
Figura 4.27. Articoli riguardanti la FMECA applicati all’industria su commessa
4.5.3 Linee Guida
In questo livello si trovano le principali linee guida consigliate per un corretto
svolgimento della FMECA, anche in questo caso suddivise per tipologia
industriale.
•
Industria di processo
Figura 4.28. Linee guida per l’industria di processo
!
75!
•
Industria manifatturiera
Figura 4.29. Linee guida per l’industria manifatturiera
•
Industria su commessa
Figura 4.30. Linee guida per l’industria su commessa
!
76!
4.5.4 Standard
Al livello “standard” sono presenti i vari standard che possono essere seguiti o
meno dal personale adibito all’implementazione della FMECA. Anche in questo
caso suddivisi nelle 3 sezioni:
•
Industria di processo
Figura 4.31 Standard per l’industria di processo
•
Industria manifatturiera
Figura 4.32. Standard per l’industria manifatturiera
!
77!
•
Industria su commessa
Figura 4.33. Standard per l’industria su commessa
4.5.5 Software
Infine all’ultimo livello della piramide troviamo una panoramica sui principali
software FMECA sul mercato classificati in base al budget che si è disposti a
spendere.
Figura 4.34. FMECA Soft
!
78!
5 Conclusioni e sviluppi futuri
L’obiettivo di questa tesi era quello di creare uno strumento di formazione
continua nell’ambito manutentivo, applicato alla metodologia FMECA. In
particolare si è partiti dall’esigenza semplificare i vari passi della metodologia al
fine di renderla il più semplice e comprensibile possibile e direttamente fruibile
dal personale addetto alla manutenzione. Senza pertanto passare attraverso corsi
di formazione e/o corsi di aggiornamento molto più onerosi in termini di tempi
e di costi.
Poiché una delle più rilevanti sfide per il mondo della formazione è dimostrare
la capacità di stare al passo con la rapidità alla quale l’informazione circola e
diviene obsoleta, l’aggiornamento immediato e affidabile delle conoscenze è
quindi una questione vitale. Inoltre chi lavora ha bisogno di soluzioni flessibili
che si adattino ai ritmi dell’attività di lavoro e dell’apprendimento: il tempo
sottratto al lavoro e i costi organizzativi hanno un ruolo sempre più decisivo
nelle scelte dei decisori e dei consumatori dei servizi formativi.
In tal senso il software promis si è rivelato uno strumento molto utile poiché
permette la scomposizione e la modularità dei contenuti che, oltretutto, possono
essere modificati e aggiornati in tempo reale.
Tuttavia ricordando che l’obiettivo di un qualsiasi strumento formativo è quello
di formare l’utente e, in questo specifico caso il personale addetto alla
manutenzione, il lavoro di tesi non può dirsi completo fino a quando non ne
verranno dimostrate l’efficacia e l’efficienza.
A tal proposito, uno dei possibili sviluppi futuri potrebbe essere quello di testare
le funzionalità del software su un certo numero di utenti per valutarne
l’apprendimento. Oppure quello confrontare l’apprendimento degli utenti online con quelli formati in maniera tradizionale e trarne le rispettive conclusioni.
Come già detto PROMIS permette la modifica dei contenuti in maniera quasi
istantanea quindi potrà sicuramente essere migliorato subito dopo i primi test.
!
79!
Bibliografia e sitografia
!
•
Kevin A. Lange, Steven C. Leggett, Beth Baker, “Potential Failure Mode
and Effects Analysis: Reference Manual”, DaimlerChrysler Corporation,
Ford Motor Company, General Motors Company; third edition, 2001.
•
Stamatis D. H. ,“Fmea: from theory to Execution”, ASQC Quality Press,
2006.
•
Mc Dermott E., Mikulak J., Beauregard R., “The basics of FMEA”,
Productivity Press, second edition, 1996.
•
Dana Crowe, Alec Feinberg, “Design for Reliability”, 2001.
•
Carl S.Carlson, “Effective FMEAs”, 2012.
•
Eric Ries, “Partire leggeri”.
•
AIAG, 2008, Advanced Product Quality Planning and Control Plan
(APQP), AIAG.
•
Military, United States, 1980, MIL-STD-1629A: Procedures for
Performing A Failure Mode Effects And Criticality Analysis,
Department of Defense.
•
Military, United States, 2006, Failure Modes, Effects and Criticality
Analysis (FMECA) for Command, Control, Communications, Computer,
Intelligence, Surveillance, and Recon- naissance (C4ISR) Facilities,
Headquarters, Department of Army.
•
SAE, 2001, SAE ARP5580: Recommended Failure Mode and Effects
Analysis (FMEA) Practices for Non-Automotive Applications, copyright
2001 SAE International.
•
DFR Fundamentals: An Introduction to Design for Reliability. 2007.
ReliaSoft Corpora- tion.RS 560 DFR Fundamentals, Copyright ReliaSoft
Corporation.
•
AIAG, 2008, Potential Failure Mode and Effects Analysis (FMEA) 4th
Edition.
•
Levin, Mark and Kalal Ted, Improving Product Reliability: Strategies
and Implementation. John Wiley & Sons, 2003.
•
Derating for electrical components. Reliability HotWire: The eMagazine
for the Reliability Professional. ReliaSoft Corporation, October 2008.
80!
Issue 92. Available at http://www.
!
•
Sull, Donald and Charles Spinosa, Promise-based management: The
essence of execution. Harvard Business Review. April 1, 2007.
•
SAE, 2009, SAE J1739 JAN2009 Potential Failure Mode and Effects
Analysis in Design (Design FMEA).
•
NASA, 2002, Fault Tree Handbook with Aerospace Applications,
NASA Office of Safety and Mission Assurance.
•
Fault Tree Analysis: An Overview of Basic Concepts. ReliaSoft
Corporation. Reliability Engineering Resources. Available at
http://www.weibull.com/basics/fault-tree/index.htm.
•
Spiceland J. D. (2002), An as- sessment of the effectiveness of elearning in corporate training programs, International Review of
Research in Open and Distance Learning, vol.3, n.1.
•
La Noce F. (2001), E-learning. La nuova frontiera della formazione,
Franco Angeli, Milano.
•
iCDL International Centre for Di- stance Learning, http://wwwicdl.open.ac.uk/
•
http://www.tdmagazine.itd.cnr.it/files/pdfarticles/PDF33/favretto.pdf
•
http://www.sre.org/pubs/MIl-Std-785B.pdf
•
http://www.e-learningsite.com/download/white/lcms-idc.pdf
•
www.fmeainfocenter.com
•
www.aiag.org
•
www.gm.com
•
www.camozzi-manufacturing.it
•
http://www.ptm-consulting.it/pharma-quality-risk-management.aspx
81!
1 ALLEGATO - Design FMECA
1.1 Introduction
INTRODUCTION
FMECA Methodology
What is FMECA ?
INTRODUCTION
INTRODUCTION
What is FMECA?
What is FMECA?
Types of FMECA
Types of FMECA
FMECA Objectives
FMECA Objectives
What can FMECA be
used for?
What can FMECA be
used for?
Standards and Guidelines
Standards and Guidelines
When to perform an
FMECA
When to perform an
FMECA
Definitions and
Examples
Definitions and
Examples
Preliminary Risk
Assessment
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
1"
RISK ANALYSIS
Failure modes, effects and criticality analysis (FMECA) is a
methodology to identify and analyze:
•  All potential failure modes of the various parts of a system
•  The effects these failures may have on the system
•  How to avoid the failures, and/or mitigate the effects of the failures
on the system
“FMECA is a technique used to identify, prioritize, and eliminate
potential failures from the system, design or process before they reach
the costumer”
Omdahl (1988)
“FMECA is a technique to resolve potential problems in a system
before they occur”
Sematech (1992)
2"
RISK ANALYSIS
INTRODUCTION
INTRODUCTION
What is FMECA ?
Types of FMECA
INTRODUCTION
What is FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
INTRODUCTION
•  An FMECA is an engineering analysis done by a cross-functional
team of subject matter experts that thoroughly analyzes product
designs early in the product development process. Its objective is
finding and correcting weaknesses before the product gets into the
hands of the customer.
•  An FMECA should be the guide to the development of a complete
set of actions that will reduce risk associated with the system,
subsystem, and component or manufacturing/assembly process to
an acceptable level.
•  If effectively used throughout the product life cycle, it will result in
significant improvements to reliability, safety, quality, delivery, and
cost.
3"
RISK ANALYSIS
What is FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
Design
Components
Components
Subsystems
Subsystems
Main
systems
Main
systems
Human
resources
Task
Work station
Service lines
Services
Performance
Operators
training
Process
Manpower
Machine
Method
Material
Measurement
Environment
Machinery
Focus on
Tools
Work station
Production
lines
Processes
Gauges
Operators
training
4"
INTRODUCTION
Types of FMECA
Types of FMECA
INTRODUCTION
INTRODUCTION
What is FMECA?
What is FMECA?
Types of FMECA
Types of FMECA
FMECA Objectives
FMECA Objectives
What can FMECA be
used for?
What can FMECA be
used for?
Standards and Guidelines
Standards and Guidelines
When to perform an
FMECA
When to perform an
FMECA
!
System
RISK ANALYSIS
INTRODUCTION
Definitions and
Examples
Definitions and
Examples
Preliminary Risk
Assessment
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Service
Manpower
Human
resources
Machine
Method
Material
Measurement
Environment
5"
RISK ANALYSIS
Design FMECAs should be done at the subsystem and/or component
level when new designs begin development or when existing designs
will be changed sufficiently so that there are concerns about risk.
Is used to analyze products, high volume tools or standard machines,
machine components, standard production tooling, etc., before they
are released to production.
•  Focuses on potential failure modes of products caused by design
deficiencies.
•  Focuses on parts that can be prototyped and tested or modeled
before high volume production of the product is launched.
6"
82!
INTRODUCTION
INTRODUCTION
Types of FMECA
Types of FMECA
INTRODUCTION
What is FMECA?
Types of FMECA
INTRODUCTION
Machinery FMECAs are treated as a variation of a design FMECA.
The predominant focus on this variation is on identifying safety and
reliability issues.
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
What is M-FMECA?
Types of FMECA
FMECA Objectives
FMECA Objectives
Is used to analyze low-volume specialty machinery (equipment and
tools), that allows for customized selection of component parts,
machine structure, tooling, bearings, coolants, etc.
•  Focuses on designs that improve the reliability and
maintainability of the machinery for long-term plant usage.
•  Considers preventive maintenance as a control to ensure
reliability.
•  Considers limited volume, customized machinery where large
scale testing of a number of machines is impractical prior to
production and manufacture of the machine.
•  Considers parts that can be selected for use in the machine, where
reliability data is available or can be obtained before production
use.
7"
RISK ANALYSIS
The key differences between Design and Machinery FMECA are:
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
•  Product Design FMECAs are intended for high production
systems/subsystems and components. Prototype or surrogate part
testing is used to verify design intent.
•  Machinery FMECAs are used for relatively low volume designs,
where statistical failure data on prototypes is not practical to be
obtained by the manufacturer.
•  Machinery FMECAs are targeted for long-term, repetitive cycles,
where wear out is a prime consideration. For example, machinery
running at two 10-hours shifts per day, 50 weeks per year, will
accumulate 120,000 hours of operation in twenty years. This
would be equivalent to a vehicle being driven 600,000 miles at
an average speed of 50mph.
•  The severity, occurrence, and detection tables used are tailored to
meet the needs of the machinery design engineer in order to
maintain a standard interpretation across a wide variety of
machinery designs.
8"
RISK ANALYSIS
INTRODUCTION
INTRODUCTION
Types of FMECA
FMECA Objectives
INTRODUCTION
What is FMECA?
Types of FMECA
INTRODUCTION
Since the Machinery-FMECA can be considered as a variation of
Design-FMECA focusing on safety and reliability, the following
methodologies will be similar in most of their parts.
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Types of FMECA
What can FMECA be
used for?
•  Filling worksheet
•  Scales
•  Templates
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Definitions and
Examples
Preliminary Risk
Assessment
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
9"
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Identify and prevent safety hazards
Minimize loss of product performance or performance degradation
Improve test and verification
Consider changes to the product design or manufacturing process
Identify significant product or process characteristics
Develop Preventive Maintenance plans for in-service machinery
and equipment
•  Develop online diagnostic techniques
10#
RISK ANALYSIS
INTRODUCTION
FMECA Standards and Guidelines
INTRODUCTION
!  Assist in selecting design alternatives with high reliability and
high safety potential during the early design phases
What is FMECA?
!  Ensure that all conceivable failure modes and their effects on
operational success of the system have been considered
FMECA Objectives
!  List potential failures and identify the severity of their effects
Develop early criteria for test planning and requirements for
test equipment
!  Provide historical documentation for future reference to aid in
analysis of field failures and consideration of design changes
!  Provide a basis for maintenance planning
!  Provide a basis for quantitative reliability and availability
analyses.
11"
Types of FMECA
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
STANDARDS:
!  MIL-STD 1629 “Procedures for performing a failure mode and
effect analysis”
!  IEC 60812 “Procedures for failure mode and effect analysis
(FMEA)”
!  BS 5760-5 “Guide to failure modes, effects and criticality
analysis (FMEA and FMECA)”
!  SAE ARP 5580 “Recommended failure modes and effects
analysis (FMEA) practices for non-automobile applications”
!  SAE J1739 “Potential Failure Mode and Effects Analysis in
Design (Design FMEA) and Potential Failure Mode and Effects
Analysis in Manufacturing and Assembly Processes (Process
FMEA) and Effects Analysis for Machinery (Machinery FMEA)”
!  SEMATECH (1992) “Failure Modes and Effects Analysis
(FMEA): A Guide for Continuous Improvement for the
Semiconductor Equipment Industry”
12#
INTRODUCTION
INTRODUCTION
FMECA Standards and Guidelines
When to perform an FMECA
INTRODUCTION
GUIDELINES:
What is FMECA?
Types of FMECA
• 
• 
• 
• 
• 
• 
INTRODUCTION
RISK ANALYSIS
INTRODUCTION
There are also many other objectives such us:
What can FMECA be used for?
INTRODUCTION
What is FMECA?
The primary objective of an FMECA is to improve the design.
Particularly for Design-FMECA and Machinery-FMECA the main
objective is to improve the design of subsystem or component.
FMECA Objectives
Differences between the two methodologies regard:
RISK ANALYSIS
!
What is FMECA?
What is FMECA?
•  MIL-STD-785, "Reliability Program for Systems and Equipment
Development and Production" This standard imposes the requirement
to perform Task 204, "Failure Mode, Effects and Criticality Analysis." It
gives guidance as to when the task is to be performed and to what depth
it should be done. It does not dictate how the analysis is to be performed.
•  MIL-STD-1543, "Reliability Program Requirements for Space and
Launch Vehicles" This document is similar in many respects to MILSTD-785. imposes the requirement to perform Task 204, "Failure Mode,
Effects and Criticality Analysis." It gives guidance as to when the task is
to be performed and to what depth it should be done but does not dictate
how the analysis is to be performed.
•  NASA NHB 5300.4, "Reliability Program Provisions for
Aeronautical and Space Contractors" This document is similar in
some respects to MIL-STD-785. It imposes the requirement to perform
an FMECA and gives guidance as to when the task is to be performed
and to what depth it should be done but it does not dictate how the
analysis is to be performed.
13#
Types of FMECA
FMECA Objectives
The FMECA should be initiated as early in the design process,
where we are able to have the greatest impact on the equipment
reliability. The locked-in cost versus the total cost of a product is
illustrated in the figure:
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
14#
83!
INTRODUCTION
What is FMECA?
Types of FMECA
INTRODUCTION
INTRODUCTION
When to perform an FMECA
FMECA Definitions and Examples
Figure above describes the increasing costs of finding and fixing
problems depending on when the problems are discovered. The later
problems are found in the product development process, the more it
costs to fix them, symbolized by factors of 10.
INTRODUCTION
What is FMECA?
Types of FMECA
FMECA Objectives
FMECA Objectives
What can FMECA be
used for?
What can FMECA be
used for?
Standards and Guidelines
Standards and Guidelines
When to perform an
FMECA
When to perform an
FMECA
Definitions and
Examples
Definitions and
Examples
Preliminary Risk
Assessment
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
15#
RISK ANALYSIS
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
INTRODUCTION
INTRODUCTION
What is FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Examples of Items:
Item: Power steering pump
Item: Shaft (part of rock grinding equipment)
Item: Projector lamp
Item: Oven burner assembly
Item: Hydraulic fluid tank
Item: Robotic transfer device
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
17#
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
A “function” is what the item is intended to do, usually to a given
standard of performance or requirement.
For Design FMECAs, this is the primary purpose or design intent of
the item; wording should consider “Do this [operation] to this [the
part] with this [the tooling]” along with any needed requirement. There
can be many functions for each item or operation. Functions are
typically described in a verb–noun format.
Examples of Functions:
•  Item: Power steering pump
Function: Delivers hydraulic power for steering by transforming
oil pressure at inlet (xx psi) into higher oil pressure at outlet (yy
psi) during engine idle speed
•  Item: Oven burner assembly
Function: Heat the burner plate to 160°F within 60 seconds
•  Item: Hydraulic fluid tank
Function: Contain the XYZ hydraulic fluid in tank, with no
external leakage per specification #456
18#
RISK ANALYSIS
INTRODUCTION
INTRODUCTION
FMECA Definitions and Examples: Failure Mode
FMECA Definitions and Examples: Effect
A “failure mode” is the manner in which the item or operation
potentially fails to meet or deliver the intended function and associated
requirements.
There may be many failure modes for each function.
Failure modes may include failure to perform a function within defined
limits, inadequate or poor performance of the function, intermittent
performance of a function, and/or performing an unintended or
undesired function.
Examples of Failure Modes:
•  Item: Power steering pump
Function: Delivers hydraulic power for steering by transforming
oil pressure at inlet (xx psi) into higher oil pressure at outlet [yy
psi] during engine idle speed
Failure Mode: Inadequate outlet pressure [less than yy psi]
•  Item: Shaft (part of rock grinding equipment)
Function: Provide mechanical transfer of [xx] rotational force
while maintaining linear and angular stability
Failure Mode: Shaft fractured
19#
INTRODUCTION
What is FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
An “effect” is the consequence of the failure on the system or end user.
Depending on the ground rules for the analysis, the team may define a single
description of the effect on the top-level system and/or end user, or three
levels of effects:
•  Local Effect: The consequence of the failure on the item or adjacent items
•  Next Higher Level Effect: The consequence of the failure on the next
higher level assembly
•  End Effect. The consequence of the failure on the top-level system and/or
end user
Example of Effects:
•  Item: Power steering pump
Function: Delivers hydraulic power for steering by transforming oil
pressure at inlet (xx psi) into higher oil pressure at outlet [yy psi] during
engine idle speed.
Failure Mode: Inadequate outlet pressure [less than yy psi]
Effect (Local: Pump): Low pressure fluid goes to steering gear
Effect (Next level: Steering Subsystem): Increased friction at steering
gear
Effect (End user): Increased steering effort with potential accident
during steering maneuvers.
20#
INTRODUCTION
INTRODUCTION
FMECA Definitions and Examples: Severity
FMECA Definitions and Examples: Cause
“Severity” is a ranking number associated with the most serious effect for a
given failure mode, based on the criteria from a severity scale. It is a
relative ranking within the scope of the specific FMECA.
In the adjacent
figure you can see
an example of
severity scale for
D-FMECA from
the Automotive
industry Action
Group (AIAG).
INTRODUCTION
What is FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
!
What is FMECA?
An “item” is the focus of the FMECA project. For a DesignFMECA, this is the subsystem, for a Machinery-FMECA is the
machine or component under analysis.
RISK ANALYSIS
INTRODUCTION
16#
RISK ANALYSIS
FMECA Definitions and Examples : Function
RISK ANALYSIS
What is FMECA?
•  The definitions are presented in the sequence they are normally
developed in a FMECA project
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
INTRODUCTION
•  The time spent toward understanding the fundamental concepts
and definitions of FMECA will shorten the time in meetings and
help ensure high quality results.
FMECA Definitions and Examples: Item
INTRODUCTION
What is FMECA?
This section covers the basic definitions of FMECA and examples
from different applications.
21#
RISK ANALYSIS
A “cause” is the specific reason for the failure, preferably found by
asking “why” until the root cause is determined. For Design FMECAs, the
cause is the design deficiency that results in the failure mode.
In most applications, particularly at the component level, the cause is
taken to the level of failure mechanism, which is further explained.
By definition, if a cause occurs, the corresponding failure mode occurs.
There can be many causes for each failure mode.
Example of Causes:
• 
Item: Power steering pump
Function: Delivers hydraulic power for steering by transforming oil
pressure at inlet (xx psi) into higher oil pressure at outlet ([yy] psi)
during engine idle speed
Failure Mode: Inadequate outlet pressure (less than [yy] psi)
Effect (Local: Pump): Low pressure fluid goes to steering gear
Effect (Next level: Steering Subsystem): Increased friction at steering
gear
Effect (End user): Increased steering effort with potential accident
during steering maneuvers
Cause: Fluid incorrectly specified (viscosity too low)
22"
84!
INTRODUCTION
What is FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
INTRODUCTION
INTRODUCTION
FMECA Definitions and Examples Occurrence
FMECA Definitions and Examples: Control
“Occurrence” is a ranking number associated with the likelihood that
the failure mode and its associated cause will be present in the item
being analyzed.
For Design FMECAs, the occurrence ranking considers the likelihood
of occurrence during the design life of the product.
The criteria for
these scales
should be
reviewed and
tailored (as
needed) to make
sense for
individual
company
applications!
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Definitions and
Examples
23!
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
INTRODUCTION
FMECA Definitions and Example: Risk Priority Number
What is FMECA?
Types of FMECA
FMECA Objectives
The detection
ranking considers
the likelihood of
detection of the
failure mode/cause,
according to
defined criteria.
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
25#
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
•  severity of the effect
•  likelihood of occurrence of the cause
•  likelihood of detection of the cause.
Use of RPN is further explained
26#
RISK ANALYSIS
INTRODUCTION
INTRODUCTION
FMECA Definitions and Examples: Recommended Actions
FMECA Definitions and Examples: Recommended Actions
“Recommended actions” are the tasks recommended by the FMECA team to
reduce or eliminate the risk associated with potential causes of failure.
Recommended actions should consider the existing controls, the relative
importance (prioritization) of the issue, and the cost and effectiveness of the
corrective action. There can be many recommended actions for each cause.
Examples of Recommended Actions for Design FMECAs
Item: Power steering pump
Function: Delivers hydraulic power for steering by transforming oil
pressure at inlet ([xx] psi) into higher oil pressure at outlet [yy] psi during
engine idle speed
Failure Mode: Inadequate outlet pressure (less than [yy] psi)
Effect (Local: Pump): Low pressure fluid goes to steering gear
Effect (Next level: Steering Subsystem): Increased friction at steering gear
Effect (End user): Increased steering effort with potential accident during
steering maneuvers
Cause: Fluid incorrectly specified (viscosity too low)
Prevention Control: Design guidelines for hydraulic fluid selection Detection
Control: Vehicle durability testing #123
Recommended Action: Increase fluid viscosity to standard #xyz
Poorly worded example of Recommended Action: Change fluid
viscosity
27#
INTRODUCTION
What is FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
Figure: Example of causes, controls and recommended actions for a disk brake
system.
28#
RISK ANALYSIS
INTRODUCTION
INTRODUCTION
Preliminary Risk Assessment
Preliminary Risk Assessment
INTRODUCTION
What is FMECA?
Risk Priority Number (RPN) is a numerical ranking of the risk
of each potential failure mode/cause, made up of the arithmetic
product of the three elements:
Definitions and
Examples
Preliminary Risk
Assessment
FMECA Objectives
24#
INTRODUCTION
“Detection” is a ranking number associated with the best control from
the list of detection-type controls, based on the criteria from the
detection scale.
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
Types of FMECA
Poorly worded example of Prevention Control: Design guide
Poorly worded example of Detection Control: Vehicle durability test
INTRODUCTION
Preliminary Risk
Assessment
What is FMECA?
Examples of Controls:
Item: Power steering pump
Function: Delivers hydraulic power for steering by transforming oil
pressure at inlet ([xx] psi) into higher oil pressure at outlet ([yy] psi) during
engine idle speed
Failure Mode: Inadequate outlet pressure (less than [yy] psi)
Effect (Local: Pump): Low pressure fluid goes to steering gear
Effect (Next level: Steering Subsystem): Increased friction at steering gear
Effect (End user): Increased steering effort with potential accident during
steering maneuvers
Cause: Fluid incorrectly specified (viscosity too low)
Prevention Control: Design guidelines for hydraulic fluid selection
Detection Control: Vehicle durability test #123
RISK ANALYSIS
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
INTRODUCTION
“Controls” are the methods or actions currently planned, or are already in place,
to reduce or eliminate the risk associated with each potential cause. Controls can
be the methods to prevent or detect the cause during product development, or can
be actions to detect a problem during service before it becomes catastrophic.
There can be many controls for each cause.
FMECA Definitions and Examples: Detection
RISK ANALYSIS
!
What can FMECA be
used for?
Preliminary Risk
Assessment
FMECA Objectives
What can FMECA be
used for?
Types of FMECA
FMECA Objectives
When to perform an
FMECA
INTRODUCTION
Types of FMECA
What is FMECA?
Standards and Guidelines
RISK ANALYSIS
What is FMECA?
INTRODUCTION
INTRODUCTION
Doing FMECAs on all subsystem and components can be very
expensive and time consuming, there needs to be a way to prioritize
potential FMECA projects, to help identify which FMECAs to do. One
way to do this prioritization is Preliminary Risk Assessment.
Open up a simple spreadsheet, in the first column, list the complete
subsystem or component hierarchy. Across the top of the spreadsheet
put the risk criteria used to prioritize the risk as described below:
1.  Risk identified by System or Concept FMECA (Does the System or
Concept FMECA point toward risk in the item?). (If done)
What is FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
2.  Potential for safety issues (What is the degree of safety risk
associated with the item?)
3.  New technology (What is the degree of new technology being
introduced with the item?)
29#
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
4.  New applications of existing technology (What is the level of
new application for existing technology with the item?)
5.  History of significant field problems (What level of field
problems has been associated with the item or similar items?)
6.  Potential for important regulation issues (What level of
government regulation is associated with the item?)
7.  Mission-critical applications (To what degree can failures with
the item bring about loss of primary mission?)
8.  Supplier capability (What is the risk associated with the supplier
of the item?)
30#
85!
INTRODUCTION
INTRODUCTION
Preliminary Risk Assessment
Preliminary Risk Assessment
INTRODUCTION
What is FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
The final step uses simple arithmetic to multiply the cells in each
row to obtain a risk index number for each of the subsystems or
components in the system hierarchy. This index can then be used
as input to the FMECA selection decision.
What is FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform an
FMECA
Definitions and
Examples
Definitions and
Examples
Preliminary Risk
Assessment
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
!
INTRODUCTION
The next step is to rank each risk criteria column for each row in
the system hierarchy on a scale of risk, such as high, medium, or
low, or 1–5. In other words, assess the risk for each item of the
component hierarchy according to the risk criteria.
31#
RISK ANALYSIS
Figure shows an example of preliminary risk assessment for a bicycle project.
32#
86!
1.2 Preparation D-FMECA
PREPARATION
Design-FMECA Methodology
Tasks done Once For All FMECA Project
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
Task done once for all
FMECA projects
Task done once for all
FMECA projects
Software Selection
Software Selection
Worksheet and Scales
Worksheet and Scales
Roles and Responsibilities
Roles and Responsibilities
System Hierarchy
System Hierarchy
Failure Information
Failure Information
Preparation Tasks For Each
New FMECA Project
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Role of Suppliers
Gather and Review Relevant
Information
Gather and Review Relevant
Information
FMECA
PROCEDURE
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
FILLING
WHORKSHEET
RISK ANALYSIS
1"
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
PREPARATION
Tasks done Once For All FMECA Project
2 - Selecting or Modifying FMECA Worksheets and Scales
INTRODUCTION
Having the right FMECA software can greatly improve the quality
and timing of FMECA project.
FMECA software needs to be easy to use with an intuitive user
interface, allowing the FMECA team to enter information easily, in
real time, during FMECA meetings. Some of the characteristics of
good FMECA software include:
• 
• 
• 
• 
• 
• 
• 
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
A smooth linkage between system hierarchy
FMECA worksheet
Control plans
Capacity for simultaneous users
Comprehensive search queries
Ability to link all electronic documents
Easily configurable profiles and interfaces
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Software Selection
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Role of Suppliers
3"
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
System Hierarchy
Failure Information
FILLING
WHORKSHEET
RISK ANALYSIS
PREPARATION
INTRODUCTION
•  The criteria for the detection scale must be reviewed and agreed
upon, clearly differentiating the likelihood of detection from very
remote to almost certain. For Design FMECAs, risk related to
detection can also be differentiated based on the timing opportunity
for detection and the type of test used for detection, in addition to
likelihood of detection.
•  If the risk ranking scales are not mandated and the team has the
flexibility to establish their own risk ranking scales, there is a
simple rule to follow: use the minimum number of ranking levels
for each scale that adequately differentiates the risk criteria.
PREPARATION
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Once agreed upon, the FMECA worksheet configuration and the risk
ranking scales should be controlled throughout the company, so that
individual FMECA teams maintain a consistent approach to FMECA
that supports company objectives.
(See also Example FMECA Forms in Tools section)
5"
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
Questions often arise as to who is responsible for the various tasks
associated with FMECA projects and the nature of the responsibilities.
•  Who takes the lead in selecting the FMECA projects or performing
the Preliminary Risk Assessment?
•  Who carries out the FMECA preparation tasks?
•  Who facilitates the FMECA team meetings?
•  Who is ultimately responsible for the FMECA document?
•  Who enters the information into the FMECA database?
•  Who follows up on the execution of FMECA recommended
actions?
•  Who communicates the high-risk issues from FMECAs to
management?
•  Who in management champions the entire FMECA process and
sees to the budget, staffing and other needed resources?
•  Who trains the FMECA team in the basic FMECA procedure?
FILLING
WHORKSHEET
RISK ANALYSIS
6"
PREPARATION
PREPARATION
Tasks done Once For All FMECA Project
3 - Identifying Roles and Responsibilities
Tasks done Once For All FMECA Project
4 - Defining the System Hierarchy
INTRODUCTION
There is no template defining the specific roles and
responsibilities for carrying out the FMECA tasks;
However It is usually a good practice to make the design
engineer responsible for accomplishing Design FMECAs
PREPARATION
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
It is useful for companies to document the various FMECA roles
and responsibilities in related job descriptions and work
instructions.
Make the Scope Visible
Make the Scope Visible
Assemble the Correct Team
Assemble the Correct Team
Ground Rules and Assumption
Ground Rules and Assumption
Role of Suppliers
Role of Suppliers
Gather and Review Relevant
Information
Gather and Review Relevant
Information
FMECA
PROCEDURE
FMECA
PROCEDURE
7"
All product designs, machinery, and equipment of any kind have a
system hierarchy. It is important for the FMECA practitioner to
understand the system hierarchy.
System definition always includes the interfaces between the
subsystems.
Further definitions relating to system hierarchy follow:
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Scope of the Analysis
FILLING
WHORKSHEET
RISK ANALYSIS
4"
Tasks done Once For All FMECA Project
3 - Identifying Roles and Responsibilities
Roles and Responsibilities
Preparation Tasks For Each
New FMECA Project
The criteria for the occurrence scale must be reviewed and agreed
upon, clearly differentiating the full range of anticipated failure
rates, from very low to very high, and where possible identifying
ranges of failure frequency for each occurrence level that makes
sense for the system or product being analyzed.
PREPARATION
INTRODUCTION
PREPARATION
• 
Tasks done Once For All FMECA Project
2 - Selecting or Modifying FMECA Worksheets and Scales
Assemble the Correct Team
Ground Rules and Assumption
The criteria for the severity scale must be reviewed and agreed
upon, clearly showing needed differentiation between safety and
regulatory risk, loss or degradation of primary and secondary
functions, and lower severity such as annoyance.
Ground Rules and Assumption
INTRODUCTION
Worksheet and Scales
• 
Make the Scope Visible
FMECA
PROCEDURE
Roles and Responsibilities
At this point the FMECA team should agree on the standards to be
followed. If the FMECA standard is not mandated, Automotive Industry
Action Group (AIAG) Fourth Edition (2008) or Society of Automotive
Engineers (SAE) J1739 (2009) provide a good starting point, with a
useful description of the procedure, the worksheet columns, and risk
ranking scales.
However, it is important to tailor the worksheet columns and risk
ranking scales to company-specific applications.
Assemble the Correct Team
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
!
PREPARATION
Gather and Review Relevant
Information
Task done once for all
FMECA projects
2"
PREPARATION
Gather and Review Relevant
Information
PREPARATION
FMECA software selection
Selecting or modifying FMECA scales and columns
Identifying roles and responsibilities
FMECA team training
Legal guidelines for doing FMECAs
Meeting logistics
Defining the system hierarchy (for System and Design
FMECAs)
8.  Access to failure information
Tasks done Once For All FMECA Project
1 - FMECA Software Selection
INTRODUCTION
Task done once for all
FMECA projects
1. 
2. 
3. 
4. 
5. 
6. 
7. 
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
PREPARATION
The following tasks need to be done once for the entire FMECA
project. Note that all of them are not mandatory, the team can decide
which tasks to perform based on the degree of complexity and the
resources allocated to the preparation of FMECA.
The advice is to follow as possible prior actions to implement a robust
FMECA.
FILLING
WHORKSHEET
RISK ANALYSIS
Hierarchy: A partitioning scheme that establishes an ordered
relationship between the
items in a system, where the items are
represented as being “above,” “below,” or “at the same level as” one
another.
Subsystem: A system in and of itself (refer to the system definition)
contained within
a higher level system. The functionality of a
subsystem contributes to the overall functionality of the higher level
system. The scope of a subsystem’s functionality is less than the scope
of functionality contained in the higher level system. Subsystem
definition always includes the interfaces between the components.
8"
87!
INTRODUCTION
PREPARATION
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
PREPARATION
PREPARATION
Tasks done Once For All FMECA Project
4 - Defining the System Hierarchy
Tasks done Once For All FMECA Project
5 - Access to Failure Information
Component: Composed of multiple parts; a clearly identified subset
of the product being designed or produced.
Part: One, two, or more pieces joined together to make a component;
these pieces comprise the lowest level of separately identifiable items
within a system and are not normally subject to disassembly without
destruction or
impairment of its designed use.
Task done once for all
FMECA projects
When performing a Design FMECA,
a portion of the system configuration
could look like this, with as many
subsystems and components as
needed:
•  System
Subsystem A
Component A.1
Component A.2
Subsystem B
Component B.1
Component B.2
Worksheet and Scales
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Task done once for all
FMECA projects
Software Selection
System Hierarchy
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
9"
FILLING
WHORKSHEET
RISK ANALYSIS
PREPARATION
INTRODUCTION
Once the one-time tasks are completed, including defining the
system hierarchy, the following are the primary preparation tasks
that should be done for each new FMECA project:
PREPARATION
Task done once for all
FMECA projects
Software Selection
1.  Determine the scope of the analysis
2.  Make the scope visible
•  FMECA Block Diagram
•  Parameter Diagram (P-Diagram)
•  FMECA Interface Matrix
•  Functional Block Diagram
3.  Assemble the correct team
4.  Establish the ground rules and assumptions
5.  Establish the role of suppliers
6.  Gather and review relevant information
•  “Gather Information Checklist”
7.  Prepare FMECA software for first team meeting (if used)
8.  Ready for first-meeting checklist
11"
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
PREPARATION
INTRODUCTION
PREPARATION
Task done once for all
FMECA projects
Software Selection
Software Selection
Worksheet and Scales
Worksheet and Scales
Roles and Responsibilities
Roles and Responsibilities
Design'
FMECA'
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Make the Scope Visible
Assemble the Correct Team
Assemble the Correct Team
Ground Rules and Assumption
Ground Rules and Assumption
Role of Suppliers
Role of Suppliers
Gather and Review Relevant
Information
Gather and Review Relevant
Information
FMECA
PROCEDURE
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
13#
System Hierarchy
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
!
Determining the scope of the analysis is an extremely important step
because clearly defined boundaries establish the issues that are to be
considered and the approach that the team will take during the
analysis. For example, the scope could be identified thus:
•  A high-level analysis focusing generally on the entire system or
process, including interfaces and integration
•  A detailed analysis focusing intensively on a specific aspect of
the system or process
FILLING
WHORKSHEET
RISK ANALYSIS
14#
PREPARATION
PREPARATION
Preparation Tasks For Each New FMECA Project
1 – Determine the Scope of the Analysis
Preparation Tasks For Each New FMECA Project
2 – Make the scope visible
INTRODUCTION
In defining the scope of any FMECA project, it is essential to include
the interfaces between adjacent subsystems or components. This is
important because empirical data show that at least 50% of problems
occur at the interfaces between sub- systems or components
Roles and Responsibilities
Failure Information
The next step in narrowing down the project focus is determining
the specific boundaries or scope of the individual FMECA.
FMECA
PROCEDURE
Figure: Design FMECA information flow
INTRODUCTION
PREPARATION
12#
Preparation Tasks For Each New FMECA Project
1 – Determine the Scope of the Analysis
Task done once for all
FMECA projects
FILLING
WHORKSHEET
RISK ANALYSIS
Figure: graphical depiction of the FMECA “road map.” The left portion shows
the preparation steps.
FILLING
WHORKSHEET
RISK ANALYSIS
PREPARATION
Failure Information
3.  General Lists of Failure Modes, Causes, and Failure Mechanisms.
There are publications of generic failure modes, causes, and failure
10#
mechanisms that can be helpful to FMECA teams.
Preparation Tasks For Each New FMECA Project
INTRODUCTION
Scope of the Analysis
2.  FMECA “Phrase Libraries”: (A “phrase library” is a list of
predefined descriptions that can be used to define any of the textbased record properties in an FMECA.) FMECA teams should have
easy access to all past functions, failure modes, effects, causes,
controls, and recommended actions from all previous FMECAs.
Good relational database software supports this feature.
PREPARATION
PREPARATION
Preparation Tasks For Each
New FMECA Project
1.  Past FMECAs: FMECA teams should have easy access to all past
company- generated FMECAs, organized by type or description, so
that teams can find past FMECAs that are similar to current
FMECA projects.
Preparation Tasks For Each New FMECA Project
Preparation Tasks For Each New FMECA Project
System Hierarchy
FMECA teams need easy access to information that supports
identification of failure modes and causes.
The following are general sources of information about failure modes
and causes that may be useful to FMECA teams.
Worksheet and Scales
Roles and Responsibilities
Preparation Tasks For Each
New FMECA Project
Software Selection
Roles and Responsibilities
PREPARATION
Failure Information
INTRODUCTION
PREPARATION
INTRODUCTION
PREPARATION
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
For Design FMECAs, the scope typically includes design-related
deficiencies, with emphasis on improving the design and ensuring
product operation is safe and reliable during the useful life of the
item.
For Machinery FMECAs, the scope includes the subsystem itself, as
well as the interfaces between adjacent components.
System Hierarchy
•  A Block Diagram (or boundary diagram) is a visual depiction of the
entire system or design to show clearly the boundaries of the
FMECA analysis (what is included and not included), the interfaces
between the items, and other information that can help to depict the
scope of the FMECA.
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Role of Suppliers
Gather and Review Relevant
Information
Gather and Review Relevant
Information
FMECA
PROCEDURE
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
FILLING
WHORKSHEET
RISK ANALYSIS
15#
FMECA Block Diagram
•  Specifically, the FMECA Block Diagram is a diagram showing the
physical and logical relationships between the components in the
system or assembly and the boundary of the analysis. It identifies
relationships and dependencies between components, such as
physical connection, material exchange, energy transfer, and data
exchange, and usually shows the inputs and outputs
•  There should be enough detail in the diagram to visually define the
scope of the analysis so the team can maintain the proper scope and
not inadvertently expand the project.
16#
88!
INTRODUCTION
PREPARATION
PREPARATION
PREPARATION
Preparation Tasks For Each New FMECA Project
2 – Make the scope visible
Preparation Tasks For Each New FMECA Project
2 – Make the scope visible
INTRODUCTION
FMECA Block Diagram Examples
PREPARATION
Task done once for all
FMECA projects
Software Selection
Software Selection
Worksheet and Scales
Worksheet and Scales
Roles and Responsibilities
Roles and Responsibilities
System Hierarchy
System Hierarchy
Failure Information
Failure Information
Preparation Tasks For Each
New FMECA Project
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Scope of the Analysis
Make the Scope Visible
Make the Scope Visible
Assemble the Correct Team
Assemble the Correct Team
Ground Rules and Assumption
Ground Rules and Assumption
Role of Suppliers
Role of Suppliers
Gather and Review Relevant
Information
Gather and Review Relevant
Information
FMECA
PROCEDURE
Example of FMECA block (boundary) diagram for portion of flip glass–lift gate subsystem
FILLING
WHORKSHEET
RISK ANALYSIS
INTRODUCTION
PREPARATION
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
17#
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Ground Rules and Assumption
Role of Suppliers
PREPARATION
INTRODUCTION
FMECA Interface Matrix
PREPARATION
•  FMECA interface matrix is a chart with the subsystems and/or
components (depending on the scope of the FMECA) on both the
vertical and horizontal axes. The chart shows which interfaces must
be considered in the analysis and the type of interface.
System Hierarchy
•  An interface is the point or surface where two parts or subsystems
meet, and it can take various forms. There are four primary types of
interfaces:
•  physical connection
•  material exchange
•  energy transfer
•  data exchange.
•  Interface Matrix is supplemental to the FMECA Block Diagram
and is done when the FMECA team wants to ensure that all of the
various types of interfaces are included in the analysis, missing
none.
19#
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
20#
PREPARATION
INTRODUCTION
Functional Block Diagram
PREPARATION
•  A Functional Block Diagram is a visual tool to describe the
operation, interrelationships, and interdependencies of the
functions of a system or equipment.
•  By making the primary functions of the equipment visible, it
allows the FMECA team members to agree on how the system
works and identify the beginning and end of system or equipment
operation.
Functional Block Diagram
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
•  Each primary (high-level) function is placed in a “block” and
visually laid out in the sequence performed. Inputs and outputs
are added for clarity.
21#
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
FILLING
WHORKSHEET
RISK ANALYSIS
Example of a Functional Block Diagram for a flashlight operation
22"
PREPARATION
PREPARATION
Preparation Tasks For Each New FMECA Project
3 – Assemble the Correct Team
Preparation Tasks For Each New FMECA Project
3 – Assemble the Correct Team
INTRODUCTION
One of the most important steps in preparing an FMECA is selecting
the right team because FMECA is a cross-functional team activity.!
"
There are three primary reasons for the necessity to have the correct
team when doing an FMECA:"
"
1.  People have “blind spot”. A well-defined cross functional
team minimize the errors inherent with “blind spots”."
2.  The FMECA analysis requires subject-matter experts from a
variety of disciplines to ensure incorporation of all necessary
inputs into the exercise."
3.  One of the indispensable values of an FMECA is the cross
talk and synergy between subject-matter experts that occur
during the meetings. Well-defined groups can discover things
that individuals often miss."
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
FMECA interface matrix example: Hand Brake Subsystem
Preparation Tasks For Each New FMECA Project
2 – Make the scope visible
INTRODUCTION
Worksheet and Scales
Interface type:
•  Physical (P)
•  Material Exchange
(M)
•  Energy Transfer (E)
•  Data Exchange (D)
PREPARATION
FMECA
PROCEDURE
Roles and Responsibilities
Interfaces can
contain up to 50% or
more of the total
failure modes
Preparation Tasks For Each New FMECA Project
2 – Make the scope visible
FILLING
WHORKSHEET
RISK ANALYSIS
!
Software Selection
Worksheet and Scales
Gather and Review Relevant
Information
Software Selection
FMECA Interface Matrix Example
Roles and Responsibilities
FMECA
PROCEDURE
Task done once for all
FMECA projects
18#
Task done once for all
FMECA projects
Gather and Review Relevant
Information
PREPARATION
FMECA block diagram example: hand brake subsystem.
Preparation Tasks For Each New FMECA Project
2 – Make the scope visible
Make the Scope Visible
Assemble the Correct Team
FILLING
WHORKSHEET
RISK ANALYSIS
PREPARATION
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Preparation Tasks For Each New FMECA Project
2 – Make the scope visible
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
FMECA Block Diagram Examples
Task done once for all
FMECA projects
PREPARATION
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
•  Large systems or subsystems may require more than one design
representative
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
•  Supplier partners may be included for critical parts on a need-toknow basis.
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
•  In addiction, the FMECA core team can invite other experts for
specific topics during FMECA meeting
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
23#
•  A typical core team for a Design FMECA might include
representatives from system engineering, design engineering, plant
assembly, product engineering, supplier quality, maintenance etc.
FILLING
WHORKSHEET
RISK ANALYSIS
•  The whole idea is to get the right people in the room to be able to
analyze the entire design, come to agreement on root causes, and
agree on solutions for high-risk issues.
24#
89!
PREPARATION
PREPARATION
Preparation Tasks For Each New FMECA Project
3 – Assemble the Correct Team
Preparation Tasks For Each New FMECA Project
3 – Assemble the Correct Team
INTRODUCTION
PREPARATION
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
INTRODUCTION
The following are suggestion, based on application experience, for
selecting the right FMECA team:!
!
1.  Each of the FMECA team members should be a subject-matter
expert in his/her discipline, not a “stand-in” to attend the
meeting.!
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Gather and Review Relevant
Information
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
2.  It is a good idea to have between three and six team members.!
3.  FMECA team members need to be trained on FMECA
procedure and facilitated by someone who is trained in
facilitation techniques.!
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
5.  There can be more than one design engineer to cover different
aspects of the design.!
25#
Worksheet and Scales
Roles and Responsibilities
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Role of Suppliers
Gather and Review Relevant
Information
PREPARATION
PREPARATION
Preparation Tasks For Each New FMECA Project
4 – Establish the Ground Rules and Assumptions
INTRODUCTION
Before beginning the analysis, the team should discuss (and
document) the underlying assumptions of the analysis and specific
ground rules for how it will be performed.
•  A Design FMECA focuses on design-related issues emphasizing
how the design can be improved to ensure that product-related risk
is low during the useful life of the equipment. This includes any
potential failure modes and causes that can occur during the
manufacturing or assembly process, which are the result of the
design.
PREPARATION
Task done once for all
FMECA projects
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
•  A Design FMECA usually assumes the product will be
manufactured within engineering specifications.
Assemble the Correct Team
Ground Rules and Assumption
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
27#
FILLING
WHORKSHEET
RISK ANALYSIS
System Hierarchy
PREPARATION
Preparation Tasks For Each New FMECA Project
6 – Gather and Review Relevant Information
INTRODUCTION
Part of the preparation for an FMECA project includes determining
the role of suppliers. Root causes of important system or subsystem
failure modes can have their source within supplier parts.
Therefore, the FMECA team must consider how to involve the
supplier for critical components in the Design FMECA and this may
involve different approaches:
•  Invite the supplier to the FMECA team meeting when reviewing a
subsystem that includes a supplier part.
•  Conduct an FMECA jointly with a supplier or suppliers of critical
parts.
Role of Suppliers
•  A third approach is for a representative from the OEM to review
and approve the supplier FMECA for critical parts.
!
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Make the Scope Visible
Assemble the Correct Team
29#
One of the most important steps in FMECA preparation is gathering all of
the relevant documents and information. If this step is missed or done
inadequately the FMECA meetings will be burdened with extra tasks
related to missing information.
In general, the following information is important to have available to the
FMECA team:
•  System Hierarchy: As discussed previously is a key part of FMECA
preparation and documentation.
•  Past FMECAs: All past FMECAs for similar systems or designs or
assemblies should be available to the FMECA team. A relational
database best accomplishes this so that the FMECA information is easily
accessible to the FMECA team.
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Task done once for all
FMECA projects
Ground Rules and Assumption
Ground Rules and Assumption
Gather and Review Relevant
Information
PREPARATION
Scope of the Analysis
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
28#
PREPARATION
5 – Establish the Role of Suppliers
Failure Information
1.  Does the FMECA team assume the product will be manufactured or
assembled within engineering specifications?
2.  Does the FMECA team wish to consider an exception, such as the
part design may include a deficiency that could cause unacceptable
variation in the manufacturing or assembly process?
3.  What are the assumed environmental conditions?
4.  What are the assumed operating profiles?
5.  Will the FMECA team assume product abuse by the user? If so, to
what levels?
6.  What is the definition of failure used in the FMECA?
7.  How will the FMECA team use severity rankings and RPNs to
prioritize issues for corrective actions?
8.  What is the process by which the FMECA team obtains approval
for FMECA recommended actions and follow-up for execution?
Preparation Tasks For Each New FMECA Project
INTRODUCTION
Preparation Tasks For Each
New FMECA Project
The following is an example of some of the ground rules and
assumptions the FMECA team may consider before commencing the
FMECA project:
Software Selection
Worksheet and Scales
Roles and Responsibilities
Role of Suppliers
Roles and Responsibilities
26#
4 – Establish the Ground Rules and Assumptions
Gather and Review Relevant
Information
Software Selection
9.  A supplier representative may participate in an original
equipment manufacturer (OEM) Design FMECA, usually on an
ad hoc basis to provide supplier –related input.!
FILLING
WHORKSHEET
RISK ANALYSIS
FMECA
PROCEDURE
Worksheet and Scales
8.  It is also a good idea to have team members who either have
decision-making authority or can provide access to people with
decision-making authority.!
FMECA
PROCEDURE
Role of Suppliers
Task done once for all
FMECA projects
7.  It is a good idea to have individuals on the FMECA team that
will be involved with the implementation of recommended
changes.!
Assemble the Correct Team
Gather and Review Relevant
Information
PREPARATION
6.  Management often has to be involved in empowering FMECA
teams to ensure attendance and support.!
Preparation Tasks For Each New FMECA Project
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Software Selection
Ground Rules and Assumption
4.  Ad hoc team members may be enlisted as needed to cover
selected issues.!
INTRODUCTION
PREPARATION
Task done once for all
FMECA projects
System Hierarchy
Ground Rules and Assumption
Role of Suppliers
PREPARATION
FILLING
WHORKSHEET
RISK ANALYSIS
•  Field History: One of the keys to successful FMECAs is using them to
avoid repeating past failures. Every company experiences some field
failures. The most successful companies do not repeat them. The
FMECA team needs to ensure that a summarized list of field failures for
similar products is easily available during the FMECA project.
30#
90!
1.3 D-FMECA Procedure
Design-FMECA Methodology
FMECA PROCEDURE
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
Sequence of Steps
Sequence of Steps
Items
Items
Functions
Functions
Failure Modes
Failure Modes
Effects
Effects
Severity Ranking
Cause and Failure
Mechanisms
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Occurrence Ranking
Controls
Controls
Detection Ranking
Detection Ranking
Risk Priority Number
Risk Priority Number
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
FILLING
WHORKSHEET
1"
RISK ANALYSIS
RISK ANALYSIS
Figure: graphical depiction of the FMECA “road map.” The left portion
shows the preparation steps.
FMECA PROCEDURE
FMECA PROCEDURE
Sequence of Steps
Sequence of Steps
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
INTRODUCTION
Once the FMECA team meetings have begun, there are many ways to
proceed in doing the FMECA analysis.
There is no standard method for the sequence of steps; however, many
experienced FMECA teams use the following strategy:
1.  Enter all the primary functions for the item under analysis.
2.  Beginning with the first function, enter all the failure modes and
corresponding effects, with severity rankings for the most serious effect
of each failure mode.
3.  For each failure mode, enter all of the causes, with occurrence rankings
for each cause.
4.  For each cause, enter prevention-type controls and detection-type
controls, with detection rankings for the best detection-type control.
5.  Enter the next function and continue until all the functions are analyzed
through Risk Priority Numbers (RPNs).
6.  Review the high severities and high RPNs, and develop all needed
recommended actions that will reduce risk to an acceptable level.
7.  Review high-risk FMECA issues, and corresponding recommended
actions, with management and proceed to execution steps.
3"
RISK ANALYSIS
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
•  Each step of the FMECA analysis should be done with enough
clarity and detail to proceed to the next step in the analysis. As the
team proceeds, each step, carefully and properly articulated, makes
the subsequent step easier for the team to define.
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
•  There is a one-to-many relationship between each of these steps.
For example, for one item, there may be many functions. For one
function, there may be many failure modes. For one failure mode,
there may be many causes. For one cause, there may be many
controls. In addition, for one cause, there may be many
recommended actions.
•  It is important to understand the logical relationship between the
various elements of FMECA. (See figure in the next page)
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
4"
RISK ANALYSIS
FMECA PROCEDURE
FMECA PROCEDURE
Sequence of Steps
Items
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
Sequence of Steps
Sequence of Steps
Items
Items
The FMECA team identifies or confirms the item to be analyzed with
FMECA procedure. This will be the specific portion of the system hierarchy
established during the Preliminary Risk Assessment, or otherwise
determined by the FMECA team.
Effects
Effects
The FMECA team will need to decide how to address interfaces. From the
FMECA Block Diagram and the FMECA interface matrix, all of the
interfaces that are within the scope of the FMECA project should be clearly
identified.
Severity Ranking
Cause and Failure
Mechanisms
Severity Ranking
Cause and Failure
Mechanisms
There are two ways that the FMECA team can ensure that all the interfaces
are properly addressed:
Occurrence Ranking
Occurrence Ranking
Functions
Functions
Failure Modes
Failure Modes
Controls
Controls
Detection Ranking
Detection Ranking
Risk Priority Number
Risk Priority Number
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
FILLING
WHORKSHEET
5"
RISK ANALYSIS
•  The first option is to add the interfaces to the system hierarchy directly
underneath the system (for subsystem interfaces) or directly below the
subsystem (for component interfaces).
•  The second (and preferred) option is to keep the system hierarchy as it is
traditionally defined, but include each interface as a separate function,
properly describing the function of the interface.
6"
RISK ANALYSIS
FMECA PROCEDURE
FMECA PROCEDURE
Functions
Functions
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Items
INTRODUCTION
For each item under consideration, the FMECA team identifies the
primary functions.
A function is “what the item or process is intended to do, usually to a
given standard of performance or requirement”.
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
PREPARATION
FMECA
PROCEDURE
Care should be taken to only include what the team believes to be the
primary functions, and not include requirements that are too detailed
and outside the objectives of the FMECA.
Thought-Starter Questions
When identifying functions the team can be asked questions such as:
Sequence of Steps
Items
Functions
It is a good practice to avoid long lists of functions with narrow
differences, as it adds complexity to the analysis without adding value.
It is helpful to list functions separately when they are significantly
different.
Risk Priority Number
!
2"
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
• 
• 
• 
• 
• 
• 
“What are the primary purposes of this item?”
“What is the item supposed to do? What must the item not do?”
“What is the standard of performance?”
“What functions occur at the interfaces?”
“What safety-related functions are important for this item?”
“Any other questions that ensure all of the primary functions are
determined
Controls
Detection Ranking
Risk Priority Number
For Design and Machinery FMECAs, the FMECA Block Diagram and
Functional Block Diagram (if done) are both input to establishing the
functions, and make this step considerably easier.
7"
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
8"
91!
FMECA PROCEDURE
FMECA PROCEDURE
Functions
Functions
INTRODUCTION
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Requirements
PREPARATION
Remember, for Design FMECAs, the function needs to include the
standard of performance or requirements.
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
Sequence of Steps
Items
Items
Functions
FMECA
PROCEDURE
Requirements are measurable characteristics of a product function or
its operation. A separate column may be included in the FMECA
worksheet for requirements or they can be included in the function
description. Functions may have multiple requirements.
In many situations, an existing document may contain detailed
information about the functions that the item or step is intended to
perform.
•  Quality Function Deployment (QFD) contains design requirements
that should be considered in the Design FMECA.
•  Technical Specifications contain product requirements that describe
the performance objectives and functions of product designs.
(See also checklist of function type)
9"
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
Examples of subsystem-level and component-level function from allterrain Hand Brake Design FMECA.
FILLING
WHORKSHEET
10#
RISK ANALYSIS
FMECA PROCEDURE
FMECA PROCEDURE
Failure Modes
Failure Modes
INTRODUCTION
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
For each primary function, the FMECA team identifies the potential failure
modes.
Failure mode is defined as “the manner in which the item or operation
potentially fails to meet or deliver the intended function and associated
requirements.”
Functions
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Each potential failure mode in an FMECA is considered independently of
any other failure mode. This enables the team to address the unique
reasons (causes of failure) for each given failure mode.
In the case of failure modes (or causes) that are not independent (in other
words, they occur in a dependent relationship) consider using Fault Tree
Analysis (FTA) to model the dependency. (More about FTA in tools
section)
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
Remember, the failure mode is not merely the antithesis of the function.
Rather, it is the manner in which an item or operation potentially fails to
meet or deliver the intended function and associated requirements.
Avoid failure mode wording that is too general such as “doesn’t work. Be
specific.
11"
RISK ANALYSIS
Failure Conditions
The use of failure conditions can help identify unique failure modes.
Sequence of Steps
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Controls
Detection Ranking
FMECA
PROCEDURE
Items
Items
Failure Modes
PREPARATION
Detection Ranking
Risk Priority Number
Examples of failure conditions include:
•  Premature operation
•  Failure to operate at a prescribed time (complete loss of function)
•  Intermittent operation
•  Failure to cease operation at a prescribed time
•  Loss of output during operation (reduced performance)
•  Degraded operation (loss of performance over time)
•  Performing an unintended or undesired function
Each function examined in relation to these failure conditions ensures
identification of all relevant failure modes.
FMECA Linkages
FILLING
WHORKSHEET
12#
RISK ANALYSIS
FMECA PROCEDURE
FMECA PROCEDURE
Failure Modes
Failure Modes
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
INTRODUCTION
Controlling the Failure Mode Description
PREPARATION
•  The verbiage of individual failure modes can be cataloged and
controlled for usage by other FMECA teams.
Items
Functions
Failure Modes
FMECA
PROCEDURE
Sequence of Steps
Items
•  This enables analysis and dissemination of failure information
between project teams and the entire organization.
Effects
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
•  Some companies ascribe a failure mode ID number to each unique
failure mode.
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
•  This allows companies to analyze common failure modes across
FMECAs and the entire company to develop broad strategies for
risk reduction.
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
Controls
Detection Ranking
FMECA Linkages
FILLING
WHORKSHEET
FILLING
WHORKSHEET
13#
RISK ANALYSIS
RISK ANALYSIS
INTRODUCTION
INTRODUCTION
Items
Functions
•  For each of the failure modes, the team lists the effects.
PREPARATION
•  An effect is “the consequence of the failure on the system or end
user. For Process FMECAs, the team should consider the effect of
the failure at the manufacturing or assembly level, as well as at the
system or end user.”
Effects
Occurrence Ranking
Controls
•  Depending on the FMECA standard used, this may include local,
next level, and end effect, or it may include only the end effect.
•  Avoid wording effects too generally, such as “customer
dissatisfaction.” Be specific and describe the effect or consequence
on the end user.
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
!
•  The verbiage of individual effects can be cataloged and controlled
for usage by other FMECA teams. This enables analysis and
dissemination of end effects across project teams and the entire
organization.
15#
Thought-Starter Questions
When identifying effects the team can be asked questions such as:
Sequence of Steps
Items
Functions
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Detection Ranking
Risk Priority Number
FMECA
PROCEDURE
Failure Modes
Failure Modes
Severity Ranking
Cause and Failure
Mechanisms
14#
Effects
Effects
Sequence of Steps
Example of subsystem-level
failure mode from all-terrain
Hand Brake Design FMECA.
FMECA PROCEDURE
FMECA PROCEDURE
FMECA
PROCEDURE
When identifying failure modes the team can be asked questions, such as:
•  “In what way could the item fail to perform its intended function?”
•  “In what way could the item perform an unintended function?”
•  “What could go wrong with this item?”
•  “What could go wrong at the interfaces?”
•  “What has gone wrong with this item in
the past?”
•  “How could the item
be abused or
misused?”
•  “What concerns do
you have with this
design?”
Risk Priority Number
FMECA Linkages
PREPARATION
Though-Starter Questions
•  “What is the consequence of the failure?”
•  “If the item fails, what will be the consequences at the local level?
At the next higher level? At the system level? At the end user?”
•  “If the item fails, what will the customer see, feel, or experience?”
•  “Will the failure cause potential harm to the end users?”
•  “Will the failure cause potential violation of regulations?”
•  “What would a failure mean to adjacent parts/subsystems?”
•  Any other questions that ensure the effects of failure are fully
understood at the local level, the next level, and system and/or end
user.
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
16#
92!
FMECA PROCEDURE
FMECA PROCEDURE
Effects
Severity Ranking
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
Sequence of Steps
Sequence of Steps
Items
Items
Functions
Functions
Failure Modes
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Effects
Severity Ranking
Cause and Failure
Mechanisms
Example(of(component0level(effect(
from(all0terrain(Brake(Cable(
Machinery(FMECA!
Occurrence Ranking
Controls
Controls
Detection Ranking
Detection Ranking
Risk Priority Number
Risk Priority Number
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
Example(of(subsystem0level(effect(
from(all0terrain(Hand(Brake(Design(
FMECA!
FMECA PROCEDURE
Causes and Failure mechanisms
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Sequence of Steps
Items
Items
Functions
Functions
Failure Modes
Failure Modes
Effects
Effects
Severity Ranking
Cause and Failure
Mechanisms
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Occurrence Ranking
Controls
Controls
Detection Ranking
Detection Ranking
Risk Priority Number
Risk Priority Number
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
FILLING
WHORKSHEET
Example(of(severity(ranking(
RISK ANALYSIS
19#
Effects
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Functions
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
!
•  In Design FMECAs, root causes are often described in terms of
product characteristics, such as:
•  dimensions
•  weight
•  orientation
•  Hardness
•  strength
20#
RISK ANALYSIS
FMECA PROCEDURE
INTRODUCTION
Cause Categories
PREPARATION
If needed, the FMECA team can develop and refer to cause
categories as “thought triggers” to help the team brainstorm specific
causes to be sure no important causes are missed.
FMECA
PROCEDURE
Sequence of Steps
Items
Controlling the Cause Description
The verbiage of individual causes can be cataloged and controlled for
usage by other FMECA teams. This enables analysis and
dissemination of common causes across project teams and the entire
organization.
Functions
Design-related cause categories include:
•  system interactions
•  time based
•  operating environment
•  customer usage
•  functional performance
•  design-for-manufacturing or assembly.
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Cause categories are only informational, and can be tailored to
individual applications. The actual cause will need to be expanded to
ensure root cause is identified and described adequately.
21#
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
Dependent Causes
It is possible for a failure mode to result only when two or more
causes occur simultaneously, or in other words, are dependent on one
another. FMECAs typically assume that causes are independent.
There are two alternatives when the FMECA team needs to address
dependent causes.
•  The first is to shift to FTA to model the dependent relationships
between causes and other events. (See more in tools section)
•  The second alternative is to list the causes together in one entry in
the FMECA worksheet, using the word “and” in between the
causes.
22"
RISK ANALYSIS
FMECA PROCEDURE
FMECA PROCEDURE
Causes and Failure mechanisms
Causes and Failure mechanisms
INTRODUCTION
Failure Mechanisms
A failure mechanism is the actual physical phenomenon behind the failure
mode or the process of degradation or chain of events leading to and resulting
in a particular failure mode. The mechanism should be listed as concisely and
completely as possible.
Items
Failure Modes
•  There can be one or more causes, and the team should identify as
many causes as are needed to document their concerns. Causes
should be described in sufficient detail to establish the underlying
mechanisms of the cause, often called the “root” cause.
Causes and Failure mechanisms
RISK ANALYSIS
INTRODUCTION
•  A cause is “the specific reason for the failure, preferably found by
asking ‘why’ until the root cause is deter- mined. For Design
FMECAs, the cause is the design deficiency that results in the
failure mode”.
FMECA PROCEDURE
Functions
Severity Ranking
Cause and Failure
Mechanisms
For each failure mode, the FMECA team identifies the causes.
Causes and Failure mechanisms
INTRODUCTION
Items
18#
Severity Ranking
FMECA
PROCEDURE
Failure Modes
Properly assessed severity ranking will help ensure that high severity
and high RPN issues are addressed with corrective actions.
FMECA PROCEDURE
INTRODUCTION
Sequence of Steps
Using the agreed-upon severity scale, the team carefully reviews the
criteria column to make this judgment. If the effect is well defined, the
severity is easily established by reviewing the severity scale criteria.
RISK ANALYSIS
PREPARATION
FMECA
PROCEDURE
Severity is “a ranking number associated with the most serious effect
for a given failure mode, based on the criteria from a severity scale. It
is a relative ranking within the scope of the specific FMECA and is
determined without regard to the likelihood of occurrence or
detection.”
FILLING
WHORKSHEET
17!
INTRODUCTION
PREPARATION
Having identified the most serious effect for the failure mode, the
FMECA team assesses the severity ranking. This is the severity of the
effect of the failure mode, not the severity of the failure mode itself.
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Items
For Design and Machinery FMECAs at the component level, causes can be
further defined and developed by understanding the underlying failure
mechanisms. Causes are the circumstances that induce or activate a failure
mechanism.
Wherever possible, for high-risk issues the FMECA team should define the
cause at the failure mechanism level.
Examples of failure mechanism categories include:
•  Failure mechanism categories relating to metal structure components:
corrosion, cracking, deformation, fatigue, fracture, friction, yielding and
wear.
•  Failure mechanism categories relating to electrical components: dielectric
breakdown, electro-migration, induced current and voltage drop.
•  Failure mechanism categories relating to elastomers: abrasive wear,
compression set, extrusion, hardening, shrinking and swelling.
23#
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Thought-Starter Questions
When identifying causes the team can be asked questions such as:
• 
• 
• 
• 
• 
• 
Occurrence Ranking
Controls
• 
Detection Ranking
Risk Priority Number
FMECA Linkages
• 
“How can the failure occur?”
“What could cause the item to fail in this manner?”
“What circumstances could cause the item to fail to perform
its intended function?”
“Why could the failure occur?”
“What is the mechanism of failure?”
“Are there possible system interactions, degradations,
operating environments,
customer usages, or design-for-manufacturing/assembly
issues that could cause the failure?”
For each cause identified, ask further “whys” in the direction
of isolating root cause.
FILLING
WHORKSHEET
RISK ANALYSIS
24#
93!
FMECA PROCEDURE
FMECA PROCEDURE
Causes and Failure mechanisms
Causes and Failure mechanisms
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
Sequence of Steps
Sequence of Steps
Items
Items
Functions
Functions
Failure Modes
Failure Modes
Effects
Effects
Severity Ranking
Cause and Failure
Mechanisms
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Occurrence Ranking
Controls
Controls
Detection Ranking
Detection Ranking
Risk Priority Number
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
FMECA Linkages
Example of failure modes with associated failure mechanisms and causes.
FILLING
WHORKSHEET
25#
RISK ANALYSIS
RISK ANALYSIS
FMECA PROCEDURE
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
RISK ANALYSIS
The FMECA team
should always ask “why”
to each cause until it is
satisfied the root cause
has been deter-mined.
(See also Five Whys
Checklist)
26#
Occurrence Ranking
For each cause, the FMECA team assesses the occurrence ranking.
This is the likelihood of occurrence of the cause of the failure mode.
•  “Occurrence is a ranking number associated with the likelihood that
the failure mode and its associated cause will be present in the item
being analyzed within the design life”.
•  Using the agreed-upon occurrence scale, the team carefully reviews
the criteria column to make this judgment. This assessment of
occurrence ranking should be as objective as possible, using past
field history of similar items, previous test results, experience with
similar systems, and other sources of information. The FMECA
team should endeavor to be as objective as possible, using the
criteria from the occurrence scale to help deter- mine the
appropriate rank.
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
Properly worded causes, developed to the failure mechanism level for
high-risk issues, will help to assess occurrence ranking and will help in
the process of developing effective actions to
reduce the risk associated with the
failure mode/cause.
INTRODUCTION
INTRODUCTION
FMECA
PROCEDURE
Failure mechanisms should always be included with the cause entry on
high-risk causes at the component level. It is up to the FMECA team if
they want to include failure mechanisms for other causes, such as at the
subsystem or system levels.
FMECA PROCEDURE
Occurrence Ranking
PREPARATION
Summarize
•  Properly assessed occurrence ranking will help ensure that risk due
to frequency of occurrence is addressed with corrective actions,
along with other high severity and high RPN issues.
27#
FILLING
WHORKSHEET
Example of occurrence ranking
FMECA PROCEDURE
FMECA PROCEDURE
Controls
Controls
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
INTRODUCTION
For each cause, the FMECA team identifies the design controls.
PREPARATION
Controls are “the methods or actions currently planned or already in place
to reduce or eliminate risk. Controls can be the methods to prevent or
detect the cause during product development, or can be actions to detect a
problem during service before it becomes catastrophic.”
Most FMECA standards require two types of controls be identified (i.e.,
prevention and detection).
•  Prevention-type design controls describe how a cause, failure mode, or
effect in the product design is prevented based on current or planned
actions; they are intended to reduce the likelihood that the problem will
occur, and are used as input to the occurrence ranking.
•  Detection-type design controls describe how a failure mode or cause in
the product design is detected, based on current or planned actions,
before the product design is released to production, and are used as
input to the detection ranking. Detection controls are intended to
increase the likelihood that the problem will be detected before it
reaches the end user.
29#
RISK ANALYSIS
FMECA
PROCEDURE
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
!  When identifying detection-type design controls for Machinery or
Design FMECAs, the team can be asked questions such as:
•  What is already in place that could possibly detect the cause?
•  What is not in place yet but is currently planned that could
possibly detect
•  the cause?
•  What tests, analyses, or other analytical or physical tasks are
already in place or currently planned that could detect the cause
before launch?
30#
Detection Ranking
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
Sequence of Steps
Sequence of Steps
Items
Items
Functions
Functions
Failure Modes
Failure Modes
Effects
Effects
Severity Ranking
Cause and Failure
Mechanisms
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Occurrence Ranking
Controls
Controls
Example of subsystem-level design controls from all-terrain Hand Brake Design FMECA.
Risk Priority Number
!
!  When identifying prevention-type design controls for Machinery or
Design FMECAs, the team can be asked questions such as:
•  What is already in place that could possibly prevent the cause?
•  What is not in place yet but is currently planned that could
possibly prevent the cause?
•  What design guidelines, design standards, use of field lessons
learned, or other prevention-type tasks are planned or already in
place that could prevent the cause?
FMECA PROCEDURE
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
FILLING
WHORKSHEET
RISK ANALYSIS
Thought-Starter Questions
RISK ANALYSIS
FMECA PROCEDURE
Detection Ranking
28#
RISK ANALYSIS
31#
RISK ANALYSIS
For each cause, the FMECA team assesses the detection ranking. This is
the likelihood that the current detection-type controls will be able to detect
the cause of the failure mode.
For Design and Machinery FMECAs, detection is the ranking number
corresponding to the likelihood that the current detection-type Design
Controls will detect the failure mode/ cause, typically in a time frame
before the product design is released for production.
Using the agreed-upon detection scale, the team carefully reviews the
criteria column to make this judgment. Although it is possible to analyze
each control separately, this is not necessary in most applications.
A suggested approach is assuming the failure has occurred and then
assessing the capability of the detection-type design or process control to
detect the failure mode or cause. If there is no detection-type control for a
given failure mode/cause, the detection ranking should be set to the
highest level.
32#
94!
FMECA PROCEDURE
FMECA PROCEDURE
Detection Ranking
Detection Ranking
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
Sequence of Steps
Sequence of Steps
Items
Items
Functions
Functions
Failure Modes
Failure Modes
Effects
Effects
Severity Ranking
Cause and Failure
Mechanisms
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Occurrence Ranking
Controls
Controls
Detection Ranking
Detection Ranking
Risk Priority Number
Risk Priority Number
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
FILLING
WHORKSHEET
RISK ANALYSIS
Example of detection ranking.
33"
Limitation to using Detection Ranking
The detection ranking scale is the most controversial of the three risk
ranking scales (severity, occurrence, and detection).
The most common misunderstanding or misapplication of the detection
scale is to confuse or commingle the three types of detection risk:
•  Likelihood of detection by the identified controls—specifically,
what is the likelihood that the current detection-type control will
be able to discover the failure mode or its cause (remote, low,
moderate, high, etc.)?
•  Timing of the opportunity for detection—specifically, what is
the timing of the current detection-type control (prior to design
freeze, post design freeze, in service, etc.)?
•  Type of test used to detect the cause of the problem—what is the
quality of test method used to detect the failure mode or its
cause (degradation test, test to failure, pass/fail test, etc.)?
34#
RISK ANALYSIS
FMECA PROCEDURE
FMECA PROCEDURE
Detection Ranking
Risk Priority Number
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
Sequence of Steps
Sequence of Steps
Items
Items
Functions
Functions
Failure Modes
Failure Modes
Effects
Effects
Severity Ranking
Cause and Failure
Mechanisms
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Occurrence Ranking
Controls
Controls
Detection Ranking
Detection Ranking
Risk Priority Number
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
FMECA Linkages
Example of Design FMECA detection scale (integrating three types of detection risk).
35#
RISK ANALYSIS
FILLING
WHORKSHEET
RPN is “a numerical ranking of the risk of each potential failure mode/
cause, made up of the arithmetic product of the three elements: severity
of the effect, likelihood of occurrence of the cause, and likelihood of
detection of the cause.”
RPN is the product of each of the three rating scales: severity, occurrence
and detection:
RPN= S(severity) x O(occurrence) x D(detection)
RPN is not a perfect measure of risk. It has proven useful to a majority
of practitioners, and others have decided to use alternatives. The entire
purpose of the RPN value is to help the FMECA team prioritize issues
for corrective action within the scope of the specific FMECA project.
In application, it is always necessary to separately review and address all
high severities as well as high RPNs. The reason is that high severity, but
low RPN, has the potential to result in high risk to end users and to the
company.
36#
RISK ANALYSIS
FMECA PROCEDURE
FMECA PROCEDURE
Risk Priority Number
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
Risk Priority Number
INTRODUCTION
Limitation of Using RPN
PREPARATION
There are certain limitations to using RPNs. Here are the primary ones:
1.  Subjectivity of RPN: Since the components of RPN are each subjective
ratings, the RPN value is subjective in nature. It only has application in
helping the FMECA team prioritize issues for corrective action within a
given FMECA, and cannot be used to assess risk across different
FMECAs.
2.  Limitations of Detection: The detection scale is controversial for some
companies and practitioners, and as a result, some have chosen not to
use detection ranking at all.
3.  Holes in the Scale: “Although the RPN is an integer scale, it is not
continuous. Many of the numbers in the range of 1 to 1000 cannot be
formed from the product of S, O, and D. This creates ‘holes’ in the
scale. These holes are the cause of the most serious problems in
interpreting the RPN.”[6] This is true particularly if the FMECA team
expects higher RPNs to represent higher risk in a manner that is
continuous and proportional.
37#
FMECA
PROCEDURE
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Limitation of Using RPN
4.  Duplicate RPN Numbers: All possible products of S, O, and D include
many duplicate numbers. It is difficult to accept that failures whose
severities range from 1 (not noticeable except by the most discerning
customer) to 8 (inoperable with loss of primary function) can be
evaluated as having the same importance.
For example:
RPN1 = (S=1) x (O=8) x (D=8) = 64
RPN2 = (S=8) x (O=4) x (D=2) = 64
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
there is very different risk associated between these two examples.
5.  High Severity by Itself: High severity is high risk, regardless of the
RPN. Therefore, it is always necessary to address high severity in
addition to high RPN.
38#
RISK ANALYSIS
FMECA PROCEDURE
FMECA PROCEDURE
Risk Priority Number
Risk Priority Number
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
PREPARATION
Limitation of Using RPN
6.  RPN Thresholds: It is enticing for management to use thresholds
for RPN values and require defined action if the RPN value
exceeds the given thresh- old. In most cases, this is a flawed
approach, as it can easily become a numbers game. If
management exerts sufficient pressure, through excessive
consequences for RPN values exceeding thresholds, the FMECA
teams or suppliers can bias the RPN components (S, O, and D)
to lower the resulting RPN below the threshold. If RPN
thresholds are used at all, they should only trigger a heightened
level of review, not specifically mandated action.
FMECA
PROCEDURE
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Detection Ranking
Risk Priority Number
Risk Priority Number
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
FILLING
WHORKSHEET
RISK ANALYSIS
!
INTRODUCTION
39#
RISK ANALYSIS
Alternatives to RPN
1.  S x O: The product of S×O gives a numerical rating of the combined
risk of severity and occurrence, sometimes called a Criticality
Number. If the FMECA team chooses to use S×O instead of RPN,
then the team needs to consider how to address the risk associated
with detection.
2.  S-O-D: Some companies use the numerical value of S-O-D. If
severity is 7, occurrence is 3, and detection is 5, then S-O-D is 735.
This avoids the “holes” in RPN, but severity by itself must still be
addressed.
3.  S-O-D Matrix: Another interesting approach is to make a threedimensional chart based on the individual rankings for severity,
occurrence, and detection. Liken this to an xyz chart, with severity on
the x-axis, occurrence on the y-axis, and detection on the z-axis. This
approach takes into account and prioritizes for risk every
combination of S, O, and D.
40#
95!
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
!
FMECA PROCEDURE
FMECA PROCEDURE
FMECA Linkages
FMECA Linkages
Design FMECA Linkage to Design Verification Plan
A Design Verification Plan (DVP) documents the strategy that will be used
to verify and ensure that a product or system meets its design specifications
and other requirements. Each of the product requirements are listed in the
DVP along with the physical test or analytical method that will determine if
the requirement is met.
The linkage between the FMECA and the DVP plan goes two ways:
1.  The FMECA team includes representation from the testing department
in order to ensure that the team considers all needed input from testing
as part of the analysis.
2.  the FMECA team ensures that the DVP is impacted by the results of the
FMECA.
Specifically, when the FMECA team identifies failure modes and associated
causes that are not currently well detected in test plans or procedures, the
test plans and procedures should be updated and improved so all failure
modes of concern are detected during testing. Any changes to test
procedures or test plans should be identified as FMECA recommended
actions.
41#
Example(of(Design(Verifica4on(Plan(for(hand(brake(subsystem.!
42!
96!
1.4 Filling Worksheet D-FMECA
FILLING WORKSHEET
Design-FMECA Methodology
Design-FMECA Template
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
(8)$
(1)$
(4)$
(2)$
(2A)$
(5)$
(6)$
(9)$
(3)$
(7)$
(10)$
Part name
FILLING
WHORKSHEET
RISK ANALYSIS
(11)$
(12)$
(13)$
(14)$
(15)$
(16)$
(17)$
(18)$
(19)$ (20)$
(21)$
(22)$
(23)$
(24)$
1"
2"
FILLING WORKSHEET
FILLING WORKSHEET
Design-FMECA Template
Design-FMECA Template
INTRODUCTION
INTRODUCTION
1)  Subsystem D-FMECA: The focus of the Subsystem D-FMECA is to
ensure that all interfaces and interactions are covered among the
various subsystems that make up the subsystem.
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
2)  Design responsibility: Name the responsible organization, division,
or department that has responsibility for system design.
FILLING
WHORKSHEET
RISK ANALYSIS
(2A) Person responsibility: Sometimes is necessary to name the person
who is responsible for the system design.
RISK ANALYSIS
PREPARATION
FMECA
PROCEDURE
3)  Involvement of others area: Name other people or activities (within
the organization) that affect the design of the system.
6)  Engineering release date: identify the date (Mo/Day/Yr) that the product
is scheduled to be released.
7)  Prepared by: Generally, the name of the design engineer responsible for
FMECA is defined. Sometimes, additional information also is recorded,
such as:
•  Telephone number of the system design engineer
•  Address of the system design engineer
•  Organizational activity (in other words, division, department)
•  Team numbers (name, telephone, address, and so on)
8)  FMECA Number: Enter the M-FMECA document number, which may
be used for tracking.
4)  Involvement of suppliers or others: Identify other people,
suppliers, and/or plants (outside the organization) that affect the
design and are involved in the design, manufacturing or assembly, or
service of the system.
9)  Part name: Identify the part name. Often the latest engineering drawing
number is defined.
10)  FMECA date/rev: Record the date (Mo/Day/Yr) of the initiation of
FMECA and of the latest revision.
5)  Model or product: Name the model and/or the product using
system.
3"
4"
FILLING WORKSHEET
FILLING WORKSHEET
Design-FMECA Template
INTRODUCTION
Design-FMECA Template
(11) Design Function: The engineer writes the design intent, purpose, goal or
objective of the design. The design function must be derived from customer
needs, wants, and expectation.
For the design function to be effective, it must be:
•  Concise
•  Exact
•  Easy to understand
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Project/name:___________________________________________
Scope/key/element(s):____________________________________
Project/restrictions:______________________________________
Drawing/number:________________________________________
Team/number:__________________ Date:___________________
specification
Noun
basic
Verb/
Second
List/of/functions
No.
Product/requirement
How/much?/When?
1
2
3
4
5
6
7
8
!  It can also be identified through a
functional block diagram, which will
show the system elements as functional
blocks into which the system may be
decomposed.
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
!  If a statement is used to describe the
function, should be used specific terms.
The writer of FMECA should try to use
active verbs and appropriate nouns. The
active verbs define performance and
performance define functions. The
combination of the active verb with the
noun define the relationship. !!
5!
6"
FILLING WORKSHEET
FILLING WORKSHEET
Design-FMECA Template
Design-FMECA Template
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
INTRODUCTION
(13) Potential effect(s) of failure: A potential effect of the failure is the
consequence of its failure on the next higher design, system, product, customer,
and/or government regulations.
The questions usually asked are:
•  What does the customer experience as a result of the failure
mode described?
•  What happens or what is/are the ramification(s) of this problem
or failure?
Document one may review to
identify potential effects
Examples of potential effect of failure
Historical data
Next higher system: fails to operate
Warranty documents
Next lower system: none
Field service
Other system(s): none
Feasibility studies
Product: performance degradation
Customer complaints
Customer: complete dissatisfaction; system
fails to operate
Similar current or past FMECAs
Government: may not comply with STD-XXX
Reliability data
7"
!
(12) Potential failure mode: The problem, the concern, the opportunity to
improve, the failure, the defect. When considering the potential failure
mode one must think of the loss of a design function – a specific failure.
For each design function identified in item 11 the corresponding failure of
the function must be listed.
To help identify of the potential failure mode there are 3 methods:
1.  Think the of the negative or loss the function. For example:
•  Fails to open
•  Component shorts
•  Broken
•  Coil fails to produce EMF
•  Subassembly leaks
•  Corroded
•  Cannot control speed
2.  Ask question as:
•  How could this system, design, component, subsystem, or
process fail?
•  Can it break, wear, bind, and so on?
3.  Fault tree analysis (FTA): In the FTA structure the top level is the
loss of the part function and then progressively on the lower
levels the failure modes are identified.
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
(14) Critical characteristics: The identification of the criticality or
significance in the design FMECA is only to designate special controls for
the process, assembly, and/or service FMECA.
Critical characteristics are identified when:
•  Process requirements can affect safety.
•  Process requirements can affect compliance with government
regulations.
•  Process requirements are necessary for special actions/
controls.
Example of possible critical
items
A good indication of
criticality is when
Severity is rated 9 or 10
with Occurrence and
Detection higher than 3.
Dimension
Specifications
Tests
Processes
Tooling
Usage
8"
97!
FILLING WORKSHEET
FILLING WORKSHEET
Design-FMECA Template
Design-FMECA Template
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
(15) Severity of effect: Severity is a rating indicating the seriousness of
the effect of the potential design failure mode.
•  The severity always applies to the effect of a failure mode.
In fact, there is a direct correlation between effect and
severity.
•  Severity is reviewed from the prospective of the system,
design itself, other systems, the product, the customer, and/
or the government regulations.
•  For evaluation purposes there usually is a rating table that
reflects the issues of the organization in conjunction with
the customer and/or the government regulations.
•  In the design FMECA the severity rating should be based
on the worst effect of the failure mode.
9"
10#
FILLING WORKSHEET
FILLING WORKSHEET
Design-FMECA Template
Design-FMECA Template
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
INTRODUCTION
(16) Potential Cause(s) of Failure: This area of FMECA is important because
76% of all engineering changes are due to corrections of bad design and only
24% are due to improvements. It is imperative that the focus in performing the
FMECA should be to identify all potential failures.
To do a good job of proper potential cause(s) of failure identification, one must
understand both the system and design, and ask appropriate questions:
•  “In what way can this system fail to perform its intended function?”
•  “What circumstances could cause the failure?”
•  “How or why can the part fail to meet its engineering specifications?”
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
The more one zoom s in on the root cause, the better one understands the
failure. Some of the techniques that may be used are:
•  Brainstorming
•  Cause-and-effect analysis
•  Analysis of the block diagram
•  Affinity charts
Note: if the effect of the failure is rated 8 through 10, special effort should be
made to identify as many root causes as possible.
11"
FILLING WORKSHEET
FILLING
WHORKSHEET
RISK ANALYSIS
Improper selection of
components parts
Failure to enforce process
and quality controls
Improper use of processes
Inadequate control
procedures
Improper installation,
maintenance
Human error
Misuse, abuse
Alteration of the product
Improper operating
instructions
Lack of safety devices,
environmental factors
Corrosion, galvanic
corrosion, crevice
corrosion
Stress concentration
Fatigue, uniform attack
Improper choice of
materials
Hydrogen damage, pitting,
blistering
Decarbonisation, abrasion
and wear, shock and
vibration
Interaction with other
components
Interaction with components
of other systems
Interaction with the
government
Interaction with the
customer
INTRODUCTION
(17) Occurrence (frequency): Is the rating value corresponding to the
estimated number of frequencies and/or cumulative number of failures that
could occur for a given cause over
the life of the design.
To identify the frequency for each of the causes you can use:
•  Reliability mathematics
•  Expected frequencies
•  Cumulative number of component failures (CNF/100 or CNF/
1000)
•  Examine similar or surrogate system and/or component for
similar information.
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Generally, the design FMECA operates under the assumption of a singlepoint failure (in other words, if the component fails, the system fails). A
single-point failure is defined as a component failure, which would cause
the system failure and is not compensated by redundancy or an alternative
method.
(18) Detection Method; Design Verification; Existing Control: The focus is
on the effectiveness of the control method/technique to catch the problem before
it reaches the customer. The objective is to detect a design deficiency as early
as possible.
There are different methods to detect a failure in the design as:
•  Brainstorming
•  Laboratory test
•  Design review
•  Finite element analysis
•  Computer simulation
•  Historical information
•  Information from similar components and/or similar components
Brainstorming
Note: When occurrence/frequency is calculated it must be for every single
cause of the
failure. If it cannot be estimated, then the
occurrence should be entered as 10.
Leading questions:
•  How can this failure be
discovered?
•  In what way can this
failure be recognized?
13#
14#
FILLING WORKSHEET
FILLING WORKSHEET
Design-FMECA Template
Design-FMECA Template
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
INTRODUCTION
(19) Detection: Is a rating corresponding to the likelihood that the proposed
design controls will detect a specific root cause of a failure mode before the
part is released for production.
To identify a detection rating one must estimate the ability for each of the
controls identified in item (18) to detect the failure before it reaches the
customer.
Note: If the ability of the controls to detect the failure is unknown or the
detection cannot be estimated, then the detection rating should be 10.
(20) Risk Priority Number (RPN): Is the product of Severity, Occurrence and
Detection. The RPN defines the priority of the failure.
In the design FMECA the goal is to reduce the RPN. It can be reduced by
reducing Severity, Occurrence and Detection:
•  Severity: can be reduced through a change in design.
•  Occurrence: can be reduced by improving engineering specifications and/or
requirements with the intent of preventing causes or reducing their
frequency.
•  Detection: can be reduced by adding or improving the design evaluation
technique or increasing sample size, and/or adding detection equipment.
15#
!
12#
Design-FMECA Template
INTRODUCTION
FMECA
PROCEDURE
Example of failure causes
Hardware failure due to
inadequate product design
FILLING WORKSHEET
Design-FMECA Template
PREPARATION
At this point, it must be emphasized that a major benefit of the design
FMECA is identification and removal of potential failure modes caused by
system and/or component interaction. These interaction also my involve
human factors and must be reviewed thoroughly.
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
(21) Recommended action: No FMECA should be done without a
recommended action. The idea of the recommended action in the design
FMECA is to reduce or eliminate design deficiencies and therefore
eliminate failures.
To facilitate this goal, the FMECA team must prioritize those failure modes
with the highest RPN, the highest severity, the highest occurrence.
Typical recommendations may be:
•  No action at this time
•  Add build-in detection devices
•  Provide alternatives to the design
•  Add redundant subsystem
(22) Responsible area or person and completion date: Identify the
responsible person/area and the target completion date for the recommended
action.
16#
98!
FILLING WORKSHEET
Design-FMECA Template
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
(23) Action taken: This is the follow up. It is imperative that someone (usually
the design engineer) will follow up on the recommendations to determine if
indeed they have been
addressed adequately, properly, and/or if they are in
need of updating.
Note: all FMECA are living document and such someone must be
responsible to update them.
(24) Revised RPN: After the action are incorporated in the design, the FMECA
team should
reevaluate the consequences of severity, occurrence and
detection. A new RPN must be calculated and the failures ranked.
This process is repeated as needed until such time the FMECA team
decides that all relevant
information has been covered.
! 
If no action are taken, these columns will remain blank.
17#
!
99!
1.5 Risk Analysis D-FMECA
Design FMECA Methodology
RISK ANALYSIS
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
FILLING
WHORKSHEET
FILLING
WHORKSHEET
RISK ANALYSIS
RISK ANALYSIS
Prioritize issues for
corrective action
Prioritize issues for
corrective action
Develop effective
recommended actions
Develop effective
recommended actions
Action Strategies to reduce
risk
Action Strategies to reduce
risk
Severity Ranking
Severity Ranking
Occurrence Ranking
Occurrence Ranking
Detection Ranking
Detection Ranking
FMECA Execution
Enablers
FMECA Execution
Enablers
Documentation Actions
Taken
Documentation Actions
Taken
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
Documentation Actions
Taken
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
1.  The FMECA team must adequately address all High severity
problems: It means, in a scale of 1-10, addressing all 9s and
10s at minimum. The FMECA team must review and fully
understand all the high severity issues so as to address them in
its recommended actions to ensure those issues do not occur
within the life of the product.
The intention is to ensure the FMECA team takes positive and
effective action to ensure high severity issues are fully
resolved.
2.  In addiction the FMECA team needs to review and prioritize
the high RPNs There different ways to do this:
!  RPN thresholds: not recommended.
!  Begin with the highest RPN and work down the list.
!  Rank the RPNs and address an agreed-upon percentage of
total issues.
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
Documentation Actions
Taken
RISK ANALYSIS
RISK ANALYSIS
1 - Prioritize issues for corrective action
INTRODUCTION
•  When assessing the degree of risk using the FMECA ranking scales,
it is not appropriate to compare the ratings of one team’s FMECA
with the ratings from another team.
PREPARATION
•  Even if the product or process appears to be similar, each application
is unique in terms of operating environment, customer usage, and
specific technical content.
FILLING
WHORKSHEET
•  The risk ranking scales, including RPN, are designed as a means to
prioritize issues for corrective actions within the scope of individual
FMECAs.
•  Regardless of which approach the FMECA team decides to use it is
crucial to address all high severities and all high RPNs until the level
of risk is acceptable.
FMECA
PROCEDURE
RISK ANALYSIS
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
!  Once we have all RPNs calculated and ordered, it can be useful to
built a Pareto-Chart (P-Chart).
A Pareto chart is a graphical overview of the process problems,
in ranking order of the most frequent, down to the least frequent,
in descending order from left to right. Thus, the Pareto diagram
illustrates the frequency of fault types. Using a Pareto, you can
decide which fault is the most serious or most frequent offender.
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
Prioritize issues for
corrective action
If the FMECA team has chosen to use severity and Occurrence,
and not RPN, they may want to plot the severity and occurrence
rankings on a risk matrix to graphically show risk prioritization.
1 - Prioritize issues for corrective action
RISK ANALYSIS
RISK ANALYSIS
1 - Prioritize issues for corrective action
1 - Prioritize issues for corrective action
INTRODUCTION
!
PREPARATION
Documentation Actions
Taken
RISK ANALYSIS
5 – Documentation actions taken
INTRODUCTION
This is the point at which the FMECA team must decide which issues
to address in the FMECA. There are two task involved:
FMECA Execution
Enablers
FILLING
WHORKSHEET
4 – FMECA Execution Enablers
RISK ANALYSIS
Documentation Actions
Taken
FMECA
PROCEDURE
3- Action strategies to reduce risk
1 - Prioritize issues for corrective action
Detection Ranking
PREPARATION
2 - Develop effective recommended actions
RISK ANALYSIS
INTRODUCTION
PREPARATION
1 - Prioritize issues for corrective action
1 - Prioritize issues for corrective action
INTRODUCTION
PREPARATION
Once the FMECA team has performed the analysis through Risk
Priority Number calculation, the important work of defining and
executing effective actions can begin.
INTRODUCTION
In FMECA, P-Chart are usually used for the following:
•  Comparison of RPNs between different failure modes of
the item analyzed and identification of high RPN failure
modes.
•  Comparison of total RPNs between items and identification
of high RPN items. The total RPN of each item is the
summation of RPNs of all failure modes of the item.
In either case, the team must set a cut-off value, where any failure
modes or items with an RPN above that point require further
attention.
Examples Pareto-Chart for comparison of RPNs between different
failure modes are given in figure in the next slides.
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
FMECA Execution
Enablers
Documentation Actions
Taken
Documentation Actions
Taken
100!
RISK ANALYSIS
RISK ANALYSIS
1 - Prioritize issues for corrective action
2 - Develop effective recommended actions
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
FILLING
WHORKSHEET
FILLING
WHORKSHEET
RISK ANALYSIS
RISK ANALYSIS
Prioritize issues for
corrective action
Prioritize issues for
corrective action
Develop effective
recommended actions
Develop effective
recommended actions
Action Strategies to reduce
risk
Action Strategies to reduce
risk
Severity Ranking
Severity Ranking
Occurrence Ranking
Occurrence Ranking
Detection Ranking
Detection Ranking
FMECA Execution
Enablers
FMECA Execution
Enablers
Documentation Actions
Taken
Documentation Actions
Taken
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
Documentation Actions
Taken
RISK ANALYSIS
RISK ANALYSIS
3- Action strategies to reduce risk
INTRODUCTION
•  Consider the full range of quality and reliability tools (See
tools section).
•  Review the corresponding engineer or manufacturing
requirements. The question needs to be asked, “Do the
engineering or manufacturing requirements need to be
changed to reflect the design or process improvements?”
•  not rely on process controls to overcome design weaknesses.
On the contrary, the focus of the Design FMECA team should
be on making the design more robust so that special process
controls are not required to resolve design deficiencies.
Moreover FMECA recommended actions should be effective,
detailed, and executable. They should have management agreement
and drive design improvements.
!  Remember, reduce risk from high severity first, followed by risk
from high RPNs. The most effective actions mitigate the effect to a
lower severity through design changes and improve the design to
make it more robust.
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
Documentation Actions
Taken
!
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
1 - Action Strategies to reduce Severity risk
•  Design for Fail-Safe: A fail-safe design is one that, in the event of
failure, responds in a way that will cause minimal harm to other devices
or danger to personnel. Fail-safe does not mean that failure is
improbable; rather, that a system’s design mitigates any unsafe
consequences of failure. In FMECA language, fail-safe reduces the
severity of the effect to a level that is safe. Example: Laminated safety
glass for windshields prevents injury from glass shards.
•  Design for Fault-Tolerance: A fault-tolerant design is a design that
enables a system to continue operation, possibly at a reduced level (also
known as graceful degradation), rather than failing completely when
some part of the system fails. In FMECA language, fault-tolerance
reduces the severity of the effect to a level that is consistent with
performance degradation. Example: A passenger car can have “run-flat”
tires, each of which contain a solid rubber core, allowing their use even
if a tire is punctured. The punctured “run-flat” tire is effective for a
limited time at a reduced speed.
Documentation Actions
Taken
RISK ANALYSIS
3- Action strategies to reduce risk
INTRODUCTION
1 - Action Strategies to reduce Severity risk
•  Design for Redundancy: A redundant design provides for the
duplication of critical components of a system with the intention of
increasing reliability of the system, usually in the case of a backup or
fail-safe. This means having backup components that automatically
“kick in” should one component fail. In FMECA language, redundant
design can reduce the occurrence of system failure and reduce system
severity to a safe level.
•  Provide Early Warning: Failures that occur without warning are more
dangerous than failures with warning. Catastrophic effects can be
avoided by adding a warning device to system design. In FMECA
language, adding early warning reduces the severity of the effect,
potentially reduces the occurrence of system failure, and increases
likelihood of detection of failure mode/cause during in-service usage.
Example: A tire manufacturer adds a tire pressure monitor to alert the
driver to unsafe tire pressure.
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
Documentation Actions
Taken
2 - Action Strategies to reduce Occurrence risk
•  Change the Design to Eliminate the Failure Mode or Cause: It is
possible to eliminate the failure mode or cause by changing the design of
the product or the process. In FMECA language, eliminating the failure
mode or cause will reduce the likelihood of occurrence to the lowest
possible level. Example: During the conversion from leaded to unleaded
fuel, there was a concern about consumers putting leaded fuel into a
vehicle designed for unleaded fuel. This concern was resolved by making
the gas tank opening too small for the leaded gas nozzle.
•  Design for Robustness and Other Design Optimization Techniques:
The objective of Robust Design is to optimize design parameters to make
the product design less sensitive to the effects of variation that is present in
the system’s input variables and parameters:
•  Taguchi methods are statistical methods using analysis of variance
with the objective of identifying design factors responsible for
degradation of performance.
•  Design of Experiments (DOE) is a technique for studying the factors
that may affect a product or process in order to identify significant
factors and optimize designs.
RISK ANALYSIS
RISK ANALYSIS
3- Action strategies to reduce risk
3- Action strategies to reduce risk
INTRODUCTION
INTRODUCTION
FMECA
PROCEDURE
FMECA
PROCEDURE
RISK ANALYSIS
Documentation Actions
Taken
PREPARATION
PREPARATION
3- Action strategies to reduce risk
INTRODUCTION
PREPARATION
In identifying recommended actions the FMECA team should:
•  take care to recommended feasible and effective actions that
will fully address the risk associated with each mode/cause.
•  consider existing controls, the relative importance
(prioritization) of the issues, as well as the cost and
effectiveness of corrective actions.
•  assign the person responsible, the due date, and other typical
project management type of information in order to be able to
execute the actions efficiently.
2 - Develop effective recommended actions
INTRODUCTION
PREPARATION
The FMECA team reviews each of the high severities and each of the
high RPNs, and develops the recommended actions that will reduce
risk to an acceptable level.
There is often more than one action needed to address risk associated
with each of the failure modes and causes.
2 - Action Strategies to reduce Occurrence risk
•  Use Physics-of-Failure Modeling of Failure Mechanisms:
Higher risk failure mechanisms can be analytically modeled to
reduce failures and obtain an accurate advanced warning of
impending failures.
•  Use a Factor-of-Safety: One of the most effective action
strategies to prevent failures is to design in a factor-of-safety. For
structural applications, this is the ratio of the maximum stress that
a structural part or other piece of material can withstand to the
maximum stress it is anticipated to experience in the use for which
it is designed. Essentially, how much stronger the system is than it
usually needs to be for an intended load. The greater the factor-ofsafety, the lower the likelihood of structural failure. In FMECA
language, increasing the factor-of-safety reduces the frequency of
the cause of the failure mode.
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
Severity Ranking
Occurrence Ranking
Detection Ranking
2 - Action Strategies to reduce Occurrence risk
•  Change the Way the Product or Process Interacts with the Environment:
The FMECA team can recommend changes in the way the product or process
interacts with the environment, which can reduce the frequency of the cause of
failure.
•  Change the Way the User Interacts with the Product: The FMECA team
can recommend changes to the way the user or operator interacts with the
product or process, which can reduce the frequency of the cause of failure.
•  Error Proof a Product Design: It is possible to change the product design so
that errors in manufacturing or assembly processing are reduced or eliminated.
•  Error Proof the Manufacturing Process: The manufacturing or assembly
process can be changed so that processing errors are reduced or eliminated. In
FMECA language, error proofing a product design or a manufacturing process
reduces the frequency of the cause of the failure mode.
FMECA Execution
Enablers
Documentation Actions
Taken
101!
RISK ANALYSIS
RISK ANALYSIS
3- Action strategies to reduce risk
3- Action strategies to reduce risk
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
INTRODUCTION
2 - Action Strategies to reduce Occurrence risk
•  Error Proof the Product Use: The operation of products or
equipment can be designed so that unsafe operation is not possible.
Example: In order to activate a metal stamping machine, two
buttons (separated by at least 3 feet) must be simultaneously
pushed.
Example: A kerosene space heater is designed to immediately
turn off if it falls over.
•  Use Statistical Process Control to Monitor and Control
Manufacturing Processes: Statistical Process Control (SPC) is the
application of statistical methods to measure and analyze the
variation in manufacturing (or other) processes, with the objective
of getting and keeping processes under control and producing conforming products. SPC can be used to maintain the consistency of
how the product is made. Properly used, SPC can significantly
reduce defects in the manufacturing process.
Documentation Actions
Taken
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
RISK ANALYSIS
INTRODUCTION
3 - Action Strategies to reduce Detection risk
•  Use Improved Test Strategies, Such as Degradation Testing,
Accelerated Testing, and/or Test-To-Failure: The risk due to
inadequate design controls can be reduced by changing the type of
test. Traditional pass–fail testing introduces risk by not detecting or
understanding the cause of failure. Where possible, it is important
to test to failure and use degradation testing to understand the
progression of failure. Strategies such as Highly Accelerated Life
Testing (HALT), Accelerated Life Testing (ALT), and degradation
testing can markedly improve detection risk.
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
Severity Ranking
Occurrence Ranking
Detection Ranking
Detection Ranking
FMECA Execution
Enablers
FMECA Execution
Enablers
Documentation Actions
Taken
Documentation Actions
Taken
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
1.  What can be done to reduce severity to a safe level by modifying the design?
2.  Which of the ‘Action Strategies to Reduce Severity Risk’ should be
recommended?
3.  How can the current design be made safer?
4.  If the product fails, how can the user be protected from potential harm or
injury?
5.  What can be done to reduce likelihood of occurrence to a very low level?
6.  Which of the ‘Action Strategies to Reduce Occurrence Risk’ should be
recommended?
7.  How can the current design be made more robust?
8.  What can be done to reduce likelihood of detection to a very low level?
9.  Which of the ‘Action Strategies to Reduce Detection Risk’ should be
Recommended?
10.  What tests or evaluation techniques need to be added or modified to improve
detection capability?
11.  Are there any other actions that are needed to reduce risk to an acceptable
level?
12.  If the recommended actions are implemented, will that be sufficient to
address all high severity and high RPN risk?
RISK ANALYSIS
RISK ANALYSIS
4 – FMECA Execution Enablers
INTRODUCTION
Once all of the FMECA recommended actions are identified, the
FMECA team should be confident that they have identified all of the
necessary tasks and actions to reduce risk to an acceptable level, that
is, design-related risk.
The following are key elements for ensuring timely execution of
FMECA recommended actions:
1.  Recommended Actions Are Well Defined: Each recommended
action should be thoroughly defined so that the end result is clear
and so that someone who is not involved in the FMECA can
understand what is being recommended.
2.  Recommended Actions Include Specific Information:
•  Responsible Person
•  Action Category
•  Target Completion Date
•  Review and Approved by
Documentation Actions
Taken
INTRODUCTION
Thought-Starter Questions: When identifying recommended actions the team
can be asked questions such as:
4 – FMECA Execution Enablers
INTRODUCTION
FILLING
WHORKSHEET
•  Develop New Detection-Type Controls to Increase the Likelihood of
Detection of the Cause: The FMECA team may decide to develop new
detection-type controls that do not currently exist. In FMECA language,
by adding the newly developed detection-type controls, the likelihood of
detecting the cause of the failure can be increased.
3- Action strategies to reduce risk
Severity Ranking
FMECA
PROCEDURE
•  Modify Existing Detection-Type Controls to Increase the Likelihood
of Detection of the Cause: The FMECA team can recommend changes
to the existing detection-type controls to increase the likelihood of
detection of the cause.
RISK ANALYSIS
Occurrence Ranking
PREPARATION
3 - Action Strategies to reduce Detection risk
•  Utilize Existing Detection-Type Controls to Increase the Likelihood
of Detection of the Cause: The FMECA team may decide to utilize
detection-type controls that already exist but were not currently used to
detect the failure mode or cause being analyzed. If selected properly, the
detection-type controls can increase the likelihood of detection of the
cause of failure.
3- Action strategies to reduce risk
Action Strategies to
reduce risk
!
FMECA
PROCEDURE
Documentation Actions
Taken
INTRODUCTION
PREPARATION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
3.  Recommended Actions Are Energetically Followed Up: A process needs
to be in place to follow up with the responsible person and assess
status and inform management if there are execution problems. Status
is reported back to the FMECA team who enters it into the FMECA
database. When completed, Actions Taken are recorded in the FMECA
worksheet and the team must ensure those actions reduce risk to an
acceptable level.
4.  Execution Problems Are Quickly Identified and Resolved: It is
important for the responsible person to communicate problems in
execution quickly to the FMECA team as well as to management. The
FMECA team may be able to resolve these by redefining the action or
reassigning the action item. If not, the FMECA team must elevate
execution problems quickly to management.
5.  Management Reviews All High Severity and High RPN Issues. It is
essential that management regularly review the status of FMECA
action items for both high severities and high RPNs. Feedback from
management goes back to FMECA teams for review and incorporation.
Documentation Actions
Taken
RISK ANALYSIS
RISK ANALYSIS
4 – FMECA Execution Enablers
4 – FMECA Execution Enablers
6.  The FMECA Team Remains Actively Involved until All FMECA
Recommended Actions Have Been Executed: The FMECA team
should meet regularly, or on an ad hoc basis, to review the status
of all FMECA recommended actions. These post-analysis
meetings have the purpose of:
•  documenting actions taken
•  ensuring proper execution
•  recommending “workarounds” if issues with execution arise
•  bringing execution problems to the attention of management
•  ensuring risk is reduced to an acceptable level
Too often omitted, this follow-up activity by the FMECA team is
critical in successful application of FMECA. In many companies, the
FMECA team ceases to meet and is dissolved once the recommended
actions are developed. The important thing is for the team to stay
vigilant and active all the way through full implementation of the
actions, particularly on the high-risk issues.
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Example of recommended actions for all-terrain Hand Brake Design FMECA.
Detection Ranking
FMECA Execution
Enablers
FMECA Execution
Enablers
Documentation Actions
Taken
Documentation Actions
Taken
102!
RISK ANALYSIS
5 – Documentation actions taken
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
•  The FMECA team documents the specific actions taken to
implement the recommended actions. Care should be taken to
ensure that the correct actions were implemented and that the risk
is reduced to an acceptable level.
•  Once the FMECA recommended actions are implemented and
the actions taken documented in the FMECA worksheet, the
FMECA team must reassess each of the risk rankings for
severity, occurrence, and detection. This risk reassessment is very
important because it shows how well the risk associated with
each failure mode and associated cause is reduced as a result of
the specific actions from the FMECA
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
Documentation Actions
Taken
!
103!
2 ALLEGATO - Machinery FMECA
2.1 Introduction M-FMECA
!
!
INTRODUCTION
Machinery-FMECA Methodology
What is FMECA ?
INTRODUCTION
INTRODUCTION
What is M-FMECA?
What is FMECA?
Types of FMECA
Types of FMECA
FMECA Objectives
FMECA Objectives
What can FMECA be
used for?
What can FMECA be
used for?
Standards and Guidelines
Standards and Guidelines
When to perform a
FMECA
When to perform a
FMECA
Definitions and
Examples
Definitions and
Examples
Preliminary Risk
Assessment
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
!!!
1
RISK ANALYSIS
Failure modes, effects and criticality analysis (FMECA) is a
methodology to identify and analyze:
• All potential failure modes of the various parts of a system
• The effects these failures may have on the system
• How to avoid the failures, and/or mitigate the effects of the failures
on the system
“FMECA is a technique used to identify, prioritize, and eliminate
potential failures from the system, design or process before they reach
the costumer”
Omdahl (1988)
“FMECA is a technique to resolve potential problems in a system
before they occur”
Sematech (1992)
RISK ANALYSIS
2
INTRODUCTION
INTRODUCTION
Types of FMECA
What is FMECA ?
INTRODUCTION
INTRODUCTION
What is FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
What is M-FMECA?
• An FMECA is an engineering analysis done by a cross-functional
team of subject matter experts that thoroughly analyzes product
designs early in the product development process. Its objective is
finding and correcting weaknesses before the product gets into the
hands of the customer.
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
• An FMECA should be the guide to the development of a complete
set of actions that will reduce risk associated with the system,
subsystem, and component or manufacturing/assembly process to
an acceptable level.
Standards and Guidelines
When to perform a
FMECA
Definitions and
Examples
• If effectively used throughout the product life cycle, it will result in
significant improvements to reliability, safety, quality, delivery, and
cost.
RISK ANALYSIS
Preliminary Risk
Assessment
3
!!!
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
System
Design
Components
Components
Subsystems
Subsystems
Main
systems
Main
systems
Human
resources
Task
Work station
Service lines
Services
Performance
Operators
training
Process
Manpower
Machine
Method
Material
Measurement
Environment
Machinery
Focus on
Tools
Work station
Production
lines
Processes
Gauges
Operators
training
4
!
6
!
INTRODUCTION
Types of FMECA
Types of FMECA
!
Service
Manpower
Human
resources
Machine
Method
Material
Measurement
Environment
RISK ANALYSIS
INTRODUCTION
INTRODUCTION
INTRODUCTION
What is M-FMECA?
What is M-FMECA?
Types of FMECA
Types of FMECA
FMECA Objectives
FMECA Objectives
What can FMECA be
used for?
What can FMECA be
used for?
Standards and Guidelines
Standards and Guidelines
When to perform a
FMECA
When to perform a
FMECA
Definitions and
Examples
Definitions and
Examples
Preliminary Risk
Assessment
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
!
5
!!!
RISK ANALYSIS
Design FMECAs should be done at the subsystem and/or component
level when new designs begin development or when existing designs
will be changed sufficiently so that there are concerns about risk.
Is used to analyze products, high volume tools or standard machines,
machine components, standard production tooling, etc., before they
are released to production.
• Focuses on potential failure modes of products caused by design
deficiencies.
• Focuses on parts that can be prototyped and tested or modeled
before high volume production of the product is launched.
104!
INTRODUCTION
INTRODUCTION
Types of FMECA
Types of FMECA
INTRODUCTION
INTRODUCTION
What is M-FMECA?
Types of FMECA
Machinery FMECAs are treated as a variation of a design FMECA.
The predominant focus on this variation is on identifying safety and
reliability issues.
What is M-FMECA?
Is used to analyze low-volume specialty machinery (equipment and
tools), that allows for customized selection of component parts,
machine structure, tooling, bearings, coolants, etc.
• Focuses on designs that improve the reliability and
maintainability of the machinery for long-term plant usage.
• Considers preventive maintenance as a control to ensure
reliability.
• Considers limited volume, customized machinery where large
scale testing of a number of machines is impractical prior to
production and manufacture of the machine.
• Considers parts that can be selected for use in the machine, where
reliability data is available or can be obtained before production
use.
What can FMECA be
used for?
Types of FMECA
FMECA Objectives
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
7
!!!
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
What can FMECA be
used for?
Standards and Guidelines
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
Traditional Design-FMECA is stretched to its limits when it is applied to
machinery and equipment. This is because the primary focus of
Machinery-FMECA is on reliability rather than the issue of actual
availability, which is so important when it comes to machinery and
equipment.
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Therefore for all intended purpose, the majority of M-FMECA are
treated as a variation of a Design FMECA. The predominant focus of
this variation is on identifying safety and reliability issues.
Standards and Guidelines
When to perform a
FMECA
The Machinery FMECA (MFMECA) information has been provided due
to the importance of Plant Machinery and Equipment functioning as
intended in manufacturing and assembly plants.
Definitions and
Examples
Preliminary Risk
Assessment
The use of the MFMECA, on Plant Machinery and Equipment, will
assist with the identification of potential failure modes, so that design
and processing alternatives can be considered, prior to finalizing the
Plant Machinery and Equipment Designs.
!!!
9
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
When to perform a
FMECA
Since the Machinery-FMECA can be considered as a variation of
Design-FMECA focusing on safety and reliability, the following
methodologies will be similar in most of their parts.
What is M-FMECA?
Differences between the two methodologies regard:
What can FMECA be
used for?
FMECA Objectives
• Filling worksheet
• Scales
• Templates
Standards and Guidelines
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
11
!
!
!!!
FMECA Objectives
Standards and Guidelines
When to perform a
FMECA
!
!
The Machinery Potential FMECA supports the design process in
reducing risk of failures by:
1. Aiding in the objective evaluation of equipment functions, design
requirements and design alternatives.
2. Increasing the probability that potential failure modes and their
effects on the machinery have been considered in the design and
development process.
3. Providing additional information to aid in the planning of
thorough and efficient design, validation and development
programs.
4. Developing a ranked list of potential failure modes ranked
according to their effect on the customer, thus establishing a
priority system for design improvements, development and
validation testing/analysis.
12
RISK ANALYSIS
INTRODUCTION
FMECA Objectives
What can FMECA be used for?
!
INTRODUCTION
What is M-FMECA?
5. Providing future reference, e.g. lessons learned to aid in
analyzing field concerns, evaluating design changes and
developing advanced machinery designs.
6. Improve the reliability and durability of the machinery, resulting
in reduced life cycle cost.
7. Improves machinery maintainability resulted in reduced mean
time to repair.
8. Improves reliability, durability and maintainability of the
machinery, resulting in increased machinery availability
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform a
FMECA
Definitions and
Examples
Definitions and
Examples
Preliminary Risk
Assessment
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
10
INTRODUCTION
INTRODUCTION
What can FMECA be
used for?
• The severity, occurrence, and detection tables used are tailored to
meet the needs of the machinery design engineer in order to
maintain a standard interpretation across a wide variety of
machinery designs.
Types of FMECA
Preliminary Risk
Assessment
Types of FMECA
• Machinery FMECAs are targeted for long-term, repetitive cycles,
where wear out is a prime consideration. For example, machinery
running at two 10-hours shifts per day, 50 weeks per year, will
accumulate 120,000 hours of operation in twenty years. This
would be equivalent to a vehicle being driven 600,000 miles at
an average speed of 50mph.
FMECA Objectives
Definitions and
Examples
What is M-FMECA?
• Machinery FMECAs are used for relatively low volume designs,
where statistical failure data on prototypes is not practical to be
obtained by the manufacturer.
INTRODUCTION
FMECA Objectives
Standards and Guidelines
• Product Design FMECAs are intended for high production
systems/subsystems and components. Prototype or surrogate part
testing is used to verify design intent.
INTRODUCTION
INTRODUCTION
What can FMECA be
used for?
The key differences between Design and Machinery FMECA are:
RISK ANALYSIS
Types of FMECA
Types of FMECA
!
What is M-FMECA?
INTRODUCTION
What is M-FMECA?
8
Types of FMECA
INTRODUCTION
RISK ANALYSIS
The Machinery FMECA is a living document and should:
• be initiated during design concept development
• be continually updated as changes occur or additional information
is obtained throughout the phases of machinery development
• should be completed before engineering release for construction
INTRODUCTION
INTRODUCTION
FMECA Objectives
The M-FMECA is a design output used to evaluate and improve the
reliability, maintainability and the durability of the machinery.
RISK ANALYSIS
Types of FMECA
Types of FMECA
The Machinery-FMECA supports the machinery design process from design
development through design approval.
Standards and Guidelines
INTRODUCTION
What is M-FMECA?
Failure Mode Effects and Criticality Analysis concepts can be applied to
machinery (the term machinery includes tooling and equipment) to reduce
the probability that potential failure modes, related to the machinery, will
occur.
13
!!!
RISK ANALYSIS
! Assist in selecting design alternatives with high reliability and
high safety potential during the early design phases
! Ensure that all conceivable failure modes and their effects on
operational success of the system have been considered
! List potential failures and identify the severity of their effects
Develop early criteria for test planning and requirements for
test equipment
! Provide historical documentation for future reference to aid in
analysis of field failures and consideration of design changes
! Provide a basis for maintenance planning
! Provide a basis for quantitative reliability and availability
analyses.
14
!
105!
INTRODUCTION
What is M-FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and
Guidelines
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
INTRODUCTION
INTRODUCTION
FMECA Standards and Guidelines
FMECA Standards and Guidelines
INTRODUCTION
STANDARDS:
Types of FMECA
What is M-FMECA?
Types of FMECA
FMECA Objectives
! IEC 60812 “Procedures for failure mode and effect analysis
(FMEA)”
Standards and
Guidelines
! SAE ARP 5580 “Recommended failure modes and effects
analysis (FMEA) practices for non-automobile applications”
Preliminary Risk
Assessment
! SEMATECH (1992) “Failure Modes and Effects Analysis
(FMEA): A Guide for Continuous Improvement for the
Semiconductor Equipment Industry”
15
!!!
INTRODUCTION
When to perform an FMECA
INTRODUCTION
The FMECA should be initiated as early in the design process,
where we are able to have the greatest impact on the equipment
reliability. The locked-in cost versus the total cost of a product is
illustrated in the figure:
What is M-FMECA?
Types of FMECA
FMECA Objectives
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
!!!
17
!
!
INTRODUCTION
FMECA Definitions and Examples: Item
INTRODUCTION
What is M-FMECA?
This section covers the basic definitions of FMECA and examples
from different applications.
Types of FMECA
• The time spent toward understanding the fundamental concepts
and definitions of FMECA will shorten the time in meetings and
help ensure high quality results.
What can FMECA be
used for?
Standards and Guidelines
Standards and Guidelines
• The definitions are presented in the sequence they are normally
developed in a FMECA project
When to perform a
FMECA
Definitions and
Examples
Definitions and
Examples
Preliminary Risk
Assessment
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
19
!
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
An “item” is the focus of the FMECA project. For a MachineryFMECA, this is the subsystem, for a Machinery-FMECA is the
machine or component under analysis.
FMECA Objectives
FMECA Objectives
Standards and Guidelines
!
18
RISK ANALYSIS
INTRODUCTION
What is M-FMECA?
What can FMECA be
used for?
Figure above describes the increasing costs of finding and fixing
problems depending on when the problems are discovered. The later
problems are found in the product development process, the more it
costs to fix them, symbolized by factors of 10.
FMECA Definitions and Examples
INTRODUCTION
Types of FMECA
!
16
INTRODUCTION
Definitions and
Examples
FMECA Objectives
NASA NHB 5300.4, "Reliability Program Provisions for
Aeronautical and Space Contractors" This document is similar in
some respects to MIL-STD-785. It imposes the requirement to perform
an FMECA and gives guidance as to when the task is to be performed
and to what depth it should be done but it does not dictate how the
analysis is to be performed.
RISK ANALYSIS
Standards and Guidelines
What is M-FMECA?
•
When to perform an FMECA
RISK ANALYSIS
!
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
When to perform a
FMECA
INTRODUCTION
MIL-STD-1543, "Reliability Program Requirements for Space and
Launch Vehicles" This document is similar in many respects to MILSTD-785. imposes the requirement to perform Task 204, "Failure Mode,
Effects and Criticality Analysis." It gives guidance as to when the task is
to be performed and to what depth it should be done but does not dictate
how the analysis is to be performed.
Definitions and
Examples
! SAE J1739 “Potential Failure Mode and Effects Analysis in
Design (Design FMEA) and Potential Failure Mode and Effects
Analysis in Manufacturing and Assembly Processes (Process
FMEA) and Effects Analysis for Machinery (Machinery FMEA)”
Standards and Guidelines
When to perform a
FMECA
•
When to perform a
FMECA
What can FMECA be
used for?
What can FMECA be
used for?
MIL-STD-785, "Reliability Program for Systems and Equipment
Development and Production" This standard imposes the requirement
to perform Task 204, "Failure Mode, Effects and Criticality Analysis." It
gives guidance as to when the task is to be performed and to what depth
it should be done. It does not dictate how the analysis is to be performed.
What can FMECA be
used for?
! BS 5760-5 “Guide to failure modes, effects and criticality
analysis (FMEA and FMECA)”
What can FMECA be
used for?
Types of FMECA
•
FMECA Objectives
!
INTRODUCTION
GUIDELINES:
What is M-FMECA?
! MIL-STD 1629 “Procedures for performing a failure mode and
effect analysis”
!!!
Examples of Items:
Item: Power steering pump
Item: Shaft (part of rock grinding equipment)
Item: Projector lamp
Item: Oven burner assembly
Item: Hydraulic fluid tank
Item: Robotic transfer device
RISK ANALYSIS
INTRODUCTION
INTRODUCTION
FMECA Definitions and Examples : Function
FMECA Definitions and Examples: Failure Mode
INTRODUCTION
A “function” is what the item is intended to do, usually to a given
standard of performance or requirement.
For Machinery FMECAs, this is the primary purpose of the item;
wording should consider “Do this [operation] to this [the part] with
this [the tooling]” along with any needed requirement. There can be
many functions for each item or operation. Functions are typically
described in a verb–noun format.
What is M-FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
Examples of Functions:
• Item: Power steering pump
Function: Delivers hydraulic power for steering by transforming
oil pressure at inlet (xx psi) into higher oil pressure at outlet (yy
psi) during engine idle speed
• Item: Oven burner assembly
Function: Heat the burner plate to 160°F within 60 seconds
• Item: Hydraulic fluid tank
Function: Contain the XYZ hydraulic fluid in tank, with no
external leakage per specification #456
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
21
!!!
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
20
!
22
!
A “failure mode” is the manner in which the item or operation
potentially fails to meet or deliver the intended function and associated
requirements.
There may be many failure modes for each function.
Failure modes may include failure to perform a function within defined
limits, inadequate or poor performance of the function, intermittent
performance of a function, and/or performing an unintended or
undesired function.
Examples of Failure Modes:
• Item: Power steering pump
Function: Delivers hydraulic power for steering by transforming
oil pressure at inlet (xx psi) into higher oil pressure at outlet [yy
psi] during engine idle speed
Failure Mode: Inadequate outlet pressure [less than yy psi]
• Item: Shaft (part of rock grinding equipment)
Function: Provide mechanical transfer of [xx] rotational force
while maintaining linear and angular stability
Failure Mode: Shaft fractured
106!
INTRODUCTION
What is M-FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
INTRODUCTION
INTRODUCTION
FMECA Definitions and Examples: Effect
FMECA Definitions and Examples: Severity
Example of Effects:
Item: Power steering pump
Function: Delivers hydraulic power for steering by transforming oil
pressure at inlet (xx psi) into higher oil pressure at outlet [yy psi] during
engine idle speed.
Failure Mode: Inadequate outlet pressure [less than yy psi]
Effect (Local: Pump): Low pressure fluid goes to steering gear
Effect (Next level: Steering Subsystem): Increased friction at steering
gear
Effect (End user): Increased steering effort with potential accident
during steering maneuvers.
23
!
INTRODUCTION
What is M-FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
!!!!
FMECA Objectives
Standards and Guidelines
When to perform a
FMECA
What is M-FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Example of Causes:
Item: Power steering pump
Function: Delivers hydraulic power for steering by transforming oil
pressure at inlet (xx psi) into higher oil pressure at outlet ([yy] psi)
during engine idle speed
Failure Mode: Inadequate outlet pressure (less than [yy] psi)
Effect (Local: Pump): Low pressure fluid goes to steering gear
Effect (Next level: Steering Subsystem): Increased friction at steering
gear
Effect (End user): Increased steering effort with potential accident
during steering maneuvers
Cause: Fluid incorrectly specified (viscosity too low)
Standards and Guidelines
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
25
!!!!
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
Criteria:,Severity,of,effects
Ranking
Affects'operator,'plant'or'maintenance'personnel,'safety'and/or'
Affects'operator,'plant'or'maintenance'personnel,'safety'and/or'
affects'non'compliance'with'government'regulations,'with'
warning
9
Very,high
Downtime'more'than'8'hours'or'the'production'of'defective'
parts'for'more'than'4'hours
8
High
Downtime'between'4'and'8'hours'or'the'production'of'
defective'parts'for'more'than'4'hours
7
Moderate
Downtime'between'1'and'4'hours'or'the'production'of'
defective'parts'between'1'and'2'hours
6
Low
Downtime'between'30'minutes'and'1'hour'or'the'production'of'
defective'parts'up'to'1'hour
5
Very,low
Downtime'between'10'and'30'minutes'but'no'production'of'
defective'parts
4
Minor
Downtime'up'to'10'minutes'but'no'production'of'defective'
parts
3
Very,minor
Process'parameter'variability'not'within'specification'limits.'
Adjustments'or'other'process'controls'need'to'be'taken'during'
production.'No'downtime'and'no'production'of'defective'parts.
2
None
Process'parameter'variability'within'specification'limits.'
Adjustments'or'other'process'controls'can'be'done'during'
normal'maintenance.
1
R(t)=20%:)MTBF)about)60%)of)the)user's)
required)time
R(t)=37%:)MTBF)equal)to)the)user's)required)
time
1)in)24
8
1)in)90.000
1)in)80
7
R(t)=60%:)MTBF)2)times)greater)than)the)user's)
required)time
1)in)180.000
1)in)36.000
1)in)350
6
R(t)=78%:)MTBF)4)times)greater)than)the)user's)
required)time
1)in)270.000
1)in)1000
5
R(t)=85%:)MTBF)6)times)greater)than)the)user's)
required)time
1)in)360.000
1)in)2500
4
R(t)=90%:)MTBF)10)times)greater)than)the)user's)
required)time
1)in)540.000
1)in)5000
3
R(t)=95%:)MTBF)20)times)greater)than)the)user's)
required)time
1)in)900.000
1)in)10000
2
1)in)25000
1
R(t)=98%:)MTBF)50)times)greater)than)the)user's) 1)in)more)tha)900.000)
required)time
cycles
INTRODUCTION
Examples of Controls:
Item:
Power
steering
pump
Function: Delivers hydraulic power for steering by transforming oil
pressure at inlet ([xx] psi) into higher oil pressure at outlet ([yy] psi)
during engine idle speed
Failure Mode: Inadequate outlet pressure (less than [yy] psi)
Effect (Local: Pump): Low pressure fluid goes to steering gear
Effect (Next level: Steering Subsystem): Increased friction at steering gear
Effect (End user): Increased steering effort with potential accident during
steering maneuvers
Cause: Fluid incorrectly specified (viscosity too low)
Prevention Control: Guidelines for hydraulic fluid selection
Detection Control: Vehicle durability test #123
What can FMECA be
used for?
Types of FMECA
FMECA Objectives
Standards and Guidelines
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
Poorly worded example of Prevention Control: Machinery guideline
Poorly worded example of Detection Control: Vehicle durability test
27
!!!!
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Effects
Suggested(M*FMECA(Detection(Evaluation(Criteria
Detection
Design'or'machinery'controls'cannot'detect'a'potential'cause'and'subsequent'failure'or'there'are'
no'design'or'machinery'controls.
Very'remote'chance'that'design'or'machinery'controls'will'detct a'potential'cause'and'subsequent'
Very1remote
failure'mode.
Definitions
and
remote'change'that'design'or'machinery'controls'will'detect'a'potential'cause'and'subsequent'
Remote
Examplesfailure'mode.'Machinery'control'will'provide'indication'of'failure.
FMECA Objectives
What can FMECA be
used for?
• severity of the effect
• likelihood of occurrence of the cause
• likelihood of detection of the cause.
Standards and Guidelines
When to perform a
FMECA
Use of RPN is further explained
Definitions and
Examples
Preliminary Risk
Assessment
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
29
!!!
RISK ANALYSIS
30
!
9
8
Very1Low
7
Low
low'change'that'design'or'machinery'controls'will'detect'a'potential'cause'and'subsequent'failure'
mode.'Machinery'control'will'provide'an'indicator'of'imminent'failure.
6
Moderate
medium'change'design'controls'will'detect'a'potential'cause'and'subsequent'failure'mode.'
Machinery'control'will'prevent'imminent'failure.
5
Moderately1 moderately'high'chance'design'controls'will'detect'a'potential'cause'and'subsequent'failure'mode.'
Machinery'control'will'prevent'imminetn failure.
high
4
High
High'chance'that'design'controls'will'detect'a'potential'cause'and'subsequent'failure'mode.'
Machinery'control'will'prevent'imminent'failure'and'isolate'the'cause.
3
Very1High
very'high'chance'that'design'controls'will'detect'a'potential'cause'and'subsequent'failure'mode.'
Machinery'controls'may'not'be'required.
2
Almost1certain
Design'controls'almost'certain'to'detect'a'potential'cause'and'subsequent'failure'mode.'Machinery'
controls'not'required.
1
INTRODUCTION
Types of FMECA
!
10
Design'or'machinery'controls'do'not'prevent'the'failure'from'occurring.'Machinery'control'will'
isolate'the'cause'and'subsequent'failure'after'the'failure'has'occurred.
FMECA Definitions and Examples: Recommended Actions
What is M-FMECA?
28
Rank
Almost1
impossible
INTRODUCTION
INTRODUCTION
!
“Detection” is a ranking number associated with the best control
from the list of detection-type controls, based on the criteria from the
detection scale.
The detection ranking considers the likelihood of detection of the failure
mode/cause, according to defined criteria.
FMECA Definitions and Example: Risk Priority Number
Risk Priority Number (RPN) is a numerical ranking of the risk
of each potential failure mode/cause, made up of the arithmetic
product of the three elements:
26
Criteria:(Occurrences(as( Occurrences(as(Possible(
Criteria:(Occurrences(as(Reliability(based(on(the( Possible(number(of(
number(of(Failures(
Ranking
user's(required(time
Failures(within(cycles(of(
within(Hours(of(
operation
Operation
R(t)<1%:)MTBF)about)10%)of)the)user's)required)
1)in)90
1)in)1
10
time
R(t)=5%:)MTBF)about)30%))of)the)user's)
1)in)900
1)in)8
9
required)time
FMECA Definitions and Examples: Detection
What is M-FMECA?
!
Suggested(M*FMECA(Occurrence(Evaluation(Criteria
The criteria for
these scales
should be
reviewed and
tailored (as
needed) to make
sense for
individual
company
applications
INTRODUCTION
INTRODUCTION
24
For Machinery-FMECAs, the occurrence ranking considers the likelihood
of occurrence during the life of the product.
FMECA Definitions and Examples: Control
“Controls” are the methods or actions currently planned, or are already in place,
to reduce or eliminate the risk associated with each potential cause. Controls can
be the methods to prevent or detect the cause during product development, or
can be actions to detect a problem during service before it becomes catastrophic.
There can be many controls for each cause.
10
Hazardous,(with,
warning)
“Occurrence” is a ranking number associated with the likelihood that the
failure mode and its associated cause will be present in the item being
analyzed.
RISK ANALYSIS
Definitions and
Examples
RISK ANALYSIS
!
RISK ANALYSIS
INTRODUCTION
A “cause” is the specific reason for the failure, preferably found by
asking “why” until the root cause is determined. For Machinery
FMECAs, the cause is the deficiency that results in the failure mode.
In most applications, particularly at the component level, the cause is
taken to the level of failure mechanism, which is further explained.
By definition, if a cause occurs, the corresponding failure mode occurs.
There can be many causes for each failure mode.
INTRODUCTION
What can FMECA be
used for?
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
Suggested(M*FMECA(Severity(Evaluation(Criteria
Effects
Hazardous,
affects'non'compliance'with'government'regulations,'without'
(without,warning)
warning
INTRODUCTION
!
!
Types of FMECA
In the adjacent
figure you can see
an example of
severity scale for
M-FMECA from
the Automotive
industry Action
Group (AIAG).
FMECA Definitions and Examples Occurrence
RISK ANALYSIS
What is M-FMECA?
“Severity” is a ranking number associated with the most serious effect for a
given failure mode, based on the criteria from a severity scale. It is a
relative ranking within the scope of the specific FMECA.
INTRODUCTION
!
What is M-FMECA?
What is M-FMECA?
FMECA Definitions and Examples: Cause
RISK ANALYSIS
INTRODUCTION
INTRODUCTION
An “effect” is the consequence of the failure on the system or end user.
Depending on the ground rules for the analysis, the team may define a single
description of the effect on the top-level system and/or end user, or three
levels of effects:
• Local Effect: The consequence of the failure on the item or adjacent items
• Next Higher Level Effect: The consequence of the failure on the next
higher level assembly
• End Effect. The consequence of the failure on the top-level system and/or
end user
“Recommended actions” are the tasks recommended by the FMECA team to
reduce or eliminate the risk associated with potential causes of failure.
Recommended actions should consider the existing controls, the relative
importance (prioritization) of the issue, and the cost and effectiveness of the
corrective action. There can be many recommended actions for each cause.
Examples of Recommended Actions:
Item: Power steering pump
Function: Delivers hydraulic power for steering by transforming oil
pressure at inlet ([xx] psi) into higher oil pressure at outlet [yy] psi during
engine idle speed
Failure Mode: Inadequate outlet pressure (less than [yy] psi)
Effect (Local: Pump): Low pressure fluid goes to steering gear
Effect (Next level: Steering Subsystem): Increased friction at steering gear
Effect (End user): Increased steering effort with potential accident during
steering maneuvers
Cause:
Fluid
incorrectly
specified
(viscosity
too
low)
Prevention Control: Guidelines for hydraulic fluid selection Detection
Control: Vehicle durability testing #123
Recommended Action: Increase fluid viscosity to standard #xyz
Poorly worded example of Recommended Action: Change fluid
viscosity
107!
INTRODUCTION
INTRODUCTION
FMECA Definitions and Examples: Recommended Actions
Preliminary Risk Assessment
INTRODUCTION
INTRODUCTION
What is M-FMECA?
What is M-FMECA?
Types of FMECA
Types of FMECA
FMECA Objectives
FMECA Objectives
What can FMECA be
used for?
What can FMECA be
used for?
Standards and Guidelines
Standards and Guidelines
When to perform a
FMECA
When to perform a
FMECA
Definitions and
Examples
Definitions and
Examples
Preliminary Risk
Assessment
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
Figure: Example of causes, controls and recommended actions for a disk brake
system.
RISK ANALYSIS
31
!
!!!
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
Open up a simple spreadsheet, in the first column, list the complete
subsystem or component hierarchy. Across the top of the spreadsheet
put the risk criteria used to prioritize the risk as described below:
1. Risk identified by System or Concept FMECA (Does the System
or Concept FMECA point toward risk in the item?). (If done)
2. Potential for safety issues (What is the degree of safety risk
associated with the item?)
3. New technology (What is the degree of new technology being
introduced with the item?)
32
RISK ANALYSIS
INTRODUCTION
INTRODUCTION
Preliminary Risk Assessment
Preliminary Risk Assessment
!
INTRODUCTION
INTRODUCTION
What is M-FMECA?
Doing FMECAs on all subsystem and components can be very
expensive and time consuming, there needs to be a way to prioritize
potential FMECA projects, to help identify which FMECAs to do.
One way to do this prioritization is Preliminary Risk Assessment.
What is M-FMECA?
4. New applications of existing technology (What is the level of
new application for existing technology with the item?)
Types of FMECA
FMECA Objectives
5. History of significant field problems (What level of field
problems has been associated with the item or similar items?)
What can FMECA be
used for?
6. Potential for important regulation issues (What level of
government regulation is associated with the item?)
Standards and Guidelines
When to perform a
FMECA
7. Mission-critical applications (To what degree can failures with
the item bring about loss of primary mission?)
The final step uses simple arithmetic to multiply the cells in each
row to obtain a risk index number for each of the subsystems or
components in the system hierarchy. This index can then be used
as input to the FMECA selection decision.
Definitions and
Examples
Preliminary Risk
Assessment
4. Supplier capability (What is the risk associated with the
supplier of the item?)
33
RISK ANALYSIS
The next step is to rank each risk criteria column for each row in
the system hierarchy on a scale of risk, such as high, medium, or
low, or 1–5. In other words, assess the risk for each item of the
component hierarchy according to the risk criteria.
!
!!!
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
34
!
INTRODUCTION
Preliminary Risk Assessment
INTRODUCTION
What is M-FMECA?
Types of FMECA
FMECA Objectives
What can FMECA be
used for?
Standards and Guidelines
When to perform a
FMECA
Definitions and
Examples
Preliminary Risk
Assessment
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
Figure shows an example of preliminary risk assessment for a bicycle project.
35
!
108!
2.2 Preparation M-FMECA
!
PREPARATION
Machinery-FMECA Methodology
Tasks done Once For All FMECA Project
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
Task done once for all
FMECA projects
Task done once for all
FMECA projects
Software Selection
Software Selection
Worksheet and Scales
Worksheet and Scales
Roles and Responsibilities
Roles and Responsibilities
System Hierarchy
System Hierarchy
Failure Information
Failure Information
Preparation Tasks For Each
New FMECA Project
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Scope of the Analysis
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Role of Suppliers
Gather and Review Relevant
Information
Gather and Review Relevant
Information
FMECA
PROCEDURE
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
!!!
1
!
!
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
PREPARATION
INTRODUCTION
PREPARATION
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
A smooth linkage between system hierarchy
FMECA worksheet
Control plans
Capacity for simultaneous users
Comprehensive search queries
Ability to link all electronic documents
Easily configurable profiles and interfaces
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Role of Suppliers
FMECA
PROCEDURE
3
!
!
!!!
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
PREPARATION
Software Selection
Worksheet and Scales
PREPARATION
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
• If the risk ranking scales are not mandated and the team has the
flexibility to establish their own risk ranking scales, there is a
simple rule to follow: use the minimum number of ranking levels
for each scale that adequately differentiates the risk criteria.
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Once agreed upon, the FMECA worksheet configuration and the risk
ranking scales should be controlled throughout the company, so that
individual FMECA teams maintain a consistent approach to FMECA
that supports company objectives.
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
(See also Example FMECA Forms in Tools section)
5
!!!
System Hierarchy
Failure Information
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Role of Suppliers
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
6
!
8
!
• Who takes the lead in selecting the FMECA projects or performing
the Preliminary Risk Assessment?
• Who carries out the FMECA preparation tasks?
• Who facilitates the FMECA team meetings?
• Who is ultimately responsible for the FMECA document?
• Who enters the information into the FMECA database?
• Who follows up on the execution of FMECA recommended
actions?
• Who communicates the high-risk issues from FMECAs to
management?
• Who in management champions the entire FMECA process and
sees to the budget, staffing and other needed resources?
• Who trains the FMECA team in the basic FMECA procedure?
FILLING
WHORKSHEET
RISK ANALYSIS
PREPARATION
PREPARATION
Tasks done Once For All FMECA Project
4 - Defining the System Hierarchy
INTRODUCTION
PREPARATION
There is no template defining the specific roles and
responsibilities for carrying out the FMECA tasks;
However It is usually a good practice to make the maintenance
engineer responsible for accomplishing Machinery FMECAs
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
It is useful for companies to document the various FMECA roles
and responsibilities in related job descriptions and work
instructions.
Scope of the Analysis
The definition of
“Customer” for a M-FMECA is the
manufacturing facility where the machinery is to be installed for
production. The manufacturing facility includes:
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
•
•
•
•
All product designs, machinery, and equipment of any kind have a
system hierarchy. It is important for the FMECA practitioner to
understand the system hierarchy.
System definition always includes the interfaces between the
subsystems.
Further definitions relating to system hierarchy follow:
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Ground Rules and Assumption
Gather and Review Relevant
Information
!
Questions often arise as to who is responsible for the various tasks
associated with FMECA projects and the nature of the responsibilities.
Tasks done Once For All FMECA Project
3 - Identifying Roles and Responsibilities
Roles and Responsibilities
Preparation Tasks For Each
New FMECA Project
4
INTRODUCTION
• The criteria for the detection scale must be reviewed and agreed
upon, clearly differentiating the likelihood of detection from very
remote to almost certain. Risk related to detection can also be
differentiated based on the timing opportunity for detection and the
type of test used for detection, in addition to likelihood of
detection.
INTRODUCTION
Task done once for all
FMECA projects
FILLING
WHORKSHEET
RISK ANALYSIS
Tasks done Once For All FMECA Project
3 - Identifying Roles and Responsibilities
!
!
PREPARATION
The criteria for the occurrence scale must be reviewed and agreed
upon, clearly differentiating the full range of anticipated failure
rates, from very low to very high, and where possible identifying
ranges of failure frequency for each occurrence level that makes
sense for the system or product being analyzed.
PREPARATION
Assemble the Correct Team
Ground Rules and Assumption
•
Tasks done Once For All FMECA Project
2 - Selecting or Modifying FMECA Worksheets and Scales
INTRODUCTION
Software Selection
The criteria for the severity scale must be reviewed and agreed
upon, clearly showing needed differentiation between safety and
regulatory risk, loss or degradation of primary and secondary
functions, and lower severity such as annoyance.
Ground Rules and Assumption
Gather and Review Relevant
Information
Task done once for all
FMECA projects
•
Make the Scope Visible
FMECA
PROCEDURE
!
At this point the FMECA team should agree on the standards to be
followed. If the FMECA standard is not mandated, Automotive Industry
Action Group (AIAG) Fourth Edition (2008) or Society of Automotive
Engineers (SAE) J1739 (2009) provide a good starting point, with a
useful description of the procedure, the worksheet columns, and risk
ranking scales.
However, it is important to tailor the worksheet columns and risk
ranking scales to company- specific applications.
Assemble the Correct Team
Gather and Review Relevant
Information
PREPARATION
2
Tasks done Once For All FMECA Project
2 - Selecting or Modifying FMECA Worksheets and Scales
FILLING
WHORKSHEET
RISK ANALYSIS
!
FILLING
WHORKSHEET
RISK ANALYSIS
PREPARATION
Having the right FMECA software can greatly improve the quality
and timing of FMECA project.
FMECA software needs to be easy to use with an intuitive user
interface, allowing the FMECA team to enter information easily, in
real time, during FMECA meetings. Some of the characteristics of
good FMECA software include:
•
•
•
•
•
•
•
FMECA software selection
Selecting or modifying FMECA scales and columns
Identifying roles and responsibilities
FMECA team training
Legal guidelines for doing FMECAs
Meeting logistics
Defining the system hierarchy
Access to failure information
Tasks done Once For All FMECA Project
1 - FMECA Software Selection
INTRODUCTION
Task done once for all
FMECA projects
1.
2.
3.
4.
5.
6.
7.
8.
Make the Scope Visible
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
PREPARATION
The following tasks need to be done once for the entire FMECA
project. Note that all of them are not mandatory, the team can decide
which tasks to perform based on the degree of complexity and the
resources allocated to the preparation of FMECA.
The advice is to follow as possible prior actions to implement a robust
FMECA.
Role of Suppliers
plant engineers
maintenance
Production
other plant support personnel
Gather and Review Relevant
Information
FMECA
PROCEDURE
7
!!!
FILLING
WHORKSHEET
RISK ANALYSIS
Hierarchy: A partitioning scheme that establishes an ordered
relationship between the
items in a system, where the items are
represented as being “above,” “below,” or “at
the same level as” one
another.
Subsystem: A system in and of itself (refer to the system definition)
contained within a higher level system. The functionality of a
subsystem contributes to the overall
functionality of the higher level
system. The scope of a subsystem’s functionality is
less than the
scope of functionality contained in the higher level system. Subsystem
definition always includes the interfaces between the components.
109!
!
!
INTRODUCTION
PREPARATION
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
PREPARATION
PREPARATION
Tasks done Once For All FMECA Project
4 - Defining the System Hierarchy
Tasks done Once For All FMECA Project
5 - Access to Failure Information
INTRODUCTION
Component: Composed of multiple parts; a clearly identified subset
of the product being designed or produced.
Part: One, two, or more pieces joined together to make a component;
these pieces comprise the lowest level of separately identifiable items
within a system and are not normally subject to disassembly without
destruction or impairment of its
designed use.
PREPARATION
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
When performing a Machinery
FMECA, a portion of the system
configuration could look like this,
with as many subsystems and
components as needed:
• System
Subsystem A
Component A.1
Component A.2
Subsystem B
Component B.1
Component B.2
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
9
!
!
!!!
Task done once for all
FMECA projects
Worksheet and Scales
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
PREPARATION
Worksheet and Scales
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
!!!
PREPARATION
PREPARATION
Preparation Tasks For Each New FMECA Project
1 – Determine the Scope of the Analysis
INTRODUCTION
PREPARATION
The next step in narrowing down the project focus is determining
the specific boundaries or scope of the individual FMECA.
Task done once for all
FMECA projects
Software Selection
Determining the scope of the analysis is an extremely important step
because clearly defined boundaries establish the issues that are to be
considered and the approach that the team will take during the
analysis. For example, the scope could be identified thus:
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
• A high-level analysis focusing generally on the entire system or
process, including interfaces and integration
Scope of the Analysis
Make the Scope Visible
Scope of the Analysis
Make the Scope Visible
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
!
!
In defining the scope of any FMECA project, it is essential to include the
interfaces between adjacent subsystems or components. This is important
because empirical data show that at least 50% of problems occur at the
interfaces between sub- systems or components
For Machinery FMECAs, the scope includes the subsystem itself, as well
as the interfaces between adjacent components.
The process of preparing the M-FMECA begins with the full
understanding of what the machinery is expected to do or not to do, in a
given environment, under stated conditions, and for a defined period of
time.
Assemble the Correct Team
• A detailed analysis focusing intensively on a specific aspect of
the system or process
Ground Rules and Assumption
Role of Suppliers
13
!!!
FILLING
WHORKSHEET
RISK ANALYSIS
These expectations may be determined from sources such as:
• the Reliability & Maintainability specification statement
• performance reports
• maintenance history
• program objectives
• federal or local regulatory requirements
PREPARATION
PREPARATION
Preparation Tasks For Each New FMECA Project
2 – Make the scope visible
Preparation Tasks For Each New FMECA Project
2 – Make the scope visible
INTRODUCTION
FMECA Block Diagram
PREPARATION
FMECA Block Diagram Examples
Task done once for all
FMECA projects
• A Block Diagram (or boundary diagram) is a visual depiction of the
entire Machinery or design to show clearly the boundaries of the
FMECA analysis (what is included and not included), the interfaces
between the items, and other information that can help to depict the
scope of the FMECA.
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Failure Information
Assemble the Correct Team
Figure: graphical depiction of the FMECA “road map.” The left portion shows
the preparation steps.
FILLING
WHORKSHEET
RISK ANALYSIS
Preparation Tasks For Each New FMECA Project
1 – Determine the Scope of the Analysis
INTRODUCTION
System Hierarchy
!!!!!!!!!!!!!!!!
Ground Rules and Assumption
!
!
Preparation Tasks For Each
New FMECA Project
16
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
FMECA
PROCEDURE
Roles and Responsibilities
!
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
11
FILLING
WHORKSHEET
RISK ANALYSIS
Software Selection
14
Roles and Responsibilities
FMECA
PROCEDURE
Worksheet and Scales
!
Software Selection
Worksheet and Scales
1. Determine the scope of the analysis
2. Make the scope visible
• FMECA Block Diagram
• Parameter Diagram (P-Diagram)
• FMECA Interface Matrix
• Functional Block Diagram
3. Assemble the correct team
4. Establish the ground rules and assumptions
5. Establish the role of suppliers
6. Gather and review relevant information
• “Gather Information Checklist”
7. Prepare FMECA software for first team meeting (if used)
8. Ready for first-meeting checklist
Gather and Review Relevant
Information
Task done once for all
FMECA projects
12
Task done once for all
FMECA projects
Gather and Review Relevant
Information
PREPARATION
!
PREPARATION
Software Selection
Roles and Responsibilities
10
INTRODUCTION
Once the one-time tasks are completed, including defining the
system hierarchy, the following are the primary preparation tasks
that should be done for each new FMECA project:
INTRODUCTION
Task done once for all
FMECA projects
1. General Lists of Failure Modes, Causes, and Failure Mechanisms.
There are publications of generic failure modes, causes, and failure
mechanisms that can be helpful to FMECA teams.
Preparation Tasks For Each New FMECA Project
!
!
PREPARATION
1. FMECA “Phrase Libraries”: (A “phrase library” is a list of
predefined descriptions that can be used to define any of the textbased record properties in an FMECA.) FMECA teams should have
easy access to all past functions, failure modes, effects, causes,
controls, and recommended actions from all previous FMECAs.
Good relational database software supports this feature.
PREPARATION
Software Selection
Roles and Responsibilities
FILLING
WHORKSHEET
RISK ANALYSIS
1. Past FMECAs: FMECA teams should have easy access to all past
company- generated FMECAs, organized by type or description, so
that teams can find past FMECAs that are similar to current
FMECA projects.
Preparation Tasks For Each New FMECA Project
INTRODUCTION
PREPARATION
FMECA teams need easy access to information that supports
identification of failure modes and causes.
The following are general sources of information about failure modes
and causes that may be useful to FMECA teams.
Preparation Tasks For Each
New FMECA Project
• Specifically, the FMECA Block Diagram is a diagram showing the
physical and logical relationships between the components in the
system or assembly and the boundary of the analysis. It identifies
relationships and dependencies between components, such as
physical connection, material exchange, energy transfer, and data
exchange, and usually shows the inputs and outputs
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
• There should be enough detail in the diagram to visually define the
scope of the analysis so the team can maintain the proper scope and
not inadvertently expand the project.
15
FMECA
PROCEDURE
!!!
FILLING
WHORKSHEET
RISK ANALYSIS
Example of FMECA block (boundary) diagram for portion of flip glass–lift gate subsystem
110!
PREPARATION
PREPARATION
Preparation Tasks For Each New FMECA Project
2 – Make the scope visible
Preparation Tasks For Each New FMECA Project
2 – Make the scope visible
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA Block Diagram Examples
Task done once for all
FMECA projects
Task done once for all
FMECA projects
Software Selection
Software Selection
Worksheet and Scales
Worksheet and Scales
Roles and Responsibilities
Roles and Responsibilities
Failure Information
Preparation Tasks For Each
New FMECA Project
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Scope of the Analysis
Make the Scope Visible
Make the Scope Visible
Assemble the Correct Team
Assemble the Correct Team
Ground Rules and Assumption
Ground Rules and Assumption
Role of Suppliers
Role of Suppliers
Gather and Review Relevant
Information
Gather and Review Relevant
Information
FMECA
PROCEDURE
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
FILLING
WHORKSHEET
RISK ANALYSIS
FMECA block diagram example: hand brake subsystem.
17
!
!
!!!
PREPARATION
PREPARATION
Task done once for all
FMECA projects
Software Selection
Software Selection
Worksheet and Scales
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
System Hierarchy
Failure Information
Failure Information
Preparation Tasks For Each
New FMECA Project
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Scope of the Analysis
Make the Scope Visible
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Interfaces can
contain up to 50% or
more of the total
failure modes
Assemble the Correct Team
Interface type:
•
Physical (P)
•
Material Exchange
(M)
•
Energy Transfer (E)
•
Data Exchange (D)
Ground Rules and Assumption
Role of Suppliers
19
!!!!
PREPARATION
PREPARATION
Preparation Tasks For Each New FMECA Project
3 – Assemble the Correct Team
PREPARATION
Software Selection
Worksheet and Scales
Worksheet and Scales
Roles and Responsibilities
Roles and Responsibilities
System Hierarchy
System Hierarchy
Failure Information
Failure Information
Preparation Tasks For Each
New FMECA Project
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Scope of the Analysis
Make the Scope Visible
Make the Scope Visible
Assemble the Correct Team
Assemble the Correct Team
Ground Rules and Assumption
Ground Rules and Assumption
Role of Suppliers
Role of Suppliers
Gather and Review Relevant
Information
Gather and Review Relevant
Information
Example of a Functional Block Diagram for a flashlight operation
21
!
!!!
INTRODUCTION
The following are suggestion, based on application experience, for
selecting the right FMECA team:
PREPARATION
Task done once for all
FMECA projects
Software Selection
1. Each of the FMECA team members should be a subjectmatter expert in his/her discipline, not a —
stand-in“ to attend
the meeting.
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
System Hierarchy
Failure Information
Make the Scope Visible
Assemble the Correct Team
Failure Information
2. It is a good idea to have between three and six team members.
Preparation Tasks For Each
New FMECA Project
3. FMECA team members need to be trained on FMECA
procedure and facilitated by someone who is trained in
facilitation techniques.
Scope of the Analysis
Make the Scope Visible
Gather and Review Relevant
Information
4. Ad hoc team members may be enlisted as needed to cover
selected issues.
Role of Suppliers
Gather and Review Relevant
Information
!
!
6. It is a good idea to have individuals on the FMECA team that
will be involved with the implementation of recommended
changes.
7. It is also a good idea to have team members who either have
decision-making authority or can provide access to people with
decision-making authority.
8. A supplier representative may participate in an original
equipment manufacturer (OEM), usually on an ad hoc basis to
provide supplier œrelated input.
FMECA
PROCEDURE
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
5. Management often has to be involved in empowering FMECA
teams to ensure attendance and support.
Assemble the Correct Team
Ground Rules and Assumption
Ground Rules and Assumption
Role of Suppliers
!
Preparation Tasks For Each New FMECA Project
3 – Assemble the Correct Team
INTRODUCTION
Scope of the Analysis
1. People have —
blind spot“. A well-defined cross functional
team minimize the errors inherent with —
blind spots“.
2. The FMECA analysis requires subject-matter experts from a
variety of disciplines to ensure incorporation of all necessary
inputs into the exercise.
3. One of the indispensable values of an FMECA is the cross
talk and synergy between subject-matter experts that occur
during the meetings. Well-defined groups can discover
things that individuals often miss.
PREPARATION
PREPARATION
Preparation Tasks For Each
New FMECA Project
There are three primary reasons for the necessity to have the correct
team when doing an FMECA:
FILLING
WHORKSHEET
RISK ANALYSIS
Preparation Tasks For Each New FMECA Project
3 – Assemble the Correct Team
Worksheet and Scales
One of the most important steps in preparing an FMECA is selecting
the right team because FMECA is a cross-functional team activity.
FMECA
PROCEDURE
FMECA
PROCEDURE
Roles and Responsibilities
24
INTRODUCTION
Functional Block Diagram
Task done once for all
FMECA projects
Software Selection
!
• Each primary (high-level) function is placed in a “block” and
visually laid out in the sequence performed. Inputs and outputs
are added for clarity.
Preparation Tasks For Each New FMECA Project
2 – Make the scope visible
Software Selection
Task done once for all
FMECA projects
22
• By making the primary functions of the equipment visible, it
allows the FMECA team members to agree on how the system
works and identify the beginning and end of system or equipment
operation.
FILLING
WHORKSHEET
RISK ANALYSIS
Task done once for all
FMECA projects
PREPARATION
!
• A Functional Block Diagram is a visual tool to describe the
operation, interrelationships, and interdependencies of the
functions of a system or equipment.
FMECA
PROCEDURE
FMECA interface matrix example: Hand Brake Subsystem
INTRODUCTION
FILLING
WHORKSHEET
RISK ANALYSIS
20
Functional Block Diagram
Gather and Review Relevant
Information
!
!
PREPARATION
!
Make the Scope Visible
Assemble the Correct Team
Role of Suppliers
18
INTRODUCTION
FMECA Interface Matrix Example
Roles and Responsibilities
Gather and Review Relevant
Information
• Interface Matrix is supplemental to the FMECA Block Diagram
and is done when the FMECA team wants to ensure that all of the
various types of interfaces are included in the analysis, missing
none.
Preparation Tasks For Each New FMECA Project
2 – Make the scope visible
Task done once for all
FMECA projects
Ground Rules and Assumption
• An interface is the point or surface where two parts or subsystems
meet, and it can take various forms. There are four primary types of
interfaces:
• physical connection
• material exchange
• energy transfer
• data exchange.
PREPARATION
Preparation Tasks For Each New FMECA Project
2 – Make the scope visible
PREPARATION
• FMECA interface matrix is a chart with the subsystems and/or
components (depending on the scope of the FMECA) on both the
vertical and horizontal axes. The chart shows which interfaces must
be considered in the analysis and the type of interface.
System Hierarchy
System Hierarchy
Failure Information
INTRODUCTION
FMECA Interface Matrix
23
!!!
FILLING
WHORKSHEET
RISK ANALYSIS
111!
PREPARATION
PREPARATION
Preparation Tasks For Each New FMECA Project
3 – Assemble the Correct Team
Preparation Tasks For Each New FMECA Project
3 – Assemble the Correct Team
INTRODUCTION
INTRODUCTION
PREPARATION
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
During the M-FMECA process, the machinery responsible engineer
is expected to actively involve representatives from all affected areas.
PREPARATION
Task done once for all
FMECA projects
Software Selection
These areas should include, but are not limited to:
• production
• manufacturing engineering
• safety,
• quality
• suppliers
• product engineering
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Ground Rules and Assumption
The M-FMECA should be a catalyst to stimulate the interchange of
ideas between activities affected and thus promotes a team approach.
Assemble the Correct Team
Ground Rules and Assumption
FMECA
PROCEDURE
In addition, for any commercial “Catalog” components, the
responsible representative from the component supplier should be
consulted as required.
FILLING
WHORKSHEET
RISK ANALYSIS
Gather and Review Relevant
Information
FMECA
PROCEDURE
!!!
25
!
!
Task done once for all
FMECA projects
Worksheet and Scales
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
PREPARATION
Preparation Tasks For Each New FMECA Project
5 – Establish the Role of Suppliers
INTRODUCTION
The following is an example of some of the ground rules and
assumptions the FMECA team may consider before commencing the
FMECA project:
Task done once for all
FMECA projects
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Software Selection
Worksheet and Scales
Roles and Responsibilities
System Hierarchy
Failure Information
Preparation Tasks For Each
New FMECA Project
Scope of the Analysis
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
Scope of the Analysis
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
• Conduct an FMECA jointly with a supplier or suppliers of critical
parts.
Make the Scope Visible
Assemble the Correct Team
Ground Rules and Assumption
• A third approach is for a representative from the OEM to review
and approve the supplier FMECA for critical parts.
Role of Suppliers
Gather and Review Relevant
Information
27
!!!
FILLING
WHORKSHEET
RISK ANALYSIS
28
PREPARATION
PREPARATION
Preparation Tasks For Each New FMECA Project
Preparation Tasks For Each New FMECA Project
6 – Gather and Review Relevant Information
6 – Gather and Review Relevant Information
!
INTRODUCTION
One of the most important steps in FMECA preparation is gathering all of
the relevant documents and information. If this step is missed or done
inadequately the FMECA meetings will be burdened with extra tasks
related to missing information.
In general, the following information is important to have available to the
FMECA team:
PREPARATION
Task done once for all
FMECA projects
Software Selection
System Hierarchy
• System Hierarchy: As discussed previouslyis a key part of FMECA
preparation and documentation.
Failure Information
Preparation Tasks For Each
New FMECA Project
• Past FMECAs: All past FMECAs for similar systems or designs or
assemblies should be available to the FMECA team. A relational
database best accomplishes this so that the FMECA information is easily
accessible to the FMECA team.
• Field History: One of the keys to successful FMECAs is using them to
avoid repeating past failures. Every company experiences some field
failures. The most successful companies do not repeat them. The
FMECA team needs to ensure that a summarized list of field failures for
similar products is easily available during the FMECA project.
29
• Technical Requirements and Specifications: Within the scope of the
FMECA project, the FMECA team requires access to all technical
requirements and specifications, including functional and performance
requirements, customer usage requirements, and operating environments.
Worksheet and Scales
Roles and Responsibilities
• Test Procedures and Test: The Machinery FMECA teams need access to
up-to-date test plans and test procedures in order to be able to assess
detection-related risk and recommend appropriate changes.
•
Detailed description of the sequence of steps in the overall operation of
the machinery.
Scope of the Analysis
Make the Scope Visible
•
Equipment literature
Role of Suppliers
•
Engineering drawings of the machinery
Gather and Review Relevant
Information
•
Machinery reliability information (estimated or actual)
Assemble the Correct Team
Ground Rules and Assumption
Role of Suppliers
Gather and Review Relevant
Information
• Invite the supplier to the FMECA team meeting when reviewing a
subsystem that includes a supplier part.
Preparation Tasks For Each
New FMECA Project
FMECA
PROCEDURE
!
!
Task done once for all
FMECA projects
Part of the preparation for an FMECA project includes determining
the role of suppliers. Root causes of important system or subsystem
failure modes can have their source within supplier parts.
Therefore, the FMECA team must consider how to involve the
supplier for critical components in the Machinery FMECA and this
may involve different approaches:
PREPARATION
1. Does the FMECA team assume the product will be manufactured or
assembled within engineering specifications?
2. What are the assumed environmental conditions?
3. What are the assumed operating profiles?
4. Will the FMECA team assume product abuse by the user? If so, to
what levels?
5. What is the definition of failure used in the FMECA?
6. How will the FMECA team use severity rankings and RPNs to
prioritize issues for corrective actions?
7. What is the process by which the FMECA team obtains approval
for FMECA recommended actions and follow-up for execution?
FILLING
WHORKSHEET
RISK ANALYSIS
PREPARATION
!
26
PREPARATION
FMECA
PROCEDURE
INTRODUCTION
FILLING
WHORKSHEET
RISK ANALYSIS
4 – Establish the Ground Rules and Assumptions
Software Selection
Roles and Responsibilities
When fully implemented, the M-FMECA discipline can be used on new,
modified, carry-over, or overhauled machinery for new applications or
environments.
Preparation Tasks For Each New FMECA Project
INTRODUCTION
PREPARATION
The team should also focus on improving the reliability, maintainability,
and durability of the machine while conducting the analysis.
Role of Suppliers
Role of Suppliers
Gather and Review Relevant
Information
Since the M-FMECA is an input to the preventive maintenance program,
and used to assist in the determination of machinery controls that will be
used, it is impossible to develop an effective M-FMECA without
Customer Maintenance and Supplier Field Service Department
represented on the team.
Make the Scope Visible
Make the Scope Visible
Assemble the Correct Team
The Machinery-FMECA is an analytical technique used primarily by a
Machinery-Responsible Engineer/Team as a means to ensure that, to the
extend possible, potential failure modes and their associated
causes/mechanisms of failure, related to the operation of the machinery,
have been considered and addressed.
FMECA
PROCEDURE
!!!
FILLING
WHORKSHEET
RISK ANALYSIS
(See also “Gather Information” and “Ready for first meeting” checklists )
30
!
112!
2.3 M-FMECA Procedure
FMECA PROCEDURE
Machinery-FMECA Methodology
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
Sequence of Steps
Sequence of Steps
Items
Items
Functions
Functions
Failure Modes
Failure Modes
Effects
Effects
Severity Ranking
Cause and Failure
Mechanisms
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Occurrence Ranking
Controls
Controls
Detection Ranking
Detection Ranking
Risk Priority Number
Risk Priority Number
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
FILLING
WHORKSHEET
1
RISK ANALYSIS
!
!
!!!
Figure: graphical depiction of the FMECA “road map.” The left portion
shows the preparation steps.
RISK ANALYSIS
Sequence of Steps
Sequence of Steps
INTRODUCTION
INTRODUCTION
FMECA
PROCEDURE
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
PREPARATION
Once the FMECA team meetings have begun, there are many ways to
proceed in doing the FMECA analysis.
There is no standard method for the sequence of steps; however, many
experienced FMECA teams use the following strategy:
FMECA
PROCEDURE
Sequence of Steps
• Each step of the FMECA analysis should be done with enough
clarity and detail to proceed to the next step in the analysis. As the
team proceeds, each step, carefully and properly articulated, makes
the subsequent step easier for the team to define.
Items
1. Enter all the primary functions for the item under analysis.
2. Beginning with the first function, enter all the failure modes and
corresponding effects, with severity rankings for the most serious effect
of each failure mode.
3. For each failure mode, enter all of the causes, with occurrence rankings
for each cause.
4. For each cause, enter prevention-type controls and detection-type
controls, with detection rankings for the best detection-type control.
5. Enter the next function and continue until all the functions are analyzed
through Risk Priority Numbers (RPNs).
6. Review the high severities and high RPNs, and develop all needed
recommended actions that will reduce risk to an acceptable level.
7. Review high-risk FMECA issues, and corresponding recommended
actions, with management and proceed to execution steps.
3
RISK ANALYSIS
!
!
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
• There is a one-to-many relationship between each of these steps.
For example, for one item, there may be many functions. For one
function, there may be many failure modes. For one failure mode,
there may be many causes. For one cause, there may be many
controls. In addition, for one cause, there may be many
recommended actions.
• It is important to understand the logical relationship between the
various elements of FMECA. (See figure in the next page)
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
!!!
4
RISK ANALYSIS
Items
Sequence of Steps
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
Sequence of Steps
Sequence of Steps
Items
The FMECA team identifies or confirms the item to be analyzed with
FMECA procedure. This will be the specific portion of the system hierarchy
established during the Preliminary Risk Assessment, or otherwise
determined by the FMECA team.
Effects
Effects
The FMECA team will need to decide how to address interfaces. From the
FMECA Block Diagram and the FMECA interface matrix, all of the
interfaces that are within the scope of the FMECA project should be clearly
identified.
Severity Ranking
Cause and Failure
Mechanisms
Severity Ranking
Cause and Failure
Mechanisms
There are two ways that the FMECA team can ensure that all the interfaces
are properly addressed:
Occurrence Ranking
Occurrence Ranking
Items
Functions
Functions
Failure Modes
Failure Modes
Controls
Controls
Detection Ranking
Detection Ranking
Risk Priority Number
Risk Priority Number
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
FILLING
WHORKSHEET
5
RISK ANALYSIS
!
!!!
• The first option is to add the interfaces to the system hierarchy directly
underneath the system (for subsystem interfaces) or directly below the
subsystem (for component interfaces).
• The second (and preferred) option is to keep the system hierarchy as it is
traditionally defined, but include each interface as a separate function,
properly describing the function of the interface.
6
RISK ANALYSIS
Functions
Functions
INTRODUCTION
INTRODUCTION
Sequence of Steps
Items
For each item under consideration, the FMECA team identifies the
primary functions.
PREPARATION
A function is “what the item or process is intended to do, usually to a
given standard of performance or requirement”.
Sequence of Steps
It is a good practice to avoid long lists of functions with narrow
differences, as it adds complexity to the analysis without adding value.
It is helpful to list functions separately when they are significantly
different.
Failure Modes
FMECA
PROCEDURE
Items
Functions
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Care should be taken to only include what the team believes to be the
primary functions, and not include requirements that are too detailed
and outside the objectives of the FMECA.
FMECA Linkages
RISK ANALYSIS
!
Thought-Starter Questions
When identifying functions the team can be asked questions such as:
•
•
•
•
•
•
“What are the primary purposes of this item?”
“What is the item supposed to do? What must the item not do?”
“What is the standard of performance?”
“What functions occur at the interfaces?”
“What safety-related functions are important for this item?”
“Any other questions that ensure all of the primary functions are
determined
Controls
Detection Ranking
Risk Priority Number
Risk Priority Number
FILLING
WHORKSHEET
!
FMECA PROCEDURE
FMECA PROCEDURE
FMECA
PROCEDURE
!
FMECA PROCEDURE
FMECA PROCEDURE
PREPARATION
!
FMECA PROCEDURE
FMECA PROCEDURE
PREPARATION
2
For Design and Machinery FMECAs, the FMECA Block Diagram and
Functional Block Diagram (if done) are both input to establishing the
functions, and make this step considerably easier.
7
FMECA Linkages
FILLING
WHORKSHEET
!!!
RISK ANALYSIS
8
!
113!
FMECA PROCEDURE
FMECA PROCEDURE
Functions
Functions
INTRODUCTION
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Requirements
PREPARATION
FMECA
PROCEDURE
Remember, for Machinery FMECAs, the function needs to include the
standard of performance or requirements.
Sequence of Steps
Items
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
Requirements are measurable characteristics of a product function or
its operation. A separate column may be included in the FMECA
worksheet for requirements or they can be included in the function
description. Functions may have multiple requirements.
In many situations, an existing document may contain detailed
information about the functions that the item or step is intended to
perform.
• Quality Function Deployment (QFD) contains design requirements
that should be considered in the FMECA.
• Technical Specifications contain product requirements that
describe the performance objectives and functions of the
machinery.
(See also checklist function type in tools section)
9
!
!
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
Examples of subsystem-level and component-level function from allterrain Hand Brake FMECA.
FILLING
WHORKSHEET
!!!
10
RISK ANALYSIS
FMECA PROCEDURE
FMECA PROCEDURE
Failure Modes
Failure Modes
INTRODUCTION
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
For each primary function, the FMECA team identifies the potential failure
modes.
Failure mode is defined as “the manner in which the item or operation
potentially fails to meet or deliver the intended function and associated
requirements.”
PREPARATION
FMECA
PROCEDURE
Functions
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Items
Functions
Each potential failure mode in an FMECA is considered independently of
any other failure mode. This enables the team to address the unique
reasons (causes of failure) for each given failure mode.
In the case of failure modes (or causes) that are not independent (in other
words, they occur in a dependent relationship) consider using Fault Tree
Analysis (FTA) to model the dependency. (More about FTA in tools
section)
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
Detection Ranking
Remember, the failure mode is not merely the antithesis of the function.
Rather, it is the manner in which an item or operation potentially fails to
meet or deliver the intended function and associated requirements.
Avoid failure mode wording that is too general such as “doesn’t work. Be
specific.
11
RISK ANALYSIS
!
!
Failure Conditions
The use of failure conditions can help identify unique failure modes.
Sequence of Steps
Items
Failure Modes
Risk Priority Number
Examples of failure conditions include:
• Premature operation
• Failure to operate at a prescribed time (complete loss of function)
• Intermittent operation
• Failure to cease operation at a prescribed time
• Loss of output during operation (reduced performance)
• Degraded operation (loss of performance over time)
• Performing an unintended or undesired function
Each function examined in relation to these failure conditions ensures
identification of all relevant failure modes.
FMECA Linkages
FILLING
WHORKSHEET
!!!
12
RISK ANALYSIS
Failure Modes
Failure Modes
INTRODUCTION
INTRODUCTION
FMECA
PROCEDURE
Sequence of Steps
Controlling the Failure Mode Description
PREPARATION
FMECA
PROCEDURE
• The verbiage of individual failure modes can be cataloged and
controlled for usage by other FMECA teams.
Sequence of Steps
Items
Items
Functions
Failure Modes
• This enables analysis and dissemination of failure information
between project teams and the entire organization.
Functions
Failure Modes
Effects
Effects
Severity Ranking
Cause and Failure
Mechanisms
• Some companies ascribe a failure mode ID number to each unique
failure mode.
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
• This allows companies to analyze common failure modes across
FMECAs and the entire company to develop broad strategies for
risk reduction.
Occurrence Ranking
Controls
Detection Ranking
Controls
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
13
RISK ANALYSIS
!
!
!!!
RISK ANALYSIS
• For each of the failure modes, the team lists the effects.
PREPARATION
FMECA
PROCEDURE
• An effect is “the consequence of the failure on the system or end
user. For Process FMECAs, the team should consider the effect of
the failure at the manufacturing or assembly level, as well as at the
system or end user.”
Effects
Occurrence Ranking
Controls
Items
Functions
Failure Modes
• Depending on the FMECA standard used, this may include local,
next level, and end effect, or it may include only the end effect.
Effects
Severity Ranking
Cause and Failure
Mechanisms
• Avoid wording effects too generally, such as “customer
dissatisfaction.” Be specific and describe the effect or consequence
on the end user.
Occurrence Ranking
Controls
Detection Ranking
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
!
!
• The verbiage of individual effects can be cataloged and controlled
for usage by other FMECA teams. This enables analysis and
dissemination of end effects across project teams and the entire
organization.
15
Thought-Starter Questions
When identifying effects the team can be asked questions such as:
Sequence of Steps
Failure Modes
Severity Ranking
Cause and Failure
Mechanisms
!
INTRODUCTION
INTRODUCTION
Functions
14
Effects
Effects
Items
Example of subsystem-level
failure mode from all-terrain
Hand Brake FMECA.
FMECA PROCEDURE
FMECA PROCEDURE
Sequence of Steps
When identifying failure modes the team can be asked questions, such as:
• “In what way could the item fail to perform its intended function?”
• “In what way could the item perform an unintended function?”
• “What could go wrong with this item?”
• “What could go wrong at the interfaces?”
• “What has gone wrong with this item in
the past?”
• “How could the item
be abused or
misused?”
Detection Ranking
FILLING
WHORKSHEET
FMECA
PROCEDURE
Though-Starter Questions
Risk Priority Number
Risk Priority Number
PREPARATION
!
FMECA PROCEDURE
FMECA PROCEDURE
PREPARATION
!
• “What is the consequence of the failure?”
• “If the item fails, what will be the consequences at the local level?
At the next higher level? At the system level? At the end user?”
• “If the item fails, what will the customer see, feel, or experience?”
• “Will the failure cause potential harm to the end users?”
• “Will the failure cause potential violation of regulations?”
• “What would a failure mean to adjacent parts/subsystems?”
• Any other questions that ensure the effects of failure are fully
understood at the local level, the next level, and system and/or end
user.
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
!!!
RISK ANALYSIS
16
!
114!
FMECA PROCEDURE
FMECA PROCEDURE
Severity Ranking
Effects
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
Sequence of Steps
Sequence of Steps
Items
Items
Functions
Functions
Failure Modes
Failure Modes
Effects
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Severity Ranking
Cause and Failure
Mechanisms
Example(of(component0level(effect(
from(all0terrain(Brake(Cable(Machinery(
FMECA
Occurrence Ranking
Controls
Controls
Detection Ranking
Detection Ranking
Risk Priority Number
Risk Priority Number
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
FILLING
WHORKSHEET
RISK ANALYSIS
Example(of(subsystem0level(effect(
from(all0terrain(Hand(Brake(Design(
FMECA
17
!
!
!!!
FMECA PROCEDURE
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Sequence of Steps
Items
Items
Functions
Functions
Failure Modes
Failure Modes
Effects
Effects
Severity Ranking
Cause and Failure
Mechanisms
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Occurrence Ranking
Detection Ranking
Risk Priority Number
Risk Priority Number
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
FILLING
WHORKSHEET
Example(of(severity(ranking
19
RISK ANALYSIS
!
!
!!!
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
Sequence of Steps
PREPARATION
FMECA
PROCEDURE
If needed, the FMECA team can develop and refer to cause
categories as “thought triggers” to help the team brainstorm specific
causes to be sure no important causes are missed.
Sequence of Steps
Items
Functions
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
!
!
Controlling the Cause Description
The verbiage of individual causes can be cataloged and controlled for
usage by other FMECA teams. This enables analysis and
dissemination of common causes across project teams and the entire
organization.
Functions
Machinery-related cause categories include:
• system interactions
• time based
• operating environment
• customer usage
• functional performance
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Cause categories are only informational, and can be tailored to
individual applications. The actual cause will need to be expanded to
ensure root cause is identified and described adequately.
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
21
!!!!
Dependent Causes
It is possible for a failure mode to result only when two or more
causes occur simultaneously, or in other words, are dependent on one
another. FMECAs typically assume that causes are independent.
There are two alternatives when the FMECA team needs to address
dependent causes.
• The first is to shift to FTA to model the dependent relationships
between causes and other events. (See also in tools section)
• The second alternative is to list the causes together in one entry in
the FMECA worksheet, using the word “and” in between the
causes.
22
RISK ANALYSIS
FMECA PROCEDURE
FMECA PROCEDURE
Causes and Failure mechanisms
Causes and Failure mechanisms
!
INTRODUCTION
Failure Mechanisms
PREPARATION
A failure mechanism is the actual physical phenomenon behind the failure
mode or the process of degradation or chain of events leading to and resulting
in a particular failure mode. The mechanism should be listed as concisely and
completely as possible.
FMECA
PROCEDURE
Sequence of Steps
Items
Items
Failure Modes
!
INTRODUCTION
Cause Categories
!
!
FMECA
PROCEDURE
20
RISK ANALYSIS
FMECA PROCEDURE
RISK ANALYSIS
PREPARATION
• There can be one or more causes, and the team should identify as
many causes as are needed to document their concerns. Causes
should be described in sufficient detail to establish the underlying
mechanisms of the cause, often called the “root” cause.
Causes and Failure mechanisms
FILLING
WHORKSHEET
INTRODUCTION
• A cause is “the specific reason for the failure, preferably found by
asking ‘why’ until the root cause is determined. For Machinery
FMECAs, the cause is the deficiency that results in the failure
mode”.
FMECA PROCEDURE
Functions
Effects
For each failure mode, the FMECA team identifies the causes.
Causes and Failure mechanisms
INTRODUCTION
Severity Ranking
Cause and Failure
Mechanisms
!
Controls
Controls
Detection Ranking
Items
18
Causes and Failure mechanisms
FMECA
PROCEDURE
Failure Modes
Properly assessed severity ranking will help ensure that high severity
and high RPN issues are addressed with corrective actions.
Severity Ranking
INTRODUCTION
Sequence of Steps
Using the agreed-upon severity scale, the team carefully reviews the
criteria column to make this judgment. If the effect is well defined, the
severity is easily established by reviewing the severity scale criteria.
FMECA PROCEDURE
PREPARATION
FMECA
PROCEDURE
Severity is “a ranking number associated with the most serious effect
for a given failure mode, based on the criteria from a severity scale. It
is a relative ranking within the scope of the specific FMECA and is
determined without regard to the likelihood of occurrence or
detection.”
RISK ANALYSIS
INTRODUCTION
PREPARATION
Having identified the most serious effect for the failure mode, the
FMECA team assesses the severity ranking. This is the severity of the
effect of the failure mode, not the severity of the failure mode itself.
For Design and Machinery FMECAs at the component level, causes can be
further defined and developed by understanding the underlying failure
mechanisms. Causes are the circumstances that induce or activate a failure
mechanism.
Wherever possible, for high-risk issues the FMECA team should define the
cause at the failure mechanism level.
Examples of failure mechanism categories include:
• Failure mechanism categories relating to metal structure components:
corrosion, cracking, deformation, fatigue, fracture, friction, yielding and
wear.
• Failure mechanism categories relating to electrical components: dielectric
breakdown, electro-migration, induced current and voltage drop.
• Failure mechanism categories relating to elastomers: abrasive wear,
compression set, extrusion, hardening, shrinking and swelling.
23
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Thought-Starter Questions
When identifying causes the team can be asked questions such as:
•
•
•
•
•
•
Occurrence Ranking
Controls
Detection Ranking
•
“How can the failure occur?”
“What could cause the item to fail in this manner?”
“What circumstances could cause the item to fail to perform
its intended function?”
“Why could the failure occur?”
“What is the mechanism of failure?”
“Are there possible system interactions, degradations,
operating environments,
For each cause identified, ask further “whys” in the direction
of isolating root cause.
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
!!!
RISK ANALYSIS
24
!
115!
FMECA PROCEDURE
FMECA PROCEDURE
Causes and Failure mechanisms
Causes and Failure mechanisms
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
Sequence of Steps
Sequence of Steps
Items
Items
Functions
Functions
Failure Modes
Failure Modes
Effects
Effects
Severity Ranking
Cause and Failure
Mechanisms
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Occurrence Ranking
Controls
Controls
Detection Ranking
Detection Ranking
Risk Priority Number
Risk Priority Number
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
Example of failure modes with associated failure mechanisms and causes.
FILLING
WHORKSHEET
25
RISK ANALYSIS
!
!
!!!
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
RISK ANALYSIS
(See also Five Whys in
tools section)
26
For each cause, the FMECA team assesses the occurrence ranking.
This is the likelihood of occurrence of the cause of the failure mode.
PREPARATION
• “Occurrence is a ranking number associated with the likelihood that
the failure mode and its associated cause will be present in the item
being analyzed within the Machinery service life”.
Sequence of Steps
FMECA
PROCEDURE
Items
Functions
Failure Modes
• Using the agreed-upon occurrence scale, the team carefully reviews
the criteria column to make this judgment. This assessment of
occurrence ranking should be as objective as possible, using past
field history of similar items, previous test results, experience with
similar systems, and other sources of information. The FMECA
team should endeavor to be as objective as possible, using the
criteria from the occurrence scale to help deter- mine the
appropriate rank.
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
• Properly assessed occurrence ranking will help ensure that risk due
to frequency of occurrence is addressed with corrective actions,
along with other high severity and high RPN issues.
27
!
!
FILLING
WHORKSHEET
!!!
Example of occurrence ranking
Controls
INTRODUCTION
INTRODUCTION
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
PREPARATION
For each cause, the FMECA team identifies the controls.
FMECA
PROCEDURE
Controls are “the methods or actions currently planned or already in place
to reduce or eliminate risk. Controls can be the methods to prevent or
detect the cause during product development, or can be actions to detect a
problem during service before it becomes catastrophic.”
Sequence of Steps
Items
Functions
Failure Modes
Most FMECA standards require two types of controls be identified (i.e.,
prevention and detection).
• Prevention-type controls describe how a cause, failure mode, or effect
in the machinery is prevented based on current or planned actions; they
are intended to reduce the likelihood that the problem will occur, and
are used as input to the occurrence ranking.
• Detection-type controls describe how a failure mode or cause detected,
based on current or planned actions, before the machinery starts
production, and are used as input to the detection ranking. Detection
controls are intended to increase the likelihood that the problem will be
detected before it reaches the end user.
29
RISK ANALYSIS
!
!
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
!!!
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
Sequence of Steps
Sequence of Steps
Items
Functions
Functions
Failure Modes
Failure Modes
Effects
Effects
Severity Ranking
Cause and Failure
Mechanisms
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Occurrence Ranking
Controls
Controls
Detection Ranking
Example of subsystem-level controls from all-terrain Hand Brake FMECA.
Risk Priority Number
Risk Priority Number
!
! When identifying detection-type controls for Machinery or Design
FMECAs, the team can be asked questions such as:
• What is already in place that could possibly detect the cause?
• What is not in place yet but is currently planned that could
possibly detect the cause?
• What tests, analyses, or other analytical or physical tasks are
already in place or currently planned that could detect the cause
before launch?
30
!
Detection Ranking
INTRODUCTION
Items
!
! When identifying prevention-type controls for Machinery or Design
FMECAs, the team can be asked questions such as:
• What is already in place that could possibly prevent the cause?
• What is not in place yet but is currently planned that could
possibly prevent the cause?
• What design guidelines, design standards, use of field lessons
learned, or other prevention-type tasks are planned or already in
place that could prevent the cause?
FMECA PROCEDURE
Controls
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
FILLING
WHORKSHEET
RISK ANALYSIS
Thought-Starter Questions
RISK ANALYSIS
FMECA PROCEDURE
Detection Ranking
!
FMECA PROCEDURE
Controls
FMECA
PROCEDURE
28
RISK ANALYSIS
FMECA PROCEDURE
PREPARATION
!
Occurrence Ranking
FMECA Linkages
FILLING
WHORKSHEET
The FMECA team
should always ask “why”
to each cause until it is
satisfied the root cause
has been deter-mined.
INTRODUCTION
INTRODUCTION
Sequence of Steps
Properly worded causes, developed to the failure mechanism level for
high-risk issues, will help to assess occurrence ranking and will help in
the process of developing effective actions to
reduce the risk associated with the
failure mode/cause.
FMECA PROCEDURE
Occurrence Ranking
FMECA
PROCEDURE
Failure mechanisms should always be included with the cause entry on
high-risk causes at the component level. It is up to the FMECA team if
they want to include failure mechanisms for other causes, such as at the
subsystem or system levels.
RISK ANALYSIS
FMECA PROCEDURE
PREPARATION
Summarize
31
!!!
RISK ANALYSIS
For each cause, the FMECA team assesses the detection ranking. This is
the likelihood that the current detection-type controls will be able to detect
the cause of the failure mode.
For Design and Machinery FMECAs, detection is the ranking number
corresponding to the likelihood that the current detection-type Controls
will detect the failure mode, cause, before it occur.
Using the agreed-upon detection scale, the team carefully reviews the
criteria column to make this judgment. Although it is possible to analyze
each control separately, this is not necessary in most applications.
A suggested approach is assuming the failure has occurred and then
assessing the capability of the detection-type or process control to detect
the failure mode or cause. If there is no detection-type control for a given
failure mode/cause, the detection ranking should be set to the highest
level.
32
!
116!
FMECA PROCEDURE
FMECA PROCEDURE
Detection Ranking
Detection Ranking
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
Sequence of Steps
Sequence of Steps
Items
Items
Functions
Functions
Failure Modes
Failure Modes
Effects
Effects
Severity Ranking
Cause and Failure
Mechanisms
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Occurrence Ranking
Controls
Controls
Detection Ranking
Detection Ranking
Risk Priority Number
Risk Priority Number
FMECA Linkages
FMECA Linkages
FILLING
WHORKSHEET
FILLING
WHORKSHEET
RISK ANALYSIS
Example of detection ranking.
!!!
33
!
!
PREPARATION
Effects
FMECA
PROCEDURE
Almost1impossible
Sequence of Steps
Very1remote
Effects
Severity Ranking
Cause and Failure
Mechanisms
Remote
Very1Low
Low
Moderate
Occurrence Ranking
Moderately1high
Controls
High
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
Very1High
Almost1certain
PREPARATION
Suggested(M*FMECA(Detection(Evaluation(Criteria
Detection
Rank
FMECA
PROCEDURE
10
Sequence of Steps
9
Items
8
Functions
7
Failure Modes
Effects
6
Severity Ranking
Cause and Failure
Mechanisms
5
4
Occurrence Ranking
Controls
3
Detection Ranking
2
Risk Priority Number
1
FMECA Linkages
Example of Machinery FMECA detection scale (integrating three types of detection risk).
35
!
!
FILLING
WHORKSHEET
!!!
Items
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
PREPARATION
There are certain limitations to using RPNs. Here are the primary ones:
FMECA
PROCEDURE
1. Subjectivity of RPN: Since the components of RPN are each
subjective ratings, the RPN value is subjective in nature. It only has
application in helping the FMECA team prioritize issues for
corrective action within a given FMECA, and cannot be used to assess
risk across different FMECAs.
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
2. Limitations of Detection: The detection scale is controversial for some
companies and practitioners, and as a result, some have chosen not to
use detection ranking at all.
3. Holes in the Scale: “Although the RPN is an integer scale, it is not
continuous. Many of the numbers in the range of 1 to 1000 cannot be
formed from the product of S, O, and D. This creates ‘holes’ in the
scale. These holes are the cause of the most serious problems in
interpreting the RPN.”[6] This is true particularly if the FMECA team
expects higher RPNs to represent higher risk in a manner that is
continuous and proportional.
37
!
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
!!!
RISK ANALYSIS
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
PREPARATION
Limitation of Using RPN
FMECA
PROCEDURE
4. Duplicate RPN Numbers: All possible products of S, O, and D
include many duplicate numbers. It is difficult to accept that failures
whose severities range from 1 (not noticeable except by the most
discerning customer) to 8 (inoperable with loss of primary function)
can be evaluated as having the same importance.
Sequence of Steps
Items
Functions
Failure Modes
Effects
For example:
Severity Ranking
Cause and Failure
Mechanisms
RPN1 =
(S=1) x (O=8) x (D=8) = 64
RPN2 = (S=8) x (O=4) x (D=2) = 64
Occurrence Ranking
Controls
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
!
!
!
!
Limitation of Using RPN
There are certain limitations to using RPNs. Here are the primary ones:
1. Subjectivity of RPN: Since the components of RPN are each subjective
ratings, the RPN value is subjective in nature. It only has application in
helping the FMECA team prioritize issues for corrective action within a
given FMECA, and cannot be used to assess risk across different
FMECAs.
2. Limitations of Detection: The detection scale is controversial for some
companies and practitioners, and as a result, some have chosen not to
use detection ranking at all.
3. Holes in the Scale: “Although the RPN is an integer scale, it is not
continuous. Many of the numbers in the range of 1 to 1000 cannot be
formed from the product of S, O, and D. This creates ‘holes’ in the
scale. These holes are the cause of the most serious problems in
interpreting the RPN.”[6] This is true particularly if the FMECA team
expects higher RPNs to represent higher risk in a manner that is
continuous and proportional.
38
!
INTRODUCTION
INTRODUCTION
Sequence of Steps
36
Risk Priority Number
Risk Priority Number
FMECA
PROCEDURE
In application, it is always necessary to separately review and address all
high severities as well as high RPNs. The reason is that high severity, but
low RPN, has the potential to result in high risk to end users and to the
company.
FMECA PROCEDURE
FMECA PROCEDURE
PREPARATION
RPN= S(severity) x O(occurrence) x D(detection)
RPN is not a perfect measure of risk. It has proven useful to a majority
of practitioners, and others have decided to use alternatives. The entire
purpose of the RPN value is to help the FMECA team prioritize issues
for corrective action within the scope of the specific FMECA project.
Risk Priority Number
INTRODUCTION
Limitation of Using RPN
PREPARATION
Functions
RPN is the product of each of the three rating scales: severity, occurrence
and detection:
FMECA PROCEDURE
Risk Priority Number
Sequence of Steps
!
RPN is “a numerical ranking of the risk of each potential failure
mode/cause, made up of the arithmetic product of the three elements:
severity of the effect, likelihood of occurrence of the cause, and
likelihood of detection of the cause.”
RISK ANALYSIS
FMECA PROCEDURE
FMECA
PROCEDURE
34
Risk Priority Number
Design'or'machinery'controls'cannot'detect'a'potential'cause'and'subsequent'failure'
or'there'are'no'design'or'machinery'controls.
Very'remote'chance'that'design'or'machinery'controls'will'detct a'potential'cause'and'
subsequent'failure'mode.
remote'change'that'design'or'machinery'controls'will'detect'a'potential'cause'and'
subsequent'failure'mode.'Machinery'control'will'provide'indication'of'failure.
Design'or'machinery'controls'do'not'prevent'the'failure'from'occurring.'Machinery'
control'will'isolate'the'cause'and'subsequent'failure'after'the'failure'has'occurred.
low'change'that'design'or'machinery'controls'will'detect'a'potential'cause'and'
subsequent'failure'mode.'Machinery'control'will'provide'an'indicator'of'imminent'
failure.
medium'change'design'controls'will'detect'a'potential'cause'and'subsequent'failure'
mode.'Machinery'control'will'prevent'imminent'failure.
moderately'high'chance'design'controls'will'detect'a'potential'cause'and'subsequent'
failure'mode.'Machinery'control'will'prevent'imminent'failure.
High'chance'that'design'controls'will'detect'a'potential'cause'and'subsequent'failure'
mode.'Machinery'control'will'prevent'imminent'failure'and'isolate'the'cause.
very'high'chance'that'design'controls'will'detect'a'potential'cause'and'subsequent'
failure'mode.'Machinery'controls'may'not'be'required.
Design'controls'almost'certain'to'detect'a'potential'cause'and'subsequent'failure'
mode.'Machinery'controls'not'required.
RISK ANALYSIS
INTRODUCTION
• Likelihood of detection by the identified controls—specifically,
what is the likelihood that the current detection-type control will
be able to discover the failure mode or its cause (remote, low,
moderate, high, etc.)?
• Timing of the opportunity for detection—specifically, what is
the timing of the current detection-type control (prior to design
freeze, post design freeze, in service, etc.)?
• Type of test used to detect the cause of the problem—what is the
quality of test method used to detect the failure mode or its
cause (degradation test, test to failure, pass/fail test, etc.)?
INTRODUCTION
INTRODUCTION
Failure Modes
The most common misunderstanding or misapplication of the detection
scale is to confuse or commingle the three types of detection risk:
FMECA PROCEDURE
Detection Ranking
Items
The detection ranking scale is the most controversial of the three risk
ranking scales (severity, occurrence, and detection).
RISK ANALYSIS
FMECA PROCEDURE
Functions
Limitation to using Detection Ranking
there is very different risk associated between these two examples.
6. RPN Thresholds: It is enticing for management to use
thresholds for RPN values and require defined action if the RPN
value exceeds the given thresh- old. In most cases, this is a
flawed approach, as it can easily become a numbers game. If
management exerts sufficient pressure, through excessive
consequences for RPN values exceeding thresholds, the FMECA
teams or suppliers can bias the RPN components (S, O, and D)
to lower the resulting RPN below the threshold. If RPN
thresholds are used at all, they should only trigger a heightened
level of review, not specifically mandated action.
Detection Ranking
Risk Priority Number
5. High Severity by Itself: High severity is high risk, regardless of the
RPN. Therefore, it is always necessary to address high severity in
addition to high RPN.
39
Limitation of Using RPN
FMECA Linkages
FILLING
WHORKSHEET
!!!
RISK ANALYSIS
40
!
117!
FMECA PROCEDURE
FMECA PROCEDURE
FMECA Linkages
Risk Priority Number
INTRODUCTION
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
Alternatives to RPN
PREPARATION
FMECA
PROCEDURE
1. S x O: The product of S×O gives a numerical rating of the combined
risk of severity and occurrence, sometimes called a Criticality
Number. If the FMECA team chooses to use S×O instead of RPN,
then the team needs to consider how to address the risk associated
with detection.
Sequence of Steps
Items
Functions
Failure Modes
Effects
2. S-O-D: Some companies use the numerical value of S-O-D. If
severity is 7, occurrence is 3, and detection is 5, then S-O-D is 735.
This avoids the “holes” in RPN, but severity by itself must still be
addressed.
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
3. S-O-D Matrix: Another interesting approach is to make a threedimensional chart based on the individual rankings for severity,
occurrence, and detection. Liken this to an xyz chart, with severity on
the x-axis, occurrence on the y-axis, and detection on the z-axis. This
approach takes into account and prioritizes for risk every
combination of S, O, and D.
41
RISK ANALYSIS
!
!
!
Detection Ranking
Risk Priority Number
FMECA Linkages
FILLING
WHORKSHEET
!!!
RISK ANALYSIS
FMECA Linkage to Design Verification Plan
A Design Verification Plan (DVP) documents the strategy that will be used
to verify and ensure that a product or system meets its design specifications
and other requirements. Each of the product requirements are listed in the
DVP along with the physical test or analytical method that will determine if
the requirement is met.
The linkage between the FMECA and the DVP plan goes two ways:
1. The FMECA team includes representation from the testing department
in order to ensure that the team considers all needed input from testing
as part of the analysis.
2. the FMECA team ensures that the DVP is impacted by the results of the
FMECA.
Specifically, when the FMECA team identifies failure modes and associated
causes that are not currently well detected in test plans or procedures, the
test plans and procedures should be updated and improved so all failure
modes of concern are detected during testing. Any changes to test
procedures or test plans should be identified as FMECA recommended
actions.
42
!
FMECA PROCEDURE
FMECA Linkages
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Sequence of Steps
Items
Functions
Failure Modes
Effects
Severity Ranking
Cause and Failure
Mechanisms
Occurrence Ranking
Controls
Detection Ranking
Risk Priority Number
Example(of(Design(Verification(Plan(for(hand(brake(subsystem.
FMECA Linkages
FILLING
WHORKSHEET
RISK ANALYSIS
!
43
!
118!
2.4 Filling worksheet M-FMECA
FILLING WORKSHEET
Machinery-FMECA Methodology
Machinery-FMECA Template
INTRODUCTION
(1)$
PREPARATION
(2)$
FMECA
PROCEDURE
(5)$
Design'responsibility………………………………..'
(3)$
Key'date………………………………………………...'
(6)$
(13)$
(9)$
FILLING
WHORKSHEET
(10)$
RISK ANALYSIS
(11)$
(14)$
(4)$
(7)$
(8)$
(17)$
(15)$
(16)$
(16)$
(19)$
(20)$
(18)$
(12)$
(22)$
(21)$
2'
1"
FILLING WORKSHEET
FILLING WORKSHEET
Machinery-FMECA Template
Machinery-FMECA Template
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
INTRODUCTION
1)  FMECA Number: Enter the M-FMECA document number, which
may be used for tracking.
2)  Machinery/System, Subsystem, or component Name and Number:
•  System M-FMECA: The focus of the System M-FMECA is to
ensure that all interfaces and interactions are covered among the
various subsystems that make up the system.
•  Subsystem M-FMECA: The focus of the Subsystem M-FMECA
is to ensure that all interfaces and interactions are covered among
the various subsystems that make up the subsystem.
•  Component M-FEMCA: Is generally an M-FMECA focused on
the sub-set of a subsystem. For example end-of-arm tooling is a
component of the robot (which is a subsystem of the underbody
welding system)
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
4)  Prepared by: Enter the name, telephone number, and the company
of the engineer responsible for preparing the M-FMECA
document.
5)  Program(s)/Plant(s): Enter the intended program(s) and plant(s)
that will use and/or be affected by the machinery being analyzed.
RISK ANALYSIS
6)  Key date: Enter the initial M-FMECA due date, which should not
exceed the scheduled engineering release date for construction.
7)  M-FMECA date: Enter the date the original M-FMECA was
compiled, and the latest revision date.
8)  Core team: List the names of the responsible individuals and
departments that have the authority to identify and/or perform
tasks.
3)  Design Responsibility: Enter the OEM, department, and group. Also
include the supplier name, if applicable.
3"
4"
FILLING WORKSHEET
FILLING WORKSHEET
Machinery-FMECA Template
Machinery-FMECA Template
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
INTRODUCTION
9)  Item/Function:
•  Enter a simple description of the step, or function, that is being
analyzed.
•  Indicate as concisely as possible the purpose/requirements of
the step, or function, being analyzed, including information
about the design (metrics/measurable) describing the system,
subsystem or component.
•  When the sequence step involves numerous functions with
different potential modes of failure, it may be desirable to list
the functions as separate elements.
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
10)  Potential Failure Mode: Is defined as the manner in which the
machinery could potentially fail to meet purpose/requirements of the
sequence step, or function, being analyzed as described in the
machinery function/requirements column.
!  A comparison of similar machinery and a review of customer
claims relating to similar machinery is a recommended starting
point.
The machinery engineer/team should be able to mode and answer the
following questions:
•  How can the machinery/sequence step fail to meet engineering
specifications?
•  What could fail to meet customer (end user, subsequent steps of
functions or field service) expectations?
Typical failure modes
5"
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Short circuit
Dirty
Binding
Open circuit
6"
Machinery-FMECA Template
11)  Potential effects of failure:
•  State clearly if the failure mode could impact noncompliance
to regulations, safety, or affects the operator.
•  The effects should always be stated in terms of what the
customer might notice or experience.
•  Any impact of the failure mode on upstream and downstream
processes should also be stated.
Typical failure effects
Machinery breakdowns
Excessive noise
Increased cycle time
Excessive effort required
Degraded out
Endangers operator/technician
Impaired performances
Partial or complete loss of function
Loss of production during
operation
Excessive vibration
Inadequate torque
Lack of repeatability
Intermittent operation
Excessive backlash
7"
!
Worn
Warped
FILLING WORKSHEET
Machinery-FMECA Template
PREPARATION
Broken
Cracked
Grounded
FILLING WORKSHEET
INTRODUCTION
Bent
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
12)  Severity (S): Is the rank associated with the most serious effect
for a given failure mode.
• 
• 
A reduction in the severity–ranking index can be effected
only through a machinery design change.
The team should agree on an evaluation criteria and ranking
system that is consistent, even if modified for an individual
system.
13)  Classification: Optional column may be used to highlight
failures with an high severity ranking or other customer
mandated usage.
8"
119!
FILLING WORKSHEET
FILLING WORKSHEET
Machinery-FMECA Template
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Machinery-FMECA Template
14)  Potential Cause(s)/Mechanism(s) of failure: Is defined as how the
failure could occur described in terms of something that can be
corrected or controlled.
•  List, to the extent possible, every failure cause assignable to each
potential failure mode.
•  If a cause is exclusive to the failure mode, then this portion of the
M-FMECA thought process is completed.
•  Many causes, however, are not mutually exclusive, and to correct
or control the cause an analysis may be required to determine
which root causes are the major contributors and which can be
most easily controlled.
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
15) Occurrence (O): Is the likelihood that a potential cause/
mechanism of failure will occur within a specific time period.
•  Preventing or controlling the cause/mechanism of failure
through a design change is the preferred way to reduce the
occurrence ranking.
•  A consistent occurrence ranking system should be used to
ensure continuity.
•  The occurrence ranking number is a relative rating
Suggested Evaluation Criteria
Typical failure causes
Inadequate or no lubrication
Corrosion
Worn locator
Material fatigue
Worn tool
Chip on locator
Contamination
Creep
Wear
Abrasion
Drift
Reliability: Is the probability that
manufacturing machinery can
perform continuously, without
failure, for a specified interval of
user’s time when operating under
stated conditions.
9"
10#
FILLING WORKSHEET
FILLING WORKSHEET
Machinery-FMECA Template
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Standard operating time: Is
the span of time the machinery is
required to run without failure. The
user’s time frame should be defined
in terms of an operating pattern that
is important to the user.
Machinery-FMECA Template
16)  Current Machinery Controls: List the prevention, detection, design
validation/verification (DV) or other activities that have been
completed or committed to that will ensure the design adequacy for the
failure mode and/or cause/mechanism under consideration.
•  Current control (e.g. design reviews, mathematical studies,
feasibility review, prototype tests) are those that have been or are
being used with the same or similar designs.
•  The team should always be focused on improving design controls.
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
17) Detection is a relative ranking, within the scope of the
individual M-FMECA.
18) In order to achieve a lower ranking, generally the planned
machinery control has to be improved.
18)  Risk Priority Number (RPN): Is the product of the Severity
(S), Occurrence (O) and Detection (D) ranking.
Types of controls
Prevention: Prevent the potential
cause/mechanism of failure or the
failure mode from occurring, or
reduce their rate of occurrence.
17)  Detection (D): Is the rank associated with the best detection
control listed in the machinery controls.
Detection: Detect the potential
cause/mechanism of failure or the
failure mode, either by analytical
or physical methods.
(S) x (O) x (D) = RPN
Within the scope of the individual M-FMECA, this value (between
1 and 1000) can be used to rank order the concerns.
The preferred approach is to firs use prevention controls, if possible.
The initial occurrence rankings will be affected by the prevention
controls provided, they are integrated as part of the design intent.
11"
12#
FILLING WORKSHEET
FILLING WORKSHEET
Machinery-FMECA Template
Machinery-FMECA Template
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
INTRODUCTION
19)  Recommended action(s): The intent of any recommended action is to
reduce rankings, in the following order: Severity, Occurrence,
Detection. The objective is to reduce risk, increase customer
satisfaction and improve the reliability, maintainability and durability
of the machine.
•  In general practice when the Severity is a ‘9’ or ‘10’, special
attention must be given to ensure that the risk is addressed through
existing design controls or preventive/corrective action(s),
regardless of the RPN
•  In all cases where the effect of an identified potential failure mode
could be a hazard to operators or technicians, preventive/
corrective actions should be taken.
•  Only a design revision can bring about a reduction in the severity
ranking.
•  Removing or controlling one or more of the causes/mechanisms of
the failure mode through design change is the preferred method to
effect a reduction in the occurrence ranking.
•  An increase in machine controls, inspection and/or preventive/
predictive maintenance will result in a reduction in detection
ranking.
13#
!
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
20)  Responsibility (for the recommended actions): Enter the
organization and individual responsible for the recommended
action and its target completion date.
21)  Action(s) taken: After the action(s) has been implemented, enter
a brief description of the actual action and effective date.
RISK ANALYSIS
22)  Revised Ratings: After the preventive/corrective action has been
identified, estimate and record the resulting severity, occurrence
and detection rankings. Calculate and record the resulting RPN.
All revised ratings should be reviewed. If further action is
considered necessary, repeat the analysis. The focus should
always be on continuous improvement.
14#
120!
2.5 Risk Analysis
Machinery FMECA Methodology
RISK ANALYSIS
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
FILLING
WHORKSHEET
FILLING
WHORKSHEET
RISK ANALYSIS
RISK ANALYSIS
Prioritize issues for
corrective action
Prioritize issues for
corrective action
Develop effective
recommended actions
Develop effective
recommended actions
Action Strategies to reduce
risk
Action Strategies to reduce
risk
Severity Ranking
Severity Ranking
Occurrence Ranking
Occurrence Ranking
Detection Ranking
Detection Ranking
FMECA Execution
Enablers
FMECA Execution
Enablers
1"
Documentation Actions
Taken
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
Documentation Actions
Taken
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
1.  The FMECA team must adequately address all High severity
problems: It means, in a scale of 1-10, addressing all 9s and
10s at minimum. The FMECA team must review and fully
understand all the high severity issues so as to address them in
its recommended actions to ensure those issues do not occur
within the life of the product.
The intention is to ensure the FMECA team takes positive and
effective action to ensure high severity issues are fully
resolved.
2.  In addiction the FMECA team needs to review and prioritize
the high RPNs There different ways to do this:
!  RPN thresholds: not recommended.
!  Begin with the highest RPN and work down the list.
!  Rank the RPNs and address an agreed-upon percentage of
total issues.
3"
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
!
PREPARATION
FMECA
PROCEDURE
If the FMECA team has chosen to use severity and Occurrence,
and not RPN, they may want to plot the severity and occurrence
rankings on a risk matrix to graphically show risk prioritization.
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
4"
Documentation Actions
Taken
RISK ANALYSIS
RISK ANALYSIS
1 - Prioritize issues for corrective action
INTRODUCTION
•  When assessing the degree of risk using the FMECA ranking scales,
it is not appropriate to compare the ratings of one team’s FMECA
with the ratings from another team.
PREPARATION
•  Even if the product or process appears to be similar, each application
is unique in terms of operating environment, customer usage, and
specific technical content.
FILLING
WHORKSHEET
•  The risk ranking scales, including RPN, are designed as a means to
prioritize issues for corrective actions within the scope of individual
FMECAs.
•  Regardless of which approach the FMECA team decides to use it is
crucial to address all high severities and all high RPNs until the level
of risk is acceptable.
FMECA
PROCEDURE
RISK ANALYSIS
!  Once we have all RPNs calculated and ordered, it can be useful to
built a Pareto-Chart (P-Chart).
A Pareto chart is a graphical overview of the process problems,
in ranking order of the most frequent, down to the least frequent,
in descending order from left to right. Thus, the Pareto diagram
illustrates the frequency of fault types. Using a Pareto, you can
decide which fault is the most serious or most frequent offender.
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
5"
6"
Documentation Actions
Taken
RISK ANALYSIS
RISK ANALYSIS
1 - Prioritize issues for corrective action
1 - Prioritize issues for corrective action
INTRODUCTION
In FMECA, P-Chart are usually used for the following:
PREPARATION
•  Comparison of RPNs between different failure modes of
the item analyzed and identification of high RPN failure
modes.
•  Comparison of total RPNs between items and identification
of high RPN items. The total RPN of each item is the
summation of RPNs of all failure modes of the item.
In either case, the team must set a cut-off value, where any failure
modes or items with an RPN above that point require further
attention.
Examples Pareto-Chart for comparison of RPNs between different
failure modes are given in figure in the next slides.
FMECA Execution
Enablers
Documentation Actions
Taken
2"
1 - Prioritize issues for corrective action
INTRODUCTION
RISK ANALYSIS
5 – Documentation actions taken
Documentation Actions
Taken
INTRODUCTION
This is the point at which the FMECA team must decide which issues
to address in the FMECA. There are two task involved:
FMECA Execution
Enablers
FILLING
WHORKSHEET
4 – FMECA Execution Enablers
RISK ANALYSIS
Documentation Actions
Taken
FMECA
PROCEDURE
3- Action strategies to reduce risk
1 - Prioritize issues for corrective action
Detection Ranking
PREPARATION
2 - Develop effective recommended actions
RISK ANALYSIS
INTRODUCTION
PREPARATION
1 - Prioritize issues for corrective action
1 - Prioritize issues for corrective action
INTRODUCTION
PREPARATION
Once the FMECA team has performed the analysis through Risk
Priority Number calculation, the important work of defining and
executing effective actions can begin.
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
7"
Documentation Actions
Taken
8"
121!
RISK ANALYSIS
RISK ANALYSIS
1 - Prioritize issues for corrective action
2 - Develop effective recommended actions
INTRODUCTION
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
FILLING
WHORKSHEET
FILLING
WHORKSHEET
RISK ANALYSIS
RISK ANALYSIS
Prioritize issues for
corrective action
Prioritize issues for
corrective action
Develop effective
recommended actions
Develop effective
recommended actions
Action Strategies to reduce
risk
Action Strategies to reduce
risk
Severity Ranking
Severity Ranking
Occurrence Ranking
Occurrence Ranking
Detection Ranking
Detection Ranking
FMECA Execution
Enablers
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
FMECA Execution
Enablers
Documentation Actions
Taken
RISK ANALYSIS
RISK ANALYSIS
3- Action strategies to reduce risk
•  Consider the full range of quality and reliability tools (See
tools section).
•  Review the corresponding engineer or manufacturing
requirements. The question needs to be asked, “Do the
engineering or manufacturing requirements need to be
changed to reflect the design or process improvements?”
•  not rely on process controls to overcome design weaknesses.
On the contrary, the focus of the Machinery FMECA team
should be on making the design more robust so that special
process controls are not required to resolve design
deficiencies.
Moreover FMECA recommended actions should be effective,
detailed, and executable. They should have management agreement
and drive design improvements.
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
!  Remember, reduce risk from high severity first, followed by risk
from high RPNs. The most effective actions mitigate the effect to a
lower severity through design changes and improve the design to
11"
make it more robust.
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
Severity Ranking
Detection Ranking
FMECA Execution
Enablers
1 - Action Strategies to reduce Severity risk
•  Design for Fail-Safe: A fail-safe design is one that, in the event of
failure, responds in a way that will cause minimal harm to other devices
or danger to personnel. Fail-safe does not mean that failure is
improbable; rather, that a system’s design mitigates any unsafe
consequences of failure. In FMECA language, fail-safe reduces the
severity of the effect to a level that is safe. Example: Laminated safety
glass for windshields prevents injury from glass shards.
•  Design for Fault-Tolerance: A fault-tolerant design is a design that
enables a system to continue operation, possibly at a reduced level (also
known as graceful degradation), rather than failing completely when
some part of the system fails. In FMECA language, fault-tolerance
reduces the severity of the effect to a level that is consistent with
performance degradation. Example: A passenger car can have “run-flat”
tires, each of which contain a solid rubber core, allowing their use even
if a tire is punctured. The punctured “run-flat” tire is effective for a
limited time at a reduced speed.
12#
Documentation Actions
Taken
RISK ANALYSIS
3- Action strategies to reduce risk
INTRODUCTION
PREPARATION
1 - Action Strategies to reduce Severity risk
•  Design for Redundancy: A redundant design provides for the
duplication of critical components of a system with the intention of
increasing reliability of the system, usually in the case of a backup or
fail-safe. This means having backup components that automatically
“kick in” should one component fail. In FMECA language, redundant
design can reduce the occurrence of system failure and reduce system
severity to a safe level.
•  Provide Early Warning: Failures that occur without warning are more
dangerous than failures with warning. Catastrophic effects can be
avoided by adding a warning device to system design. In FMECA
language, adding early warning reduces the severity of the effect,
potentially reduces the occurrence of system failure, and increases
likelihood of detection of failure mode/cause during in-service usage.
Example: A tire manufacturer adds a tire pressure monitor to alert the
driver to unsafe tire pressure.
13#
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
2 - Action Strategies to reduce Occurrence risk
•  Use Physics-of-Failure Modeling of Failure Mechanisms:
Higher risk failure mechanisms can be analytically modeled to
reduce failures and obtain an accurate advanced warning of
impending failures.
•  Use a Factor-of-Safety: One of the most effective action
strategies to prevent failures is to design in a factor-of-safety. For
structural applications, this is the ratio of the maximum stress that
a structural part or other piece of material can withstand to the
maximum stress it is anticipated to experience in the use for which
it is designed. Essentially, how much stronger the system is than it
usually needs to be for an intended load. The greater the factor-ofsafety, the lower the likelihood of structural failure. In FMECA
language, increasing the factor-of-safety reduces the frequency of
the cause of the failure mode.
14#
Documentation Actions
Taken
RISK ANALYSIS
RISK ANALYSIS
3- Action strategies to reduce risk
3- Action strategies to reduce risk
INTRODUCTION
2 - Action Strategies to reduce Occurrence risk
PREPARATION
•  Change the Way Machinery Interacts with the Environment: The FMECA
team can recommend changes in the way the product or process interacts with
the environment, which can reduce the frequency of the cause of failure.
•  Change the Way the User Interacts with the Machinery: The FMECA team
can recommend changes to the way the user or operator interacts with the
machinery, which can reduce the frequency of the cause of failure.
•  Error Proof the Manufacturing Process: The manufacturing or assembly
process can be changed so that processing errors are reduced or eliminated. In
FMECA language, error proofing a product design or a manufacturing process
reduces the frequency of the cause of the failure mode.
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
Severity Ranking
Severity Ranking
Occurrence Ranking
Occurrence Ranking
Detection Ranking
Detection Ranking
FMECA Execution
Enablers
Documentation Actions
Taken
!
FMECA
PROCEDURE
RISK ANALYSIS
INTRODUCTION
FMECA
PROCEDURE
PREPARATION
3- Action strategies to reduce risk
Documentation Actions
Taken
PREPARATION
INTRODUCTION
Occurrence Ranking
INTRODUCTION
PREPARATION
10#
Documentation Actions
Taken
2 - Develop effective recommended actions
Occurrence Ranking
Detection Ranking
In identifying recommended actions the FMECA team should:
•  take care to recommended feasible and effective actions that
will fully address the risk associated with each mode/cause.
•  consider existing controls, the relative importance
(prioritization) of the issues, as well as the cost and
effectiveness of corrective actions.
•  assign the person responsible, the due date, and other typical
project management type of information in order to be able to
execute the actions efficiently.
FMECA Execution
Enablers
9"
Documentation Actions
Taken
INTRODUCTION
The FMECA team reviews each of the high severities and each of the
high RPNs, and develops the recommended actions that will reduce
risk to an acceptable level.
There is often more than one action needed to address risk associated
with each of the failure modes and causes.
FMECA Execution
Enablers
15#
Documentation Actions
Taken
2 - Action Strategies to reduce Occurrence risk
•  Error Proof the Product Use: The operation of products or
equipment can be designed so that unsafe operation is not possible.
Example: In order to activate a metal stamping machine, two
buttons (separated by at least 3 feet) must be simultaneously
pushed.
Example: A kerosene space heater is designed to immediately
turn off if it falls over.
•  Use Statistical Process Control to Monitor and Control
Manufacturing Processes: Statistical Process Control (SPC) is the
application of statistical methods to measure and analyze the
variation in manufacturing (or other) processes, with the objective
of getting and keeping processes under control and producing conforming products. SPC can be used to maintain the consistency of
how the product is made. Properly used, SPC can significantly
reduce defects in the manufacturing process.
16#
122!
RISK ANALYSIS
RISK ANALYSIS
3- Action strategies to reduce risk
3- Action strategies to reduce risk
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
PREPARATION
•  Utilize Existing Detection-Type Controls to Increase the Likelihood
of Detection of the Cause: The FMECA team may decide to utilize
detection-type controls that already exist but were not currently used to
detect the failure mode or cause being analyzed. If selected properly, the
detection-type controls can increase the likelihood of detection of the
cause of failure.
•  Modify Existing Detection-Type Controls to Increase the Likelihood
of Detection of the Cause: The FMECA team can recommend changes
to the existing detection-type controls to increase the likelihood of
detection of the cause.
•  Develop New Detection-Type Controls to Increase the Likelihood of
Detection of the Cause: The FMECA team may decide to develop new
detection-type controls that do not currently exist. In FMECA language,
by adding the newly developed detection-type controls, the likelihood of
detecting the cause of the failure can be increased.
17#
Documentation Actions
Taken
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
Documentation Actions
Taken
INTRODUCTION
3 - Action Strategies to reduce Detection risk
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to
reduce risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
RISK ANALYSIS
4 – FMECA Execution Enablers
Thought-Starter Questions: When identifying recommended actions the team
can be asked questions such as:
1.  What can be done to reduce severity to a safe level by modifying the design?
2.  Which of the ‘Action Strategies to Reduce Severity Risk’ should be
recommended?
3.  How can the current design be made safer?
4.  If the product fails, how can the user be protected from potential harm or
injury?
5.  What can be done to reduce likelihood of occurrence to a very low level?
6.  Which of the ‘Action Strategies to Reduce Occurrence Risk’ should be
recommended?
7.  How can the current design be made more robust?
8.  What can be done to reduce likelihood of detection to a very low level?
9.  Which of the ‘Action Strategies to Reduce Detection Risk’ should be
Recommended?
10.  What tests or evaluation techniques need to be added or modified to improve
detection capability?
11.  Are there any other actions that are needed to reduce risk to an acceptable
level?
12.  If the recommended actions are implemented, will that be sufficient to
address all high severity and high RPN risk?
19#
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
Once all of the FMECA recommended actions are identified, the
FMECA team should be confident that they have identified all of the
necessary tasks and actions to reduce risk to an acceptable level.
FILLING
WHORKSHEET
The following are key elements for ensuring timely execution of
FMECA recommended actions:
RISK ANALYSIS
1.  Recommended Actions Are Well Defined: Each recommended
action should be thoroughly defined so that the end result is clear
and so that someone who is not involved in the FMECA can
understand what is being recommended.
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
FMECA Execution
Enablers
2.  Recommended Actions Include Specific Information:
•  Responsible Person
•  Action Category
•  Target Completion Date
•  Review and Approved by
20#
Documentation Actions
Taken
RISK ANALYSIS
RISK ANALYSIS
4 – FMECA Execution Enablers
4 – FMECA Execution Enablers
INTRODUCTION
3.  Recommended Actions Are Energetically Followed Up: A process needs
to be in place to follow up with the responsible person and assess
status and inform management if there are execution problems. Status
is reported back to the FMECA team who enters it into the FMECA
database. When completed, Actions Taken are recorded in the FMECA
worksheet and the team must ensure those actions reduce risk to an
acceptable level.
4.  Execution Problems Are Quickly Identified and Resolved: It is
important for the responsible person to communicate problems in
execution quickly to the FMECA team as well as to management. The
FMECA team may be able to resolve these by redefining the action or
reassigning the action item. If not, the FMECA team must elevate
execution problems quickly to management.
5.  Management Reviews All High Severity and High RPN Issues. It is
essential that management regularly review the status of FMECA
action items for both high severities and high RPNs. Feedback from
management goes back to FMECA teams for review and incorporation.
21#
PREPARATION
FMECA
PROCEDURE
FILLING
WHORKSHEET
RISK ANALYSIS
Prioritize issues for
corrective action
Develop effective
recommended actions
Action Strategies to reduce
risk
Severity Ranking
Occurrence Ranking
Detection Ranking
6.  The FMECA Team Remains Actively Involved until All FMECA
Recommended Actions Have Been Executed: The FMECA team
should meet regularly, or on an ad hoc basis, to review the status
of all FMECA recommended actions. These post-analysis
meetings have the purpose of:
•  documenting actions taken
•  ensuring proper execution
•  recommending “workarounds” if issues with execution arise
•  bringing execution problems to the attention of management
•  ensuring risk is reduced to an acceptable level
Too often omitted, this follow-up activity by the FMECA team is
critical in successful application of FMECA. In many companies, the
FMECA team ceases to meet and is dissolved once the recommended
actions are developed. The important thing is for the team to stay
vigilant and active all the way through full implementation of the
actions, particularly on the high-risk issues.
FMECA Execution
Enablers
22"
Documentation Actions
Taken
RISK ANALYSIS
RISK ANALYSIS
4 – FMECA Execution Enablers
5 – Documentation actions taken
INTRODUCTION
PREPARATION
PREPARATION
FMECA
PROCEDURE
FMECA
PROCEDURE
FILLING
WHORKSHEET
FILLING
WHORKSHEET
RISK ANALYSIS
RISK ANALYSIS
Prioritize issues for
corrective action
Prioritize issues for
corrective action
Develop effective
recommended actions
Develop effective
recommended actions
Action Strategies to reduce
risk
Action Strategies to reduce
risk
•  The FMECA team documents the specific actions taken to
implement the recommended actions. Care should be taken to
ensure that the correct actions were implemented and that the risk
is reduced to an acceptable level.
•  Once the FMECA recommended actions are implemented and
the actions taken documented in the FMECA worksheet, the
FMECA team must reassess each of the risk rankings for
severity, occurrence, and detection. This risk reassessment is very
important because it shows how well the risk associated with
each failure mode and associated cause is reduced as a result of
the specific actions from the FMECA
Severity Ranking
Severity Ranking
Occurrence Ranking
Example of recommended actions for all-terrain Hand Brake FMECA.
Detection Ranking
Detection Ranking
FMECA Execution
Enablers
FMECA Execution
Enablers
!
18#
Documentation Actions
Taken
INTRODUCTION
Documentation Actions
Taken
•  Use Improved Test Strategies, Such as Degradation Testing,
Accelerated Testing, and/or Test-To-Failure: The risk due to
inadequate controls can be reduced by changing the type of test.
Traditional pass–fail testing introduces risk by not detecting or
understanding the cause of failure. Where possible, it is important
to test to failure and use degradation testing to understand the
progression of failure. Strategies such as Highly Accelerated Life
Testing (HALT), Accelerated Life Testing (ALT), and degradation
testing can markedly improve detection risk.
RISK ANALYSIS
Documentation Actions
Taken
Occurrence Ranking
3 - Action Strategies to reduce Detection risk
3- Action strategies to reduce risk
INTRODUCTION
PREPARATION
FMECA
PROCEDURE
23#
Documentation Actions
Taken
24#
123!
3 ALLEGATO – Insight
3.1 FMECA Terminology
FMEA
Failure Mode and Effects Analysis (FMEA) is a method designed to:
• Identify and fully understand potential failure modes and their
causes, and the effects of failure on the system or end users, for
a given product or process.
• Assess the risk associated with the identified failure modes,
effects and causes, and prioritize issues for corrective action.
• Identify and carry out corrective actions to address the most
serious concerns.
By definition, FMEA is an engineering analysis done by a crossfunctional team of subject matter experts that thoroughly analyzes
product designs or manufacturing processes, early in the product
development process. Its purpose is to find and correct weaknesses
before the product gets into the hands of the customer. The primary
objective of an FMEA is to improve the design of the product or
process being analyzed.
FMECA
Failure Mode Effects and Criticality Analysis (FMECA) is similar to
FMECA, with the added step of a more formal Criticality Analysis
(CA). There are two types of CA. The first is Qualitative CA, which
uses predefined rating scales for assessing Severity (S) and
Occurrence (O) risk, and analyzes the resultant S and O values. The
second is Quantitative CA, which requires objective data to support
a criticality calculation, involving the expected failures for each
item, the mode ratio of unreliability for each potential failure mode,
and the probability that a failure of the item under consideration will
cause a system failure.
!
124!
Types of FMECAs:
System FMECA is the highest-level analysis of an entire system,
made up of various subsystems. The focus is on system-related
deficiencies, including system safety, system integration, interfaces
or interactions between subsystems or with other systems,
interactions with the surrounding environment, human interaction,
service, and other issues that could cause the overall system not to
work as intended. In System FMECA, the focus is on functions and
relationships that are unique to the system as a whole (i.e., do not
exist at lower levels). The System level FMECA includes failure
modes associated with interfaces and interactions in addition to
considering single point failures. Some practitioners separate out
human interaction and service into their own respective FMECAs.
Design FMECA focuses on product design, typically at the
subsystem or component level. The focus is on design-related
deficiencies, with emphasis on improving the design and ensuring
product operation is safe and reliable during the useful life of the
equipment. The scope of the Design FMECA includes the subsystem
or component itself, as well as the interfaces between adjacent
components. Design FMECA usually assumes the product will be
manufactured according to specifications.
Machinery FMECA is a standardized technique for evaluating
equipment and tooling during its design phase to improve the
operator safety, reliability and robustness of the machinery
Process FMECA focuses on the manufacturing or assembly
process, emphasizing how the manufacturing process can be
improved to ensure that a product is built to design requirements in a
safe manner, with minimal downtime, scrap and rework. The scope
of a Process FMECA can include manufacturing and assembly
operations, shipping, incoming parts, transporting of materials,
storage, conveyors, tool maintenance, and labeling. Process
FMECAs most often assume the design is sound.
Concept FMECA is a short version of FMECA to aid in selecting
optimum concept alternatives or to determine changes to system
design specifications. All potential failure modes and effects of each
proposed concept are considered before proceeding with actual
design.
!
125!
Software FMECA applies to software systems in which software
controls the hardware. In Software FMECA, the focus is on
identifying system weaknesses through software flow charts so that
software specifications can be made comprehensive and
unambiguous. The goals are to 1) determine whether the software is
fault tolerant with respect to hardware failures and 2) identify
missing requirements in the system specification.
Service FMECA is a type of system FMECA where the focus is on
the installation or service of equipment during operation. Sometimes
this type of FMECA is integrated with the System FMECA in which
the scope of the System FMECA includes equipment installation and
service.
Hazard Analysis is the process of examining a system throughout
its life cycle to identify inherent safety related risks. The System
Hazard Analysis focuses on identifying potential hazards associated
with the use of a product, estimating and evaluating the risks,
controlling the risks, and monitoring the effectiveness of the
controls.
Reliability-Centered Maintenance (RCM) is an analytical process
used to determine preventive maintenance (PM) requirements and
identify the need to take other actions that are warranted to ensure
safe and cost-effective operations of a system. The core of an RCM
project is an FMECA on selected manufacturing or operational
equipment, with additional unique actions that ensure the equipment
is safe and reliable in service.
FMECA worksheet definitions (in sequence of their position
in FMECA worksheets)
Item is the focus of the FMECA project. For a System FMECA this
is the system itself. For a Design FMECA, this is the subsystem or
component under analysis. For a Process FMECA, this is usually
one of the specific steps of the manufacturing or assembly process
under analysis, as represented by an Operation
Description.
Function is what the item or process is intended to do, usually to a
given standard of performance or requirement. For Design FMECAs,
!
126!
this is the primary purpose or design intent of the item. For Process
FMECAs, this is the primary purpose of the manufacturing or
assembly operation; wording should consider “Do this [operation] to
this [the part] with this [the tooling]” along with any needed
requirement. There may be many functions for each item or
operation.
Failure Mode is the manner in which the item or operation fails to
meet or deliver the intended function and its requirements.
Depending on the definition of failure established by the analysis
team, failure modes may include failure to perform a function within
defined limits, inadequate or poor performance of the function,
intermittent performance of a function, and/or performing an
unintended or undesired function. There may be many failure modes
for each function.
Effect is the consequence of the failure on the system or end user.
For Process FMECAs, the team should consider the effect of the
failure at the manufacturing or assembly level, as well as at the
system or end user. There can be more than one effect for each
failure mode. However, in most applications the FMECA team will
use the most serious of the end effects for the analysis.
Severity is a ranking number associated with the most serious effect
for a given failure mode, based on the criteria from a severity scale.
It is a relative ranking within the scope of the specific FMECA and
is determined without regard to the likelihood of occurrence or
detection.
Cause is the specific reason for the failure, preferably found by
asking “why” until the root cause is determined. For Design
FMECAs, the cause is the design deficiency that results in the failure
mode. For Process FMECAs, the cause is the manufacturing or
assembly deficiency (or source of variation) that results in the failure
mode. In most applications, particularly at the component level, the
cause is taken to the level of failure mechanism. By definition, if a
cause occurs, the corresponding failure mode occurs. There can be
many causes for each failure mode.
Occurrence is a ranking number associated with the likelihood that
the failure mode and its associated cause will be present in the item
being analyzed. For System and Design FMECAs, the occurrence
ranking considers the likelihood of occurrence during the design life
of the product. For Process FMECAs the occurrence ranking
considers the likelihood of occurrence during production. It is based
!
127!
on the criteria from the corresponding occurrence scale. The
occurrence ranking has a relative meaning rather than an absolute
value and is determined without regard to the severity or likelihood
of detection.
Controls are the methods or actions currently planned, or that are
already in place, to reduce or eliminate the risk associated with each
potential cause. Controls can be the methods to prevent or detect the
cause during product development, or actions to detect a problem
during service before it becomes catastrophic. There can be many
controls for each cause.
Prevention-type design controls describe how a cause, failure
mode, or effect in the product design is prevented based on current
or planned actions; they are intended to reduce the likelihood that the
problem will occur, and are used as input to the occurrence ranking.
Detection-type design controls describe how a failure mode or
cause in the product design is detected, based on current or planned
actions, before the product design is released to production, and are
used as input to the detection ranking. Detection controls are
intended to increase the likelihood that the problem will be detected
before it reaches the end user.
Detection is a ranking number associated with the best control from
the list of detection-type controls, based on the criteria from the
detection scale. The detection ranking considers the likelihood of
detection of the failure mode/cause, according to defined criteria.
Detection is a relative ranking within the scope of the specific
FMECA and is determined without regard to the severity or
likelihood of occurrence.
RPN is a numerical ranking of the risk of each potential failure
mode/cause, made up of the arithmetic product of the three elements:
severity of the effect, likelihood of occurrence of the cause, and
likelihood of detection of the cause.
Recommended Actions are the tasks recommended by the FMECA
team that can be performed to reduce or eliminate the risk associated
with potential cause of failure. Recommended Actions should
consider the existing controls, the relative importance (prioritization)
of the issue, and the cost and effectiveness of the corrective action.
There can be many recommended actions for each cause.
Action Taken is the specific action that is implemented to reduce
risk to an acceptable level. It should correlate to the recommended
!
128!
action and is assessed as to effectiveness by a revised severity,
occurrence, detection ranking, and corresponding revised RPN.
!
129!
3.2 Pareto Analysis
!
!
Pareto Analysis
Pareto Analysis
Content
What is for ?
What is it for?
• 
• 
Uses of this tool:
A graphical method of comparing and sorting a set of measures.
•  When you are faced with a set of measurements to compare, Pareto Analysis can be used to
prioritise these and highlight those which are most important.
Pareto Analysis uses the 80/20 Rule to select the vital few items for further action
Where could I use it?
• 
• 
•  The visual output from Pareto Analysis is useful in situations where you want to communicate
your findings and explain its significance to others.
When selecting problems, causes or solutions to take forward for further action.
When you want to visibly demonstrate priorities.
Procedure
•  Identify items to compare
•  Choose measurement units
•  Plan the measurement
•  Measure as planned
•  Plot the chart
•  Select the focus
•  Take action
•  The Pareto analysis is a fantastic tool for analyzing data, particularly for defect elimination. As
one of the keys to successful reliability engineering, defect elimination is focused on finding
the key issues affecting the equipment and solving them. This is where Pareto analysis helps to
identify those issues that have the largest impact on the equipment.
Hours Lost due to Core Cutting Defects
80
•  The chart in the next slide demonstrates an example that could have been found on a dozer
fleet. The bars display the effect of the issues from highest to lowest. These could represent
downtime hours, costs, failure events or any measurable unit.
60
40
20
•  The red line displays the cumulative percentage of each issue. This graph shows a hand full of
issues and after only 9 issue types, 80% of the
0
Burr
Risks and how to avoid them
Bent
Dent
Scratch
Shape
Example
1"
!
!!
2"
Pareto Analysis
Pareto Analysis
What is for ?
Where could I use it ?
Short of doing FMECAs on all subsystems and components, which can be very expensive and time
consuming, there needs to be a way to prioritize potential FMECA projects, to help identify which
FMECAs to do. One way to do this prioritization is Pareto Analysis that can be considered as a
variation of a Preliminary Risk Assessment
Background:
Expected Benefits:
• In the 20th Century, Joseph Juran noticed that this rule can be applied to business situations to help
focus action on ‘the vital few’ items.
• Pareto Analysis is named after the 19th Century Italian Economist, Vilfredo Pareto, who noticed
that approximately 80% of the wealth of the country was owned by 20% of the people. He also
noted that this pattern repeated itself : of the 20% rich people, 80% of the wealth that they held
was owned by 20% of these people.
•  Pareto Analysis helps you focus on the most important actions and thus leads to the best solutions and the
optimum return from your efforts and investments.
• This underlying principle is also known as The 80/20 Rule .
Uses:
How can this be applied to reliability engineering and the mining industry?
• 
• 
• 
• 
!
• The most common use of the tool is during problem analysis to find those sub-problems which,
when addressed, will return the greatest benefits.
80% of downtime are caused by 20% of component failures.
80% of maintenance spending are caused by 20% of the equipment.
80% of stock costs are caused by 20% of the stock.
80% of failures are caused by 20% of the defects or issues.
• Pareto Analysis can also be used in any general situation where you want to prioritise action. For
example, you could use it when selecting potential solutions, by comparing their cost-benefit
ratios.
• You can also use it in a team situation to show results of voting.
3"
!
Identify Items
to compare
Choose
measurement
units
• 
• 
• 
• 
• 
Plan the
measurement
Measure
as planned
• 
• 
• 
Select
the focus
4"
Pareto Analysis
Pareto Analysis
Procedure
Risks and how to avoid them
Identify the items to be analysed and charted.
These should be a single complete group that can be measured
in the same way.
For example Damaged seats
Find a measurement unit this that will lead to the highest bar
being the most important to address.
This is often a count of something.
A weighting factor may be used to ensure the highest
number is the most important.
For example, Number of defects multiplied by cost
of repair.
Determine how many items must be measured to build a representative chart.
Plan the detail of the work, including who will measure what, how, for how
long, and so on.
If possible aim for around 50 items, as this will give
a statistically repeatable chart.
If you repeat the measurement, keep all conditions
as similar as possible.
Carry out the measurement as planned.
A Check Sheet can be used to manually record measurements.
• 
Plot the results in vertical bars, sorted with the highest bar on the
left.
If there are a lot of items that would lead to a long
tail of small bars, you can combine these into an
‘others’ bar (which still should be positioned on the
right of the chart).
• 
Choose the number of bars which you will address further (this
is usually one or two).
If all bars are of a similar height, it is difficult to find
the right focus. In this case it can worth repeating the
exercise using different measurement units.
• 
Take the work to the next stage by acting on your findings.
If the bar selected is big, you can find a
further focus by breaking this down into a
sub-Pareto chart.
5"
Plot the chart
!!
Take action
!
Risks :
Steps to avoid them :
•  Selecting the wrong items, such as jumping to
conclusions rather than using proven facts.
•  Take care to start with the right problem.
•  Using measures which lead to the highest bar on the
chart indicating something that is not the most
appropriate item to address.
•  Remember that the focus is to find the most
important item, so get measurements right.
•  Assuming the people who are doing the measurement
are motivated and able to do this.
•  Educate the people who are doing the measurements
and check with their managers that they can do this
extra work.
•  Ending up with things that are too-big to address.
•  Carefully consider the effort you will need to address
the selected items. If this will be too much, then take
another step to find a lower-level focus.
•  Last-minute changes that are based on intuition rather
than measurements and known facts.
!!
•  Be very careful when taking intuitive leaps. It is
often better to trust a process which can later be
verified.
15 July 2010, Slide 6
Pareto Analysis
Pareto Analysis
Example
Example
!
!
1.#Iden(fy#Items#
Item to measure: Core cutting defects
3.#Plan#the#measurement#
2.#Choose#measurement#units#
Measurement alternatives:
• 
• 
• 
• 
Type of defect
Location of defect
Customer impact of defect
Hours lost due to defect
5.#Plot#the#chart#
4.#Measure#as#planned#
Hours Lost due to Core Cutting Defects
Core Cutting Defect Hours
Type of Defect
Shape
80
Hours Lost
2
Burr
65
Dent
30
Scratch
5
Bent
53
Total
155
60
40
20
0
Burr
Bent
Dent
Scratch
Shape
6.#Select#the#focus#
7.#Take#ac(on#
7"
!
8"
130!
3.3 Fault Tree Analysis
!
FAULT TREE ANALYSIS (FTA)
FAULT TREE ANALYSIS (FTA)
FTA and FMECA
What is a Fault Tree Analysis ?
What is a Fault Tree
Analysis
FTA and FMECA
Events and Gates
FTA Glossary
FTA Procedure
Handbooks and
Standards
Benefits and limitations
What is a Fault Tree
Analysis
•  Fault Tree Analysis (FTA) is a type of failure analysis in which an
undesired state of a system is analyzed using Boolean logic to
combine a series of lower level events.
FTA and FMECA
•  This analysis method is used mainly to quantitatively determine the
probability of a complex safety hazard in order to develop actions
to mitigate or eliminate the hazard.
Events and Gates
FTA Glossary
•  It is a top-down graphical model of the pathways and unique
relationships within a system that can lead to an unwanted top-level
event.
FTA Procedure
Handbooks and
Standards
•  The pathways connect contributory events and conditions using
standard logic symbols. The unwanted event can be a failure,
undesired event, or unintended event.
•  FTA is best applied when there is a large threat of loss, or other
high-risk situation, with numerous potential contributors to the
event.
!
Benefits and limitations
FTA and FMECA
Events and Gates
FTA Glossary
FTA Procedure
Handbooks and
Standards
Benefits and limitations
!  An event is a graphical and mathematical representation of a fault or
other unwanted occurrence. An event in a fault tree can be associated
with a probability of occurrence (or a distribution function). There are
many types of events used in FTA, the most common are:
•  top-level event
•  intermediate event
•  basic event.
!  A gate is a logic symbol that interconnects contributory events and
conditions in a fault tree diagram. The most common gates are:
•  The AND gate, in which the output fault occurs if all of the input
faults occur
•  The OR gate, in which the output fault occurs if at least one of the
input faults occurs.
•  The voting OR gate, in which the output event occurs if a certain
number of the input events occur
FAULT TREE ANALYSIS (FTA)
EVENTS and GATES
What is a Fault Tree
Analysis
FTA and FMECA
Events and Gates
FTA Glossary
FTA Procedure
Handbooks and
Standards
Benefits and limitations
FAULT TREE ANALYSIS (FTA)
FAULT TREE ANALYSIS (FTA)
EVENTS and GATES
FTA Glossary
What is a Fault Tree
Analysis
What is a Fault Tree
Analysis
FTA and FMECA
FTA and FMECA
Events and Gates
Events and Gates
FTA Glossary
FTA Glossary
FTA Procedure
FTA Procedure
Handbooks and
Standards
Handbooks and
Standards
Benefits and limitations
Benefits and limitations
FAULT TREE ANALYSIS (FTA)
FTA and FMECA
Events and Gates
FTA Glossary
FTA Procedure
Handbooks and
Standards
Benefits and limitations
!
!  External Event: An event that is normally expected either to
occur or not to occur. In general, these events have a fixed
probability of 0 or 1.
!  Failure: The inability of an item to perform its required
function within previously specified limits.
!  Fault: An anomaly in the functional operation of an
equipment or system.
!  Fault Tree Analysis: A graphic “model” of the pathways
within a system that can lead to a foreseeable, undesirable
loss event.
!  Gate: Logic symbol used in FTA that represents the
relationship between fault inputs and outputs. There are many
types of gates that are used in FTA, the most common being
AND gates and OR gates.
!  Inhibit Gate: An inhibit gate output fault occurs if all input
events occur and an additional event occurs.
The following definitions may be useful for application of Fault
Tree Analysis:
!  AND Gate: An AND gate output fault occurs if all of the input
faults occur.
!  Basic Event: An initiating fault that requires no further
development.
!  Conditioning Event: A specific condition or restriction that
can apply to any gate.
!  Cut Set: A set of basic events whose occurrence ensures that
the top event occurs. A cut set is said to be minimal if the set
cannot be reduced without losing its status as a cut set.
!  Event: A graphical and mathematical representation of a fault
or other unwanted occurrence. There are many types of events
that are used in FTA, the most common being top-level event,
intermediate event, and basic event.
FAULT TREE ANALYSIS (FTA)
FTA Glossary
What is a Fault Tree
Analysis
1.  The FMECA team is analyzing a complex failure mode with
many causes and would like a visual tool that graphically shows
the complex set of causes.
2.  Two or more causes of a given failure mode are not unique, but
rather occur in tandem (AND gates); and in order to account for
the logic of these path- ways, an FTA would be useful.
3.  The FMECA team would like to understand the probability of a
high-level unwanted event occurring.
!
EVENTS and GATES
Events and gates are symbols that represent the logic of the analysis. They
do not always correlate to component parts of the system being analyzed.
In the context of FMECA projects, FTA can be a useful additional
analysis when- ever one or more of the following circumstances
arise:
!!!
FAULT TREE ANALYSIS (FTA)
What is a Fault Tree
Analysis
FTA should be used in addiction to FMECA when it is necessary to
model or understand the interconnected relationship between causes,
failure modes, or effects. The unwanted event can be either a failure
mode or an effect.
FTA Glossary
What is a Fault Tree
Analysis
FTA and FMECA
Events and Gates
FTA Glossary
FTA Procedure
Handbooks and
Standards
Benefits and limitations
!  Intermediate Event: A fault that occurs because of one or more
antecedent causes acting through logic gates.
!  OR Gate: An OR gate output fault occurs if at least one of the
input faults occurs.
!  Path Set: A set of basic events whose nonoccurrence
(simultaneously) ensures that the top event does not occur. A path
set is said to be minimal if the set cannot be reduced without
losing its status as a path set.
!  Priority AND Gate: A priority AND gate output fault occurs if all
input events occur in a specific sequence.
!  Top-Level Event: The highest-level focus of the FTA. It is the
unwanted occurrence that represents the outcome of the entire
graphical model of the FTA. All of the other gates and sub-events
lead up to the top-level event.
!  Voting OR Gate: A voting OR gate output fault occurs if a certain
number of the input events occur.
131!
FAULT TREE ANALYSIS (FTA)
FAULT TREE ANALYSIS (FTA)
FTA Procedure
What is a Fault Tree
Analysis
FTA and FMECA
Events and Gates
FTA Glossary
FTA Procedure
Handbooks and
Standards
Benefits and limitations
1 - Define the undesired top event to study
FTA Procedure
What is a Fault Tree
Analysis
An FTA always begins with an already identified unwanted
event in which there is a large threat of loss or other high-risk
situation and numerous potential contributors to the event.
FTA and FMECA
Careful choice of the top event is important to the success of
the analysis. If it is too general, the analysis becomes
unmanageable; if it is too specific, the analysis does not
provide a sufficiently broad view of the system.
FTA Glossary
Fault tree analysis can be an expensive and time-consuming
exercise and its cost must be measured against the cost
associated with the occurrence of the relevant undesired
event.
FTA Procedure
Handbooks and
Standards
FTA and FMECA
Events and Gates
After identifying the top-level undesired event and having
analyzed the system so that all the primary contributors and
causes are known, including their probabilities, the fault tree
can be constructed.
FTA Glossary
FTA Procedure
Handbooks and
Standards
Benefits and limitations
For complex systems, this may have to be done in layers,
with each subsequent layer going deeper into the system. If
the probabilities of various contributors are known at this
point, they should be noted.
The appropriate subject-matter experts need to be consulted
in order to fully understand the overall system that affects the
event under consideration.
Benefits and limitations
FAULT TREE ANALYSIS (FTA)
FTA Procedure
FTA Procedure
3 – Construct the Fault Tree
Once the undesired event is defined, the next step is to
identify the underlying contributors and causes.
Events and Gates
FAULT TREE ANALYSIS (FTA)
What is a Fault Tree
Analysis
2 – Obtain an understanding of the system
What is a Fault Tree
Analysis
FTA and FMECA
Events and Gates
FTA Glossary
The contributors and causes of the event are logically
connected through the various gates and sub-events
according to FTA procedure. This construction process goes
deeper and deeper into sub-events until root causes are
documented.
Good FTA software will facilitate construction of the FTA
and help with connecting proper and logical pathways.
FTA Procedure
Handbooks and
Standards
Benefits and limitations
FTA example for top event (bicycle doesn’t stop in required distance).
FAULT TREE ANALYSIS (FTA)
FAULT TREE ANALYSIS (FTA)
FTA Procedure
What is a Fault Tree
Analysis
FTA and FMECA
Events and Gates
FTA Glossary
FTA Procedure
Handbooks and
Standards
Benefits and limitations
4 – Evaluate the Fault Tree
Once constructed properly for a specific undesired event, the
fault tree can be evaluated and analyzed to discover the
overall probability of the top event.
Various “what if” scenarios can be developed and analyzed
for system improvement.
Good FTA software can be useful in order to analyze
mathematically the fault tree with all of its Boolean logic and
numerous pathways.
5 – Control the Risk Identifies
The FTA should be used to support the identification and
execution of specific strategies to reduce the probability and
associated risk of an unwanted event. Changes to the system
configuration can be reviewed and analyzed, along with
associated cost and effectiveness.
FTA Handbook and Standards
What is a Fault Tree
Analysis
FTA and FMECA
Events and Gates
FTA Glossary
FTA Procedure
Handbooks and
Standards
Benefits and limitations
FAULT TREE ANALYSIS (FTA)
FTA and FMECA
Events and Gates
FTA Glossary
FTA Procedure
Handbooks and
Standards
Benefits and
limitations
!
•  U.S. Nuclear Regulatory Commission Fault Tree Handbook,
NUREG-0492, published January 1981
•  IEC International Standard Fault Tree Analysis (FTA), IEC
61025 Edition 2.0 2006-12
•  FAA System Safety Handbook, Chapter 9: Analysis
Techniques, Dec 30, 2000
FAULT TREE ANALYSIS (FTA)
Benefits and Limitations
What is a Fault Tree
Analysis
•  NASA Fault Tree Handbook with Aerospace Applications,
version 1.1, Prepared for NASA Office of Safety and Mission
Assurance, NASA Headquarters Washington, DC 20546,
published August 2002
Benefits and Limitations
What is a Fault Tree
Analysis
Properly done, FTA will provide the following benefits:
1.  Graphically and mathematically, show the risk of an
unwanted event, along with the complex relationships of
primary contributors.
2.  Identifythesetofbasiceventswhoseoccurrencewillbringaboutt
heunwantetop event.
3.  Serve as evidence of “due care” in the development of
products or processes.
4.  Provide input to various related activities, for example, test
procedures, troubleshooting manuals, and maintenance
procedures.
FTA has certain limitations to keep in mind:
FTA and FMECA
Events and Gates
FTA Glossary
FTA Procedure
Handbooks and
Standards
1.  FTA is a labor-intensive activity, and therefore the time
taken to do the analysis must be balanced with the benefits
derived from the activity.
2.  There is a high level of expertise needed to perform the
analysis.
3.  since probability data are based on estimations and
predictions of the frequency of faults and failures, care must
be taken to interpret the results with respect to any potential
errors in the input data.
Benefits and
limitations
132!
3.4 FMECA Form
Example FMECA Forms Depending on the FMECA standard selected
and individual company policy and needs, there are many different forms
available for FMECA applications. Users are encouraged to take the time
to study different forms, including the benefits and limitations for each,
and then develop the forms/columns that make sense for one’s own
unique applications.
FMECA Header Part of establishing the content and format of the
FMECA work-sheet is to agree on the header information that will be
associated with each FMECA. The FMECA header typically includes the
following information:
•
FMECA type (such as system, design, process, etc.)
•
FMECA description
•
FMECA number
•
Start date, finish date, revision date
•
Information about the project (such as model year, description of the
higher level system, etc.)
•
Design or process owner (the person who is responsible for the design
or process)
•
Primary approval (if applicable)
•
Core team/facilitator
•
User-defined fields (company-specific information relevant to the
FMEA)
FMECA Item Properties Each FMECA is performed on an item, which is
the focus of the FMECA project. For a Design FMECA, this is the
subsystem or component under analysis. For a Machinery FMECA, this is
usually the Machine or a component under analysis. There are properties
associated with each item, and the team needs to agree on the properties,
such as:
•
Item or operation name
•
Item or operation description
•
Part number or operation number
•
Information about the reliability of item or operation
•
Any other information that describes the item or operation being
!
133!
analyzed
FMECA Attachments In addition, the company or the FMECA team
should agree on the specific information that will be electronically
attached to the FMECA and easily accessible to the FMECA team.
Typical attachments include:
•
Ongoing record of meeting attendance with names and dates
•
Preliminary Risk Assessment
•
Current test plans or Process Control Plans
•
Diagrams (such as FMECA Block Diagram, Parameter Diagram [PDiagram], Functional Block Diagram, FMECA Interface Matrix,
etc.)
•
Ground rules and assumptions
•
“Gather information” documents (such as drawings, schematics,
engineering specifications, field history, etc.)
•
Other documents and information that the company or team believes
should be attached and accessible
FMECA Forms The following FMECA worksheet forms are examples
from a variety of industry applications. They include forms for Design
FMECAs and Machinery FMECAs. They do not follow any given
FMECA standard, and can be tailored to the unique industry application.
Each individual form gives a brief explanation of the rationale for the
form.
1. This is the basis FMECA form, whit prevention-type Controls in the
same column as the detection-type controls. If this form is used, it is
recommended to note next to each Control what type t is (P or D).
Note that it is recommended to place each “item” in a separate column
from the corresponding “Function(s)”
!
134!
2. This is a basic FMECA form, with the Prevention-type Controls in a
separate column from the Detection-type Controls, which is preferred
for visual clarity. Note that it is recommended to place each “Item” in
a separate column from the corresponding “Function(s).”
3. This is a simple FMECA form, with the added “Requirements”
column. This added column aids in identifying the “standard of
performance” for each Function. Note that it is recommended to place
each “Item” in a separate column from the corresponding
“Function(s).”
4. In this FMECA form, the Prevention-type Design Controls are shifted
to just before the Occurrence column in order to aid in Occurrence
ranking.
!
135!
!
136!
3.5 Criticality Analysis
!
!
!
CRITICALITY ANALYSIS
CRITICALITY ANALYSIS
1 – Quantitative Criticality Analysis
Criticality Analysis: an objective procedure by which each potential failure mode is
ranked according to the combined influence of its severity and probability of
occurrence, and each item has an assigned criticality number.
There are two common reasons that drive an organization to use a Criticality Analysis
instead of RPNs ranking discussed in “methodology section”.
•  The most common reason occurs when government or a customer mandates a
FMECA. When mandated, it is usually required to use one of the standards such as
Military Standard (MIL-STD) 1629A or Society of Automotive Engineers (SAE)
ARP5580 as the standard for application.
•  A second reason is the organization may wish to benefit from the more detailed riskranking information from the Criticality Analysis, provided there is sufficient
objective failure data and time available to perform the more rigorous calculations.
Quantitative Criticality Analysis is a series of calculations to rank items and failure
modes according to a formula covered below. To use Quantitative Criticality Analysis
to evaluate risk and prioritize corrective actions:
1.  Calculate the Expected Failures for Each Item (λ):
This is the number of failures estimated to occur based on the reliability/
unreliability of the item at a given time. Reliability is the probability that an item
will perform a required function without failure under stated conditions for a
stated period of time.
The “time (t)” for the calculation is most often the target or useful life of the item.
Care must be taken to ensure calculations for reliability/unreliability and expected
failures are based on correct failure distributions.
With an exponential distribution, expected failures is calculated by multiplying
the failure rate by the time (λ*t), but it is estimated differently for other
distributions.
CRITICALITY ANALYSIS
CRITICALITY ANALYSIS
1 – Quantitative Criticality Analysis
1 – Quantitative Criticality Analysis
2.  Identify the Mode Ratio of Unreliability (i.e. one minus reliability) for Each
Potential Failure Mode (α):
3.  Rate the Probability of Loss That Will Result from Each Failure Mode That Will Occur:
This represents the percentage of all failures for the item that will be due to the
failure mode under consideration. The total percentage assigned to all modes must
be equal to 100%.
This is the probability that a failure of the item under analysis will cause a system
failure (β).
The failure mode ratio of unreliability can be based on:
•  reliability growth testing data for the current design
•  field data and/or test data from a similar design
•  engineering judgment (“best guess”)
•  apportionment libraries such as MIL-HDBK-338B.
(i.e. one minus reliability)
The values represent the analyst’s judgment as too the conditional probability the
loss will occur and should be quantified in general accordance with the following:
• 
• 
• 
• 
Actual Loss:
Probable Loss:
Possible Loss:
No effect:
β=1
0,1 < β < 1
0 < β < 0,1
β=0
h"ps://uk.promis.eu/
CRITICALITY ANALYSIS
CRITICALITY ANALYSIS
1 – Quantitative Criticality Analysis
1 – Quantitative Criticality Analysis
Example Bicycle Brake Pad (figure in next slide)
5.  Calculate the Item Criticality for Each Item.
This is the sum of the mode criticalities for each failure mode identified for the item.
It can be calculated as:
!
!! = !
!∗!∗!∗!
!!!
Cr = Criticality number for the item
β = Probability of Loss
α = Mode Ratio of Unreliability
λ = Expected Failures
t = operation time
n = The failure modes in the items
j = Last failure mode in the items
h"ps://uk.promis.eu/
!!
Item: bicycle brake pad
Assumptions for this example: time frame = 5 years; customer usage for high end user = 3 h/day
or 5475 hours over the life of the brake pad. Assumed failure rate = 0.0001 failures/hour.
1.  Calculate the expected failures for the brake pad at 5 years. Based on assumptions, the
number of failures at 5 years is 0.548 (5475 hours multiplied by 0.0001 failures/hour)
2.  Identify the portion of the item’s unreliability (in terms of expected failures) attributed to
each potential failure mode. In this example, there are two failure modes: excessive wear
(85%) and cracking (15%).
3.  Rate the probability of loss (or severity) that will result from each failure mode that will
occur. In this example, the probability of loss of the system due to excessive wear is 75%
and due to cracking is 15%.
4.  Calculate the criticality for each potential failure mode by obtaining the product of the three
factors:
Mode Criticality for excessive wear = 0.548 × 0.85 × 0.75 = 0.349
Mode Criticality for cracking = 0.548 × 0.15 × 0.15 = 0.012.
5.  Calculate the criticality for each item by obtaining the sum of the criticalities for each
failure mode identified for the item:
Item Criticality for the brake pad = 0.349 + 0.012 = 0.361.
h"ps://uk.promis.eu/
CRITICALITY ANALYSIS
CRITICALITY ANALYSIS
1 – Quantitative Criticality Analysis
2 – Qualitative Criticality Analysis
This type of CA does not involve the same rigorous calculations as Quantitative CA.
To use Qualitative Analysis to evaluate risk and prioritize corrective actions:
1.  Rate the severity of the potential effects of failure. The severity ranking is
determined using the unique severity scale for FMECA.
2.  Rate the likelihood of occurrence for each potential failure mode. The occurrence
ranking is determined using the unique occurrence scale for FMECA.
3.  Compare failure modes using a criticality matrix. The criticality matrix identifies
severity on the horizontal axis and occurrence on the vertical axis.
Example of Quantitative Criticality Analysis on a bicycle brake pad.
h"ps://uk.promis.eu/
!
137!
CRITICALITY ANALYSIS
CRITICALITY ANALYSIS
2 – Qualitative Criticality Analysis
1 - The scale utilized to assign severity classification from MIL-STD 1629A follows:
severity(classifica-on((MIL4STD(1629A)(
Category)
Name)
2 – Qualitative Criticality Analysis
2 - The scale utilized to assign failure probability from MIL-STD 1629A follows:
Failure(Probability(((MIL2STD(1629A)(
Level%
)Criteria)
Catastrophic+
Descrip/on%
A(high(probability(of(occurrence(during(the(item(opera7ng(7me(interval.(
A
I
Name%
Frequent( Frequent(may(be(defined(as(a(single(failure(mode(probability(greater(than(0.20(
of(the(overall(probability(of(failure(during(the(item(opera7ng(7me(interval.((
A+failure+that+may+cause+death+or+system+loss+
II
Cri4cal+
A+failure+that+may+cause+severe+injury,+major+property+
damage,+or+major+system+damage+which+will+result+in+
mission+loss++
B
Reasonably(
Probable(
Occasional(
Marginal+
A+failure+that+may+cause+minor+injury,+minor+property+
damage,+or+minor+system+damage+which+will+result+in+
delay+or+loss+of+availability+or+mission+degrada4on++
C
III
D
Remote(
IV
Minor+
A+failure+that+is+not+serious+enough+to+cause+injury,+
property+damage,+or+system+damage,+but+will+result+in+
unscheduled+maintenance+or+repair.++
E
Extremely(
Unlikely(
A(moderate(probability(of(occurrence(during(the(item(opera7ng(7me(interval.(
Reasonably(probable(may(be(defined(as(a(single(failure(mode(probability(of(
occurrence(which(is(more(than(0.10(but(less(than(0.20(of(the(overall(probability(
of(failure(during(the(item(opera7ng(7me.(
An(occasional(probability(of(occurrence(during(item(opera7ng(7me(interval.(
Occasional(probability(may(be(defined(as(a(single(failure(mode(probability(of(
occurrence(which(is(more(than(0.01(but(less(than(0.10(of(the(overall(probability(
of(failure(during(the(item(opera7ng(7me.((
An(unlikely(probability(of(occurrence(during(item(opera7ng(7me(interval.(
Remote(probability(may(be(defined(as(a(single(failure(mode(probability(of(
occurrence(which(is(more(than(0.001(but(less(than(0.01(of(the(overall(
probability(of(failure(during(the(item(opera7ng(7me.(
A(failure(whose(probability(of(occurrence(is(essen7ally(zero(during(item(
opera7ng(7me(interval.(Extremely(unlikely(may(be(defined(as(a(single(failure(
mode(probability(of(occurrence(which(is(less(than(0.001(of(the(overall(
probability(of(failure(during(the(item(opera7ng(7me.((
CRITICALITY ANALYSIS
CRITICALITY ANALYSIS
2 – Qualitative Criticality Analysis
2 – Qualitative Criticality Analysis
3.  It can be useful to graphically display the risk associated with severity and
occurrence. This graphical depiction is called a criticality matrix (CA). The CA
identifies severity on the horizontal axis and occurrence on the vertical axis.
Once we have the criticality matrix
completed, it is possible to divide
Ranking in different classes in order to
be analyzed.
Action not required
Action optional !
Action required
Example of Qualitative Criticality Analysis on a bicycle brake pad.
!
138!
3.6 FMECA Quality Audit
FMECA Qualitative Audit Procedure
FMECA Qualitative Audit Procedure
Much is learned by observing the mistakes companies have made in doing FMECAs.
This chapter outlines the most common FMECA mistakes and describes how to avoid
them. FMECA Quality Objectives are described, along with an effective FMECA audit
procedure.
The FMECA quality audit procedure is an essential part of ensuring good quality
FMECAs. FMECA quality audits are in-person audits of completed (or nearly
completed) FMECAs, done with the FMECA facilitator and the FMECA core team
present.
Below are the most common FMECA mistakes and their corresponding quality
objectives, including examples for each mistake, and guidelines on how to audit each
FMECA Quality Objective. The FMECA team should review these Quality Objectives
as needed to ensure they are met before the FMEA is considered complete.
•  Each of the ten FMECA Quality objectives have a corresponding “How to audit”
recommendation.
•  Each Quality Objective is evaluated for how well is achieved.
•  The results of the audit provide valuable feedback to improve future FMECAs.
•  Action items from the FMECA quality audit should be documented and pursued to
improve the overall FMECA process.
•  Don’t expect to achieve all ten FMECA quality objectives instantly. Rather work to
maintain steady improvement.
2"
FMECA Quality Audit Procedure
FMECA Quality Audit Procedure
FMECA 10 Quality Objectives
FMECA 10 Quality Objectives
1.  Design improvements: The FMECA drives product design improvements as the primary
objective.
2.  High-Risk failure modes: The FMECA addresses all high-risk failure modes with effective
and executable action plans
3.  DVP: The Design Verification Plan considers the failure modes from the FMECA.
4.  Interfaces: The FMECA scope includes integration and interface failure modes in both
block diagram and analysis.
5.  Lessons Learned: The FMECA considers all major “lessons learned” (such as highwarranty, campaigns, etc.) as input to failure mode identification.
6.  Timing: The FMECA is completed during the “window of opportunity” whence it can most
effectively influence the product design.
7.  Level of details: The FMECA provides the correct level of detail in order to get to root
causes and effective actions.
8.  Team: The right people are adequately trained in the procedure and participate on the
FMECA team throughout the analysis.
9.  Documentation: The FMECA document is completely filled out “by the book” including
“Action taken” and final risk assessment
10.  Time usage: Time spent by the FMECA team is an effective and efficient use of time with a
value added results
2. 
1.  Design Improvements: The FMECA drives product design improvements as the
primary objective.
Example: A company that developed products under government regulation requested
assistance in reviewing their FMECA process in order to improve the quality of the
results. A review of actual FMECAs showed there were few recommended actions. When
asked why so few recommended actions were included in the FMECAs, the answer was
high Risk Priority Numbers (RPNs) and corresponding recommended actions often
triggered negative responses from the government, and they needed to pass regulations.
The company was informed the way they were doing FMECAs was a waste of time. The
company changed the process to perform proper FMECAs with the objective to improve
the safety and design of the equipment. Then, a document was prepared to verify that the
equipment was fully safe and reliable, and to satisfy government regulatory requirements.
How To Audit:
Look at recommended actions and observe whether or not most of them drive design
improvements.
Talk with the team to ensure focus was on improvements to design.
FMECA Quality Audit Procedure
FMECA Quality Audit Procedure
FMECA 10 Quality Objectives
FMECA 10 Quality Objectives
High-Risk Failure Mode: The FMECA addresses all high-risk failure modes with
effective and executable action plans.
3. 
How To Audit:
Review the recommended actions to see if there are improvements to the Design
Verification Plans based on risk associated with current detection controls. Talk with the
team to determine if they had adequate representation from testing and if the FMECA
benefited from the testing experience, and to learn whether the test regimens were
improved if the current detection controls were not adequate.
How To Audit:
Review high severity and high RPN issues to see if the corresponding recommended
actions are adequate to reduce risk to an acceptable level. Talk with the team to ensure
they are satisfied all high risk is addressed and no important concerns are left
unaddressed.
FMECA Quality Audit Procedure
FMECA Quality Audit Procedure
FMECA 10 Quality Objectives
FMECA 10 Quality Objectives
5. 
4. 
Interfaces: The FMECA scope includes integration and interface failure modes in
both block diagram and analysis.
Example A generator in an automobile was noisy by actual noise measurements in
vehicle testing. A previous FMEA on the generator revealed no issue with noise. Pulling
the generator and thoroughly testing and analyzing it showed no noise problems. It was
revealed the bracket that secured the generator to the engine frame was faulty. The
bracket was an interface between the generator and the engine frame. It is essential that
interfaces be included in FMEA analyses.
How To Audit:
Review items, functions, failure modes and other portions of the FMECA to ensure that
interface and integration issues were taken up and addressed within the scope of
FMECA. Look at Block Diagram to verify. Talk with the team inquiring how they
ensured no interface issues were missed.
!
DVP: The Design Verification Plan considers the failure modes from the FMECA.
Example A test laboratory in a large original equipment manufacturer (OEM) conducted
testing on subsystem X that passed each year. Yet, there continued to be field problems
with subsystem X. The test group was part of the engineering department and the
warranty group was in an entirely different department. Neither one talked to the other
year after year. One day, the engineering department began doing FMECAs and the
FMECA team for subsystem X asked why the current tests always passed in spite of field
failures. The test procedures were revised to detect the causes from the FMECAs so that
subsystem X tests began to fail, revealing needed design changes that ended up greatly
reducing warranty.
Example A company that uses glass in a complex system was developing a new device
with new application of existing technology. The FMECA was nearly done, and upon
review, the facilitator asked if all of the major concerns had been identified. There was
one concern, omitted from the FMECA, relating to gas bubbles in the fabrication of the
glass that the subject-matter experts knew would be present and that was high risk. The
reason for the omission was that even though they knew it would occur, no one had a
solution. Fortunately, the FMECA facilitator did the right thing and got the team to
include the high-risk failure mode in the FMEA, and the team subsequently generated a
series of recommended actions, including enlisting outside technical support.
Lessons Learned: The FMECA considers all major “lessons learned” (such as highwarranty, campaigns, etc.) as input to failure mode identification.
Example In one automotive company, in the 1980s, there was a major hood secondary latch
bracket recall costing millions of dollars. The root cause was fatigue cracking of the bracket. The
problem was resolved with an improved bracket design. However, this problem and its solution
were never recorded in a field problem database from which future program design engineers
could easily retrieve and use the information. A few years later, the same problem occurred on a
hood secondary latch on a different vehicle program, and a second, more expensive recall
occurred. At this point, the company decided to use FMECAs as the mechanism to prevent field
problem recurrences. All future FMECAs were required to include past field problems as failure
modes/causes on FMECAs for similar designs, with the FMECA team held accountable to
ensure that problems did not recur.
How To Audit:
Review failure modes and causes to ensure that they contain supplemental field failure
data. Preferably, there is a visual way to see which failure modes are from field information
and how they are addressed. Talk with the FMECA team to ensure that the FMECA
benefited from field lessons learned and that high-risk issues from the field will not be
repeated.
139!
FMECA Quality Audit Procedure
FMECA Quality Audit Procedure
FMECA 10 Quality Objectives
6. 
TIMING: The FMECA is completed during the “window of opportunity” whence
it can most effectively influence the product design.
Example An executive in a computer manufacturing company heard about FMECA and
wanted to use this tool on a new line of computers almost ready to launch. Because the
equipment had already been designed and was mostly tested, the objective of this
FMECA was to find any unnoticed major problems. The resulting value of the FMECA
was much lower than if it had been done before the design and testing were completed,
as the FMECA team was by that time hesitant to recommend design changes or test
improvements.
How To Audit:
Review the timing of the FMECA project against the product development process
timing gates. Verify the FMECA was started and completed in the proper time frame for
ensuring maximum value.
8. 
FMECA 10 Quality Objectives
7.  LEVEL OF DETAIL: The FMECA provides the correct level of detail in order to get to
root causes and effective actions.
Example A vehicle integrator was developing a new transmission with new technology and new
applications of existing technology. They requested help with their reliability program. Even
though product launch was only a few months away, the System FMECA was only a third
completed, and was already over 400 pages long. This company had used automated FMECA
software that generated functions from requirements and failure modes from functions. There
are three problems with this approach: (1) lack of adequate subject-matter expert involvement,
(2) functions included that are trivial to the primary performance objectives of the system, and
(3) failure modes generated that are of no concern to the FMECA team. This approach to
FMECA is a waste of time and money.
How To Audit
Verify that the level of detail on higher risk issues is adequate to fully understand root causes
and develop effective corrective actions. Review all different columns of the FMECA to see if
the overall level of detail is proper and adequate. Too much detail shows up as endless pages of
FMECA material, including areas that no one on the FMECA team is concerned about; too little
detail shows up as under-defined functions, failure modes, effects, causes or controls. Talk with
the FMECA team to determine how they addressed the level of detail and ensured all concerns
were included in the scope of the FMECA project.
FMECA Quality Audit Procedure
FMECA Quality Audit Procedure
FMECA 10 Quality Objectives
FMECA 10 Quality Objectives
TEAM: The right people are adequately trained in the procedure and participate on
the FMECA team throughout the analysis.
Example A common practice at one military supplier was to have the reliability engineer
do the FMECAs by sitting in front of each system or design engineer separately, one by
one, and fill out the form. Even if the reliability engineer talked individually with all of
the correct FMECA team members (which was not done in this example), the quality of
the FMECA would still be lacking. One of the leading values of an FMECA is the
synergy and cross talk by the various team members, to be certain that all of the right
information is included, and nothing is missed.
How To Audit:
Review the FMECA team membership roster to ensure that there was adequate
representation from the various disciplines needed based on the scope of the project.
Check FMECA team meeting records to ensure attendance was adequate at each meeting.
Talk with the individual team members to see if their input was elicited in the decisions.
9. 
DOCUMENTATION: The FMECA document is completely filled out “by the
book” including “Action taken” and final risk assessment
Example A vehicle manufacturing company did FMECAs up to recommended actions,
and then filed them. In this instance, it was thought the primary purpose was to fill out
the FMECA form. This is the wrong purpose for conducting FMECAs and provides little
or no real value. The value of the FMEA is in the open dialog by subject-matter experts
leading to specific changes in design, evaluation and/or manufacturing process, and the
execution of the recommendations. If the recommended changes are done but are not
recorded, the company may be legally vulnerable. If the recommended changes are not
done, risk is not reduced to an acceptable level.
How To Audit:
Look at the FMECA to see if the various columns were properly filled out and that
FMECA best practice procedure was followed. Talk with the FMECA team to ensure
they rigorously followed FMECA guidelines and practices.
FMECA Quality Audit Procedure
FMECA 10 Quality Objectives
10.  TIME USAGE: Time spent by the FMECA team is an effective and efficient use of
time with a value added result.
Example In an FMECA audit, the auditor asked the FMECA team members what they
thought of the value of doing that particular FMECA. The FMECA had looked
reasonably good in terms of completion, but the auditor wanted to find out if the
individual team members thought their time was well spent in terms of what was learned
from the FMECA exercise. The answer from some team members revealed they thought
their time was wasted. The auditor found that the FMECA facilitator did not do the
FMECA preparation steps very well and the FMECA team members had to wait more
than once for information to be gathered that should have been prepared before the
meetings began. These team members thought they had little reason to show up for the
next FMECA.
How To Audit:
Talk with the FMECA team to see if each member believes his time was well spent and a
value added result was achieved. If any issues arise, find out why.
!
140!
4 Templates, Scales and Checklists
!
4.1 Checklist for FMECA Preparation
• Preparation Tasks Done Once for All FMECA
Projects
! FMECA Software Selection
! Selecting or Modifying FMECA Scales and
Columns
! Identifying Roles and Responsibilities
! FMEA Team Training
! Legal Guidelines for Doing FMECAs
! Meeting Logistics
! Defining the System Hierarchy
! Access to Failure Information
!
!
!
• Preparation*Tasks*for*Each*New*FMEA*Project!
!
! Determine!the!Scope!of!the!Analysis!
! Make!the!Scope!Visible:!
! FMECA!Block!Diagram!
! Parameter!Diagram!(PJDiagram)!
! FMEA!Interface!Matrix!
! Functional!Block!Diagram!
! Assemble!the!Correct!Team!
! Establish!the!Ground!Rules!and!Assumptions!
! Establish!the!Role!of!Suppliers!
! Gather!and!Review!Relevant!Information!
! “Gather!Information!Checklist”!!
!
141!
! Prepare!FMECA!Software!for!First!Team!
Meeting!
! “ReadyJforJFirstJMeeting!Checklist”!
!
4.2 Gather Information Checklist
The following information needs to be readily available to
the FMECA team.
! System hierarchy
! Past FMECAs
! Warranty, recalls, and other field history
! Engineering requirements (functional, performance,
operating environments, etc.)
! Drawings and schematics
! Applicable government or safety regulations
! Test procedures
! Preliminary Design Verification Plan
! Preliminary test data (if available)
! FMECA Block Diagram, P-Diagram, FMECA
interface matrix, and Functional Block Diagram
! Quality Function Deployment (QFD) (if available)
! Results of design concept selection or trade-off studies
! Actual parts (similar to design intent)
! List of specific design changes
! Other information in addition to field history and test
results that will help establish failure frequencies
! Other documents and information that highlight the
nature of the design concept
!
142!
4.3 Ready for First Meeting Checklist
This checklist helps ensure that all the necessary steps are
completed before the first FMECA team meeting.
! The FMECA scales, worksheet, and procedure have been
agreed upon and loaded into the FMECA software (if
used).
! The FMECA project has been selected based on an
identified need or preliminary risk assessment.
! The FMECA team has been identified and notified of the
upcoming FMECA.
! The FMECA team is trained in proper FMECA procedure.
! An FMECA facilitator or team leader has been assigned
and is trained in how to effectively facilitate FMECAs.
! The proper FMEA procedure is available for use by the
FMECA team.
! Management supports the FMECA project and will help
to ensure it is done properly with good attendance.
! The scope of the FMECA is well defined and agreed
upon.
! FMECA Block Diagram, P-Diagram, FMECA Interface
Matrix, and Functional Block Diagram have been done, as
needed.
! The ground rules and assumptions have been identified
and agreed upon.
! All of the relevant information has been gathered in
preparation for the upcoming FMECA.
!
143!
4.4 Checklist of Function Types
There are different types of functions. Basic functions fulfill
the purpose of a product. Interface functions should be
included when they are within the scope of the analysis.
Additional functions may be added regarding safety,
reliability, product appeal, laws and regulations, product
installation, portability, storage, and so on.
Here is a checklist of the various types of functions to help
ensure that no primary functions are missed when
performing an FMEA. Choose the types of functions that
apply to the given analysis.
! Basic functions (the primary purpose of a product,
usually obtained from requirements or specification
documents)
! Interface functions (from the FMEA Block Diagram or
FMEA interface matrix)
! Safety functions (during manufacture or use)
! Reliability functions (life of the product)
! Product appeal functions
! Ergonomic functions
! Human interaction functions
! Legal and regulatory functions
! Functions relating to product installation
! Packaging and shipping functions
! Fluid retention functions
! Service functions
! Storage functions
! Design for manufacturing or assembly functions
!
144!
4.5 Five Whys
Many practitioners use repeated questioning of the FMEA team to ensure
that the basic “why” is determined as the cause of a failure mode. This
technique, called the Five Whys, can be very helpful, especially when the
root cause is not forthcoming. The Five Whys is a technique developed by
Taiichi Ohno, originator of the Toyota Production System. It means that
by asking “why” five times, the team will be able to discover the
progression of cause-and-effect relationships behind a problem and the
root cause that is below the surface.
Five Whys Example
• Why does the cable break?!
Answer: Because the stress from the most extreme in-use operating
conditions exceeds the strength of the cable.
• Why does the stress from the most extreme in-use operating conditions
exceed the strength of the cable? !
Answer: Because the strength of the current cable material can
degrade under certain extreme environmental operating conditions.
• Why can the strength of the current cable material degrade under certain
extreme environmental operating conditions? !
Answer: Because the current cable material corrodes when
exposed to extreme hot and moist environments.
• Why does the current cable material corrode when exposed to extreme
hot and moist operating environments? !
Answer: Because the current cable material is not suitable for the
most extreme operation conditions for the all-terrain bicycle.
• Why is the current cable material not suitable for the most extreme
operation conditions for the all-terrain bicycle?
Answer: Because the cable supplier selected the wrong material for
the brake cable.
!
145!
4.6 Templates
!
!
4.6.1 Design-FMECA Template
4.6.2 MAchinery-FMECA Template
!
!
!
146!
4.7 Scales
4.7.1 Design-FMECA Severity Scale
!
4.7.2 Machinery-FMECA Severity Scale
!
!
!
!
!
!
!
!
147!
4.7.3 Design-FMECA Occurrence Scale
!
!
!
!
!
4.7.4 Machinery-FMECA Occurrence Scale
!
!
!
!
!
!
!
!
!
!
148!
4.7.5 Design-FMECA Detection Scale
!
!
!
!
4.7.6 Design-FMECA Detection Scale
!
!
!
!
!
!
149!
4.8 Quality and Reliability Resources to Help
Formulate FMECA Recommended Actions
The following is a short list of quality and reliability resources available
to FMECA teams to support research in development of effective
FMECA recommendations.
• Applied Reliability Symposium, http://www.arsymposium.org/
• Reliability and Maintainability Symposium, http://rams.org/
• The Center for Advanced Life Cycle Engineering (CALCE),
University of Maryland, http://www.calce.umd.edu/
• Reliability
Engineering
Resource
web
site,
http://www.weibull.com/
• Society of Automotive Engineers (SAE) JA1000/1 Reliability
Program Standard Implementation Guide, 1999
• Assurance Technologies Principles and Practices: A Product,
Process and System Safety Perspective, 2nd edition, by Dev G.
Raheja and Michael Allocco, Wiley-Interscience, 2006
• Practical Reliability Engineering, 5th edition, by Patrick O’Connor
and Andre Kleyner, Wiley, 2012
• Improving Product Reliability: Strategies and Implementation, by
Mark A. Levin and Ted T. Kalal, Wiley, 2003
• Accelerated Reliability Engineering: HALT and HASS, 1st edition,
by Gregg Hobbs, John Wiley & Sons, 2000
• Product Reliability, Maintainability, and Supportability Handbook,
2nd edition, by Michael Pecht, CRC Press, 2009
• Design for Six Sigma: A Roadmap for Product Development, 2nd
edition, by Kai Yang and Basem EI-Haik, McGraw-Hill, 2008
• Design for Reliability (Quality and Reliability Series), 1st edition,
by Dev G. Raheja, Wiley, 2012
There are also many excellent web sites of professional organizations,
such as American Society of Quality (ASQ), Society of Automotive
Engineers (SAE), Institute of Environmental Sciences and Technology
(IEST), Institute of Electrical and Electronics Engineers (IEEE),
International System Safety Society (ISSS), Society of Reliability
Engineers (SRE), and many others.
In summary, there is a wealth of methods and tools available in the fields
of quality and reliability. They should be made available to FMECA
teams in their search for answers, and should be used to broaden the tools
available to FMECA team members in resolving high-risk issues.!
!
!
!
!
!
150!