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By Dick Seidl, Global Applications Engineering Director, Stanley Engineered Fastening
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asteners are essential to modem life,
however, it is easy to forget just what
an important role the small fastener
plays in the integrity and safety of the end
product. Automakers have reported that the
majority of their warranty costs arise from
fastener related issues - ranging fi'om the
simple rattle in the dashboard coming from
a loose tapping screw to a major recall
resulting from mis-torqued high Stl'ength
fasteners in the steering system. Many
problems relate back to the not-so-simple
fastener.
Fastener Quality Act
In the 1980s, there were a series of
product failures that were attributed to
counterfeit or substandard threaded fasteners. Fasteners were being offered for sale
that were mismarked in material and heat
treatment or were dimensionally noncon-
forming to the appropriate standards. The
most common of these counterfeits was
the intentional mismarking of low-carbon
boron steel Grade 8.2 bolts as alloy steel
Grade 8.0. The mismarked low-carbon
boron.steel bolts have the potential for long
term stress relaxation failures under certain
conditions. After a number of product failures were publicized, Congress decided to
protect the public from the dangers related
to substandard fasteners and in 1990, the
Fastener Quality Act (FQA) was passed
into law. Since that time, several amendments to the FQA have been implemented.
The law, as passed in 1990, was never
implemented in its original form. The
intent of law was to assure that all 'critical'
fasteners were properly marked for identification and properly tested to assure quality.
The initial law contained requirements that
virtually all quality inspections were to
be based on sampling and testing of product. This was going to take the place of
in-process controls and SPC, which most
manufactures considered to be a step back
rather than forward in quality. The law also
required the use of NIST-accredited laboratories tbr all testing. The requirement for
sampling negated the advantages gained by
the use of modern process control methodologies and added significantly to cost
and lead time, without improving resultant
quality compared to properly conducted
SPC. The NIST lab accreditation requirement mandated that all in-house labs that
did any test on a part needed accreditation,
meaning thousands of manufacturer and
distributor labs suddenly needed accreditation, resulting in a log jam of applications.
Prior to implementation of the FQA act, it
was amended in 1997. The most significant
change created by this amendment was a
provision to allow the use of SPC and process conu'ol systems to show conformance
to the FQA. Companies that could show
certification that they were operating under
an accredited Quality Assurance System
(ISO 9000, AS 9100, etc) were declared
provisionally compliant with the FQA.
In 1999, another amendment to the FQA
was signed by the president. This amend-
ment included significant changes to both
the scope and implementation of the FQA:
• Limited the scope of covered fasteners to those fasteners that are both
through hardened and grade marked.
• Eliminated the requirement for NIST
approval of lab accreditations.
• Exempted manufacturers using quality management systems based on ISO
9000, ISO 9001, ISO 9002, or ISO/
TS 16949 from the FQA regulations.
• Allowed electronic storage and transmittal of records if they had effective
systems to prevent alteration.
The cun'ent focus of the FQA is to prevent
the fraud that was occurring during the late
'80s with mismarking and falsified certifications. There were individuals and organizations who sought to take advantage of the
situation by fraudulently selling product at
a higher than normal marÿn. The FQA has
reduced but certainly not eliminated this.
Quality Fasteners
The biggest impact on fastener quality during the past 20 years has been the
adoption of process control methodology.
"Fastener standards are governed by many organizations around the world," says Fastenal's Chris Williamson, director of
quality and engineering. In the U.S., we most frequently reference standards from the following organizations, he says:
• SAE Fastener Committee: A variety of fastener standards including SAE J429, the most common specification for
material grades of standard inch series hex cap screws and hex bolts
• ASTM F16: A group composed of a main committee and many subcommittees, most frequently used for material and
mechanical properties as well as testing and inspection requirements for fasteners.
• ASME B18: A group composed of a main committee and many subcommittees, most frequently used for dimensional
requirements and a basic governing quality plan.
• ISO TC/2: A group consisting of many member countries with the most relevant specifications for dimensions, material, and quality requirements of metric fasteners.
American manufacturers are producing higher quality and more reliable fasteners, he says, and "intense competition and
greater use expectation has had a dramatic impact on quality over time."
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This has both improved quality
through the use of statistical
and predictive controls and also
reduced cost through the reduction in associated scrap and
their manufacturing and inspection processes. By utilizing consensus standards, the consensus
specification body takes care of
this process for the user.
rework. The use of processes
like SPC has allowed producers
and users to better communicate
processes and quality standards
using a common language. End
users should be careful to add
SPC controls to those characteristics where such control will
enhance resulting product quality - thread pitch diameter and
hardness are two key ones.
Most fastener products now
are controlled by customer drawings and mechanical
requirements (ISO 898-1,
ASTM A354, etc) or consensus dimensional standards and
mechanical requirements. Few
end users have the support
staff available to generate and
properly maintain their own
fastener standards, so there is an
increase in the use of consensus
standards rather than proprietary
standards at many companies.
The use of consensus stan-
dards for mechanical properties
helps assure the correct alloys
and requirements are utilized,
while allowing specific dimensional requirements to be easily addressed on a drawing by
drawing basis.
During the past decade, there
have been a number of evolu-
tionary changes to the fastener
specifications to match revised
material and testing/inspection
specifications to the appropriate fastener specifications.
One of the areas where utilization of consensus standards
by a company is a tremendous
help is during the revision of
these associated specifications
such as raw material or testing
protocols. If a company maintains their own specifications,
they need to have an engineer
reviewing each and every one of
the linked specifications to see
how any revisions will affect
The Right Choice
The vast majority of fastener
related problems have nothing to do with fastener quality
problems, rather they relate
back to improper selection or
installation of the fastener. As
companies have become more
aware that the hardware cost of
the fasteners accounts for only
15-35 percent of the in-place
cost of the fastener, they have
become more interested in
exploring ways to reduce the
installation costs. This has led
to significant growth in the area
of engineered fastener designs,
fasteners designed for use in a
particular application.
The development of engineered fasteners allows the use
of products like high performance thread forming screws
that, in addition to elinfinating
the tapping operation, simultaneously eliminate cross threading while providing vibration
resistance that meets locking
screw standards. Not only is
there a reduction in the cost of
preparation and installation,
there is also an increase in joint
quality and integrity.
The increasing use of engineering grade plastics has also
created fastening challenges.
The key is to work with an
experienced fastener application engineer to assure that the
design is sound prior to making
the fmal production mold for
the plastic part. The application
engineer can help do this by
molding and testing trial bosses
to help validate the design
Fastener professionals can
make fastening suggestions that
can result in major cost savings
over the life of the product,
while providing increased product quality and integrity, tmPo
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