Multiprocess 175 Operating manual

Multiprocess 175 Operating manual
Multiprocess 175
Operating manual
2
BOC Smootharc Multiprocess 175 Operating manual
Welcome to a better way of welding.
This operating manual provides the basic knowledge required for MIG/
MAG, TIG and MMA welding, as well as highlighting important areas of
how to operate the Smootharc Multiprocess 175 machine.
With normal use and by following these recommended steps, your
Smootharc Multiprocess 175 machine can provide you with years of
trouble-free service. Smootharc equipment and technical support is
available through the national BOC Customer Service Centre or contact
your local Gas & Gear outlet.
Important Notice
This document has been prepared by BOC Limited ABN 95 000 029 729 (‘BOC’), as general information and does not contain and is not to be taken as containing any specific recommendation. The document has been prepared in good faith
and is professional opinion only. Information in this document has been derived from third parties, and though BOC believes it to be reliable as at the time of printing, BOC makes no representation or warranty as to the accuracy, reliability or
completeness of information in this document and does not assume any responsibility for updating any information or correcting any error or omission which may become apparent after the document has been issued. Neither BOC nor any of
its agents has independently verified the accuracy of the information contained in this document. The information in this document is commercial in confidence and is not to be reproduced. The recipient acknowledges and agrees that it must
make its own independent investigation and should consider seeking appropriate professional recommendation in reviewing and evaluating the information. This document does not take into account the particular circumstances of the recipient
and the recipient should not rely on this document in making any decisions, including but not limited to business, safety or other operations decisions. Except insofar as liability under any statute cannot be excluded, BOC and its affiliates,
directors, employees, contractors and consultants do not accept any liability (whether arising in contract, tort or otherwise) for any error or omission in this document or for any resulting loss or damage (whether direct, indirect, consequential
or otherwise) suffered by the recipient of this document or any other person relying on the information contained herein. The recipient agrees that it shall not seek to sue or hold BOC or their respective agents liable in any such respect for the
provision of this document or any other information.
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BOC Smootharc Multiprocess 175 Operating manual
Contents.
1.0Recommended Safety Guidelines and Precautions
4
1.1
1.2
1.3 1.4
Health Hazard Information
Personal Protection
Electrical shock User Responsibility
5
5
7
7
2.0 MIG/MAG Operating Manual
8
2.1Introduction to Metal Inert Gas (MIG) & Metal Active Gas (MAG)
2.2Introduction to Flux Cored Arc Welding (FCAW)
2.3Introduction to Metal Cored Arc Welding (MCAW)
2.4 Modes of metal transfer 2.5Fundamentals of MIG/MAG, FCAW and MCAW
2.6 4T/2T Trigger Latch Selection
8
8
10
11
13
15
3.0 Gas tungsten arc welding (GTAW/TIG)
16
3.1 Introduction 3.2 Process 3.3 Process variables
3.4 Shielding gas selection
3.5 Welding wire selection
3.6 Tungsten electrode selection 3.7 Welding techniques 3.8 Torch movement during welding
3.9Positioning torch tungsten for various weld joints
3.10 Joint preparation
16
16
17
18
18
19
21
21
22
23
4.0Manual Metal Arc Welding Process (MMAW)
25
4.1Introduction
4.2Process
4.3 Welding Machine
4.4 Welding Technique
4.5 Electrode Selection 4.6 Types of Joints 4.7 Fillet Welds 4.8 Typical Defects Due to Faulty Technique 25
25
26
26
26
29
31
33
5.0 General Welding Information
35
5.1
35
Recommended Welding Parameters for MIG/MAG
6.0 Correct Application Techniques
36
7.0 Package Contents
38
8.0 Smootharc Multiprocess 175 Installation
39
8.1
8.2
8.3
39
40
40
Installation for MIG/MAG process
Installation for TIG setup
Installation for MMA process
9.0 Control panels
41
9.1
41
Polarity selection
10.0 Smootharc Multiprocess 175 Operation
42
10.1
10.2
10.3
10.4
42
42
43
44
Starting up
Operation for MMA mode
Operation instruction under LIFT TIG mode
Operation instruction under MIG mode
11.0 Troubleshooting and Fault Finding
46
11.1 TIG/MMA functions
11.2 MIG/MAG functions
46
48
12.0 Periodic Maintenance
50
12.1 Power Source
50
13.0 Technical Specifications
51
14.0 Warranty Information
52
14.1
14.2
14.3
14.4
52
52
52
52
Terms of Warranty Limitations on Warranty
Warranty Period
Warranty Repairs
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BOC Smootharc Multiprocess 175 Operating manual
1.0Recommended Safety Guidelines
and Precautions
Diagram and safety explanation
Electrical safety alert
Welding electrode causing electric shock
Fumes and gases coming from welding process
Welding arc rays
Some safety precautions BOC
recommends are as follows:
• Repair or replace defective cables immediately.
Read instruction manual
• Never watch the arc except through
lenses of the correct shade.
• In confined spaces, adequate ventilation
and constant observation are essential.
Become trained
Wear dry, insulated gloves
• Leads and cables should be kept clear
of passageways.
• Keep fire extinguishing equipment at a handy location
in the workshop.
• Keep primary terminals and live parts effectively covered.
Insulate yourself from work and ground
• Never strike an arc on any gas cylinder.
• Never use oxygen for venting containers.
Disconnect input power before working on equipment
Keep head out of fumes
Use forced ventilation or local exhaust to remove fumes
Use welding helmet with correct shade of filter
BOC Smootharc Multiprocess 175 Operating manual
1.1 Health Hazard Information
The actual process of welding is one that can cause a variety of hazards.
All appropriate safety equipment should be worn at all times, i.e.
headwear, hand and body protection. Electrical equipment should be
used in accordance with the manufacturer’s recommendations.
Eyes
The process produces ultra violet rays that can injure and cause
permanent damage. Fumes can cause irritation.
Skin
Arc rays are dangerous to uncovered skin.
Inhalation
Welding fumes and gases are dangerous to the health of the operator
and to those in close proximity. The aggravation of pre-existing
respiratory or allergic conditions may occur in some workers. Excessive
exposure may cause conditions such as nausea, dizziness, dryness and
irritation of eyes, nose and throat.
• Fumes from the welding of some metals could have an adverse effect
on your health. Don’t breathe them in. If you are welding on material
such as stainless steel, nickel, nickel alloys or galvanised steel, further
precautions are necessary.
• Wear a respirator when natural or forced ventilation is insufficient.
Eye protection
A welding helmet with the appropriate welding filter lens for the
operation must be worn at all times in the work environment. The
welding arc and the reflecting arc flash gives out ultraviolet and infrared
rays. Protective welding screen and goggles should be provided for
others working in the same area.
Recommended filter shades for arc welding
Less than 150 amps
150 to 250 amps
250 to 300 amps
300 to 350 amps
Over 350 amps
Shade 10*
Shade 11*
Shade 12
Shade 13
Shade 14
1.2 Personal Protection
*Use one shade darker for aluminium.
Respiratory
Confined space welding should be carried out with the aid of a fume
respirator or air supplied respirator as per AS/NZS 1715 and AS/NZS 1716
Standards.
Clothing
Suitable clothing must be worn to prevent excessive exposure to UV
radiation and sparks. An adjustable helmet, flameproof loose-fitting
cotton clothing buttoned to the neck, protective leather gloves, spats,
apron and steel capped safety boots are highly recommended.
• You must always have enough ventilation in confined spaces. Be alert
to this at all times.
• Keep your head out of the fumes rising from the arc.
5
6
BOC Smootharc Multiprocess 175 Operating manual
1
2
3
Back view of typical cylinder valve.
Operator wearing personal
protective equipment (PPE)
in safe position.
Cylinder safety diagram
1
2
3
Cylinder valve hand-wheel
Back-plug
Bursting disc
Ten points about cylinder safety
1
2
3
4
5
6
7
8
9
10
Read labels and Material Safety Data Sheet (MSDS) before use
Store upright and use in well ventilated, secure areas away from
pedestrian or vehicle thoroughfare
Guard cylinders against being knocked violently or being allowed
to fall
Wear safety shoes, glasses and gloves when handling and
connecting cylinders
Always move cylinders securely with an appropriate trolley. Take
care not to turn the valve on when moving a cylinder
Keep in a cool, well ventilated area, away from heat sources,
sources of ignition and combustible materials, especially
flammable gases
Keep full and empty cylinders separate
Keep ammonia-based leak detection solutions, oil and grease
away from cylinders and valves
Never use force when opening or closing valves
Don’t repaint or disguise markings and damage. If damaged,
return cylinders to BOC immediately
Cylinder valve safety
When working with cylinders or operating cylinder valves, ensure
that you wear appropriate protective clothing – gloves, boots and
safety glasses.
When moving cylinders, ensure that the valve is not accidentally opened
in transit.
Before operating a cylinder valve
Ensure that the system you are connecting the cylinder into is suitable for
the gas and pressure involved.
Ensure that any accessories (such as hoses attached to the cylinder valve,
or the system being connected to) are securely connected. A hose, for
example, can potentially flail around dangerously if it is accidentally
pressurised when not restrained at both ends.
Stand to the side of the cylinder so that neither you nor anyone else is
in line with the back of the cylinder valve. This is in case a back-plug
is loose or a bursting disc vents. The correct stance is shown in the
diagram above.
When operating the cylinder valve
Open it by hand by turning the valve hand-wheel anti-clockwise. Use
only reasonable force.
Ensure that no gas is leaking from the cylinder valve connection or
the system to which the cylinder is connected. DO NOT use ammoniabased leak detection fluid as this can damage the valve. Approved leak
detection fluid, can be obtained from a BOC Gas & Gear centre.
When finished with the cylinder, close the cylinder valve by hand
by turning the valve hand-wheel in a clockwise direction. Use only
reasonable force.
Remember NEVER tamper with the valve.
If you suspect the valve is damaged, DO NOT use it. Report the issue to
BOC and arrange for the cylinder to be returned to BOC.
BOC Smootharc Multiprocess 175 Operating manual
1.3 Electrical shock
• Never touch ‘live’ electrical parts.
BOC stock a huge range of personal protective equipment. This combined
with BOC’s extensive Gas and Gear network ensures fast, reliable service
throughout the South Pacific.
• Always repair or replace worn or damaged parts.
• Disconnect power source before performing any maintenance
or service.
• Earth all work materials.
• Never work in moist or damp areas.
Avoid electric shock by:
• Wearing dry insulated boots.
STOP
PLEASE NOTE that under no circumstances should any
equipment or parts be altered or changed in any way from the
standard specification without written permission given by
BOC. To do so, will void the Equipment Warranty.
• Wearing dry leather gloves.
• Working on a dry insulated floor where possible.
1.4 User Responsibility
• Read the Operating Manual prior to installation of this machine.
• Unauthorised repairs to this equipment may endanger the technician
and operator and will void your warranty. Only qualified personnel
approved by BOC should perform repairs.
• Always disconnect mains power before investigating
equipment malfunctions.
• Parts that are broken, damaged, missing or worn should be
replaced immediately.
• Equipment should be cleaned periodically.
7
Further information can be obtained from Welding Institute of Australia
(WTIA) Technical Note No.7.
Health and Safety Welding
Published by WTIA,
PO Box 6165 Silverwater NSW 2128
Phone (02) 9748 4443
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BOC Smootharc Multiprocess 175 Operating manual
2.0 MIG/MAG Operating Manual
Typical MIG/MAG set up
Torch
Torch trigger
Shroud
Gas diffuser
Contact tip
Welding wire
Weld
Shielding
Droplets
Weld pool
2.1Introduction to Metal Inert Gas (MIG)
& Metal Active Gas (MAG)
• Argon with oxygen mixtures (MAG)
MIG/MAG welding embraces a group of arc welding processes in which
a continuous electrode (the wire) is fed by powered feed rolls (wire
feeder) into the weld pool. An electric arc is created between the tip of
the wire and the weld pool. The wire is progressively melted at the same
speed at which it is being fed and forms part of the weld pool. Both the
arc and the weld pool are protected from atmospheric contamination by
a shield of inert (non-reactive) gas, which is delivered through a nozzle
that is concentric with the welding wire guide tube.
Each gas or gas mixture has specific advantages and limitations. Other
forms of MIG/MAG welding include using a flux-cored continuous
electrode and carbon dioxide shielding gas, or using self-shielding fluxcored wire, requiring no shielding.
Operation
MIG/MAG welding is usually carried out with a handheld torch as a semiautomatic process. The MIG/MAG process can be suited to a variety of job
requirements by choosing the correct shielding gas, electrode (wire) size
and welding parameters. Welding parameters include the voltage, travel
speed, arc (stick-out) length and wire feed rate. The arc voltage and wire
feed rate will determine the filler metal transfer method.
How it Works
Flux-cored arc welding (FCAW) uses the heat generated by a DC electric
arc to fuse the metal in the joint area, the arc being struck between a
continuously fed consumable filler wire and the workpiece, melting both
the filler wire and the workpiece in the immediate vicinity. The entire arc
area is covered by a shielding gas, which protects the molten weld pool
from the atmosphere.
This application combines the advantages of continuity, speed,
comparative freedom from distortion and the reliability of automatic
welding with the versatility and control of manual welding. The process
is also suitable for mechanised set-ups, and its use in this respect
is increasing.
FCAW is a variant of the MIG/MAG process and while there are many
common features between the two processes, there are also several
fundamental differences.
MIG/MAG welding can be carried out using solid wire, flux cored, or a
copper-coated solid wire electrode. The shielding gas or gas mixture may
consist of the following:
• Argon (MIG)
• Carbon dioxide (MAG)
• Argon and carbon dioxide mixtures (MAG)
• Argon with helium mixtures (MIG)
2.2Introduction to Flux Cored
Arc Welding (FCAW)
As with MIG/MAG, direct current power sources with constant voltage
output characteristics are normally employed to supply the welding
current. With flux-cored wires the terminal that the filler wire is
connected to depends on the specific product being used, some wires
running electrode positive, others running electrode negative. The work
return is then connected to the opposite terminal. It has also been found
that the output characteristics of the power source can have an effect on
the quality of the welds produced.
BOC Smootharc Multiprocess 175 Operating manual
9
Extended self shielded flux cored wire nozzle
The wire feed unit takes the filler wire from a spool, and feeds it
through the welding torch, to the arc at a predetermined and accurately
controlled speed. Normally, special knurled feed rolls are used with fluxcored wires to assist feeding and to prevent crushing the consumable.
cored wire is much smaller than that of a solid MIG/MAG wire. This
means that the electrical resistance within the flux cored wire is higher
than with solid MIG/MAG wires and it is this higher electrical resistance
that gives this type of wire some of its novel operating properties.
Unlike MIG/MAG, which uses a solid consumable filler wire, the
consumable used in FCAW is of tubular construction, an outer metal
sheath being filled with fluxing agents plus metal powder. The flux fill is
also used to provide alloying, arc stability, slag cover, de-oxidation, and,
with some wires, gas shielding.
One often quoted property of fluxed cored wires are their higher
deposition rates than solid MIG/MAG wires. What is often not explained
is how they deliver these higher values and whether these can be
utilised. For example, if a solid MIG/MAG wire is used at 250 amps,
then exchanged for a flux cored wire of the same diameter, and welding
power source controls are left unchanged, then the current reading
would be much less than 250 amps, perhaps as low as 220 amps. This
is because of Ohms Law that states that as the electrical resistance
increases if the voltage remains stable then the current must fall.
In terms of gas shielding, there are two different ways in which this may
be achieved with the FCAW process.
• Additional gas-shielding supplied from an external source, such as a gas
cylinder
• Production of a shielding gas by decomposition of fluxing agents within
the wire, self-shielding
Gas shielded wires are available with either a basic or rutile flux fill,
while self-shielded wires have a broadly basic-type flux fill. The flux
fill dictates the way the wire performs, the properties obtainable, and
suitable applications.
Gas-shielded Operation
Many cored wire consumables require an auxiliary gas shield in the same
way that solid wire MIG/MAG consumables do. These types of wire are
generally referred to as ‘gas-shielded’.
Using an auxiliary gas shield enables the wire designer to concentrate on
the performance characteristics, process tolerance, positional capabilities,
and mechanical properties of the products.
In a flux cored wire the metal sheath is generally thinner than that of
a self-shielded wire. The area of this metal sheath surrounding the flux
To bring the welding current back to 250 amps it is necessary to
increase the wire feed speed, effectively increasing the amount of
wire being pushed into the weld pool to make the weld. It is this affect
that produces the ‘higher deposition rates’ that the flux cored wire
manufacturers claim for this type of product. Unfortunately in many
instances the welder has difficulty in utilising this higher wire feed speed
and must either increase the welding speed or increase the size of the
weld. Often in manual applications neither of these changes can be
implemented and the welder simply reduces the wire feed speed back
to where it was and the advantages are lost. However, if the process
is automated in some way then the process can show improvements in
productivity.
It is also common to use longer contact tip to workplace distances with
flux cored arc welding than with solid wire MIG/MAG welding and this
also has the effect of increasing the resistive heating on the wire further
accentuating the drop in welding current. Research has also shown
that increasing this distance can lead to an increase in the ingress of
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BOC Smootharc Multiprocess 175 Operating manual
Process Schematic Diagram for MIG/MAG, FCAW and MCAW
Gas hose
Continuous wire
Wire feed unit
Power cable
Torch conduit
Gas cylinder
Welding torch
Arc
Workpiece
Power source
Earth clamp
Return cable
nitrogen and hydrogen into the weld pool, which can affect the quality of
the weld.
Flux cored arc welding has a lower efficiency than solid wire MIG/
MAG welding because part of the wire fill contains slag forming agents.
Although the efficiency varies differs by wire type and manufacturer it is
typically between 75–85%.
Flux cored arc welding does, however, have the same drawback as solid
wire MIG/MAG in terms of gas disruption by wind, and screening is
always necessary for site work. It also incurs the extra cost of shielding
gas, but this is often outweighed by gains in productivity.
Self-shielded Operation
There are also self-shielded consumables designed to operate without an
additional gas shield. In this type of product, arc shielding is provided by
gases generated by decomposition of some constituents within the flux
fill. These types of wire are referred to as ‘self-shielded’.
If no external gas shield is required, then the flux fill must provide
sufficient gas to protect the molten pool and to provide de-oxidisers and
nitride formers to cope with atmospheric contamination. This leaves less
scope to address performance, arc stabilisation, and process tolerance, so
these tend to suffer when compared with gas shielded types.
Wire efficiencies are also lower, at about 65%, in this mode of operation
than with gas-shielded wires. However, the wires do have a distinct
advantage when it comes to site work in terms of wind tolerance, as
there is no external gas shield to be disrupted.
When using self-shielded wires, external gas supply is not required and,
therefore, the gas shroud is not necessary. However, an extension nozzle
is often used to support and direct the long electrode extensions that are
needed to obtain high deposition rates.
2.3Introduction to Metal Cored
Arc Welding (MCAW)
How it Works
Metal-cored arc welding (MCAW) uses the heat generated by a DC
electric arc to fuse metal in the joint area, the arc being struck between a
continuously fed consumable filler wire and the workpiece, melting both
the filler wire and the workpiece in the immediate vicinity. The entire arc
area is covered by a shielding gas, which protects the molten weld pool
from the atmosphere.
As MCAW is a variant of the MIG/MAG welding process there are many
common features between the two processes, but there are also several
fundamental differences.
As with MIG/MAG, direct current power sources with constant voltage
output characteristics are normally employed to supply the welding
current. With metal-cored wires the terminal the filler wire is connected
to depends on the specific product being used, some wires designed to
run on electrode positive, others preferring electrode negative, and some
which will run on either. The work return lead is then connected to the
opposite terminal. Electrode negative operation will usually give better
positional welding characteristics. The output characteristics of the power
source can have an effect on the quality of the welds produced.
The wire feed unit takes the filler wire from a spool or bulk pack, and
feeds it through the welding torch, to the arc at a predetermined and
accurately controlled speed. Normally, special knurled feed rolls are used
with metal-cored wires to assist feeding and to prevent crushing the
consumable.
Unlike MIG/MAG, which uses a solid consumable filler wire, the
consumable used in MCAW is of tubular construction, an outer metal
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BOC Smootharc Multiprocess 175 Operating manual
Schematic of Dip Transfer
1
2
3
4
5
6
Short circuit
Necking
Arc re-ignition
Arc established
Arc gap shortens
Short circuit
1
2
3
4
5
6
Time
Current (A)
Voltage (V)
Short circuit cycle
sheath being filled entirely with metal powder except for a small amount
of non-metallic compounds. These are added to provide some arc
stability and de-oxidation.
MCAW consumables always require an auxiliary gas shield in the
same way that solid MIG/MAG wires do. Wires are normally designed
to operate in argon-carbon dioxide or argon-carbon dioxide-oxygen
mixtures or carbon dioxide. Argon rich mixtures tend to produce lower
fume levels than carbon dioxide.
As with MIG/MAG, the consumable filler wire and the shielding gas are
directed into the arc area by the welding torch. In the head of the torch,
the welding current is transferred to the wire by means of a copper alloy
contact tip, and a gas diffuser distributes the shielding gas evenly around
a shroud which then allows the gas to flow over the weld area. The
position of the contact tip relative to the gas shroud may be adjusted to
limit the minimum electrode extension.
Modes of metal transfer with MCAW are very similar to those obtained
in MIG/MAG welding, the process being operable in both ‘dip transfer’
and ‘spray transfer’ modes. Metal-cored wires may also be used in
pulse transfer mode at low mean currents, but this has not been widely
exploited.
2.4 Modes of metal transfer
The mode or type of metal transfer in MIG/MAG and MCAW welding
depends upon the current, arc voltage, electrode diameter and type of
shielding gas used. In general, there are four modes of metal transfer.
Modes of metal transfer with FCAW are similar to those obtained in MIG/
MAG welding, but here the mode of transfer is heavily dependent on the
composition of the flux fill, as well as on current and voltage.
Arcing cycle
The most common modes of transfer in FCAW are:
• Dip transfer
• Globular transfer
• Spray transfer
• Pulsed arc transfer operation has been applied to flux-cored wires but,
as yet, is not widely used because the other transfer modes are giving
users what they require, in most cases.
Dip Transfer
Also known as short-circuiting arc or short-arc, this is an all-positional
process, using low heat input. The use of relatively low current and arc
voltage settings cause the electrode to intermittently short-circuit with
the weld pool at a controlled frequency. Metal is transferred by the wire
tip actually dipping into the weld pool and the short-circuit current is
sufficient to allow the arc to be re-established. This short-circuiting mode
of metal transfer effectively extends the range of MIG/MAG welding to
lower currents so thin sheet material can readily be welded. The low
heat input makes this technique well-suited to the positional welding
of root runs on thick plate, butt welds for bridging over large gaps and
for certain difficult materials where heat input is critical. Each shortcircuit causes the current to rise and the metal fuses off the end of the
electrode. A high short-circuiting frequency gives low heat input. Dip
transfer occurs between ±70-220A, 14–23 arc volts. It is achieved using
shielding gases based on carbon dioxide and argon.
Metal-cored wires transfer metal in dip mode at low currents just like
solid MIG/MAG wires. This transfer mode is used for all positional work
with these types of wire.
12
BOC Smootharc Multiprocess 175 Operating manual
Schematic of Globular Transfer
Schematic of Spray Transfer
Gas shroud
Shielding gas
Wire
Droplets
Large droplet
Splatter
Workpiece
Globular Transfer
Metal transfer is controlled by slow ejection resulting in large, irregularlyshaped ‘globs’ falling into the weld pool under the action of gravity.
Carbon dioxide gas drops are dispersed haphazardly. With argon-based
gases, the drops are not as large and are transferred in a more axial
direction. There is a lot of spatter, especially in carbon dioxide, resulting
in greater wire consumption, poor penetration and poor appearance.
Globular transfer occurs between the dip and spray ranges. This mode of
transfer is not recommended for normal welding applications and may
be corrected when encountered by either decreasing the arc voltage
or increasing the amperage. Globular transfer can take place with any
electrode diameter.
Basic flux-cored wires tend to operate in a globular mode or in a
globular-spray transfer mode where larger than normal spray droplets
are propelled across the arc, but they never achieve a true spray
transfer mode. This transfer mode is sometimes referred to as non-axial
globular transfer.
Self-shielded flux-cored wires operate in a predominantly globular
transfer mode although at high currents the wire often ‘explodes’ across
the arc.
Spray Transfer
In spray transfer, metal is projected by an electromagnetic force from
the wire tip in the form of a continuous stream of discrete droplets
approximately the same size as the wire diameter. High deposition
rates are possible and weld appearance and reliability are good. Most
metals can be welded, but the technique is limited generally to plate
thicknesses greater than 6mm. Spray transfer, due to the tendency of
the large weld pool to spill over, cannot normally be used for positional
Weld
Workpiece
welding. The main exception is aluminium and its alloys where, primarily
because of its low density and high thermal conductivity, spray transfer
in position can be carried out.
The current flows continuously because of the high voltage maintaining a
long arc and short-circuiting cannot take place. It occurs best with argonbased gases.
In solid wire MIG/MAG, as the current is increased, dip transfer passes
into spray transfer via a transitional globular transfer mode. With metalcored wires there is virtually a direct transition from dip transfer to spray
transfer as the current is increased.
For metal cored wire spray transfer occurs as the current density
increases and an arc is formed at the end of the filler wire, producing
a stream of small metal droplets. Often the outside sheath of the wire
will melt first and the powder in the centre flows as a stream of smaller
droplet into the weld pool. This effect seems to give much better transfer
of alloying elements into the weld.
In spray transfer, as the current density increases, an arc is formed at the
end of the filler wire, producing a stream of small metal droplets. In solid
wire MIG/MAG this transfer mode occurs at higher currents. Flux-cored
wires do not achieve a completely true spray transfer mode but a transfer
mode that is almost true spray may occur at higher currents and can
occur at relatively low currents depending on the composition of the flux.
Rutile flux-cored wires will operate in this almost-spray transfer mode, at
all practicable current levels. They are also able to operate in this mode
for positional welding too. Basic flux-cored and self-shielded flux-cored
wires do not operate in anything approaching true spray transfer mode.
BOC Smootharc Multiprocess 175 Operating manual
13
Typical Metal Transfer Mode
Dip
Transfer
Globular
Transfer
Metal Inert Gas (MIG)
Metal Active Gas (MAG)
�
�
�
Flux Cored (Gas Shielded)
�
�
�*
Flux Cored (Self Shielded)
�
�
�
Metal Cored
�
�
�
Process
Spray Transfer
* Not True Spray
Pulsed Transfer
Pulsed arc welding is a controlled method of spray transfer, using
currents lower than those possible with the spray transfer technique,
thereby extending the applications of MIG/MAG welding into the range
of material thickness where dip transfer is not entirely suitable. The
pulsed arc equipment effectively combines two power sources into one
integrated unit. One side of the power source supplies a background
current which keeps the tip of the wire molten. The other side produces
pulses of a higher current that detach and accelerate the droplets of
metal into the weld pool. The transfer frequency of these droplets is
regulated primarily by the relationship between the two currents. Pulsed
arc welding occurs between ±50-220A, 23–35 arc volts and only with
argon and argon-based gases. It enables welding to be carried out in all
positions.
2.5Fundamentals of MIG/MAG, FCAW and MCAW
Welding Technique
Successful welding depends on the following factors:
1 Selection of correct consumables
2 Selection of the correct power source
3 Selection of the correct polarity on the power source
4 Selection of the correct shielding gas
5 Selection of the correct application techniques
a Correct angle of electrode to work
b Correct electrical stickout
c Correct travel speed
6 Selection of the welding preparation
Selection of Correct Consumable
Chemical composition
As a general rule the selection of a wire is straightforward, in that it
is only a matter of selecting an electrode of similar composition to
the parent material. It will be found, however, that there are certain
applications that electrodes will be selected on the basis of its
mechanical properties or level of residual hydrogen in the weldmetal.
Solid MIG/MAG wires are all considered to be of the 'low Hydrogen type'
consumables.
The following table gives a general overview of the selection of some of
the BOC range of MIG/MAG wires for the most common materials.
14
BOC Smootharc Multiprocess 175 Operating manual
Cast and Helix
Cast
Helix
Cast – Diameter of the circle
Helix – Vertical height
Common Materials Welded with BOC MIG Wire
Material
AS2074 C1,C2,C3,C4-1,C4-2,C5,C6
AS/NZS1163 C250
AS/NZS3678 200,250,300
ASTM A36,A106
Stainless Steel
Grade 304/L
Grade 309
Grade 316/L
BOC MIG Wire
BOC Mild Steel MIG Wire
BOC Mild Steel MIG Wire
BOC Mild Steel MIG Wire
BOC Mild Steel MIG Wire
BOC Stainless Steel 308LSi
BOC Stainless Steel 309LSi
BOC Stainless Steel 316LSi
Physical condition
Surface condition
The welding wire must be free from any surface contamination including
mechanical damage such as scratch marks.
A simple test for checking the surface condition is to run the wire through
a cloth that has been dampened with acetone for 20 secs. If a black
residue is found on the cloth the surface of the wire is not properly
cleaned.
Cast and Helix
The cast and helix of the wire has a major influence on the feedability of
MIG/MAG wire.
If the cast is too large the wire will move in an upward direction from the
tip when welding and if too small the wire will dip down from the tip. The
result of this is excessive tip wear and increased wear in the liners.
If the helix is too large the wire will leave the tip with a corkscrew effect.
Selection of the Correct Power Source
Power sources for MIG/MAG welding is selected on a number of different
criteria, including:
1 Maximum output of the machine
2 Duty cycle
3 Output control (voltage selection, wire feed speed control)
4 Portability
The following table gives an indication of the operating amperage for
different size wires.
Wire Size
0.8 mm
0.9 mm
1.0 mm
1.2 mm
Amperage Range (A)
60–180
70–250
90–280
120–340
S election of the Correct Polarity on the Power Source
Many power sources are fitted with an optional reverse polarity dinse
connector.
To achieve the optimum welding it is important to adhere to the
consumable manufacturer's instruction to select the polarity.
As a general rule all solid and metal cored wires are welded on electrode
positive. (Work return lead fitted to the negative connector.)
Some grades of self shielded flux cored wires (i.e. E71T-11, E71T-GS etc)
needs to be welded on electrode negative. (Work return lead fitted to the
positive connector.)
BOC Smootharc Multiprocess 175 Operating manual
Selection of the Correct Shielding Gas
The selection of the shielding gas has a direct influence on the
appearance and quality of the weldbead.
The thickness of the material to be welded will determine the type of
shielding gas that has to be selected. As a general rule the thicker the
material (C-Mn and Alloy steels) are the higher the percentage of CO2 in
the shielding gas mixture.
Different grades of shielding are required for materials such as stainless
steel, aluminium and copper.
The following table gives an indication of the most common shielding
gases used for Carbon Manganese and alloy steel.
Material thickness
1–8 mm
5–12 mm
>12 mm
Recommended shielding gas
Argoshield Light
Argoshield Universal
Argoshield Heavy
More detailed selection charts, including recommendations for welding
parameters (voltage, amperage, electrical stickout, travelspeed and
gasflow rate) can be found in the following pages.
15
2.6 4T/2T Trigger Latch Selection
On all MIG machines there is no current or wire feed until the trigger on
the torch is depressed. If a welder is doing a lot of welding then he has to
hold the trigger down for long periods of time and may cause discomfort.
This is can be similar to repetitive strain injury (RSI) that has become a
very popular topic for compensation by office workers.
On all machines a special function called 2T and 4T is available. Also
referred to as trigger latching, this special feature allows the operator to
relax the trigger after first depressing it, the gas shielding to start before
the welding commences. This feature is of particular importance as it
ensures that the weld will have adequate gas shielding to eliminate the
risk of oxidisation (contaminants) causing a defective weld. (Remember,
a defective weld may not be detected by a visual inspection.)
The 2T/4T function also allows for the shielding gas to continue after the
weld has finished and cooled. This eliminates the risk of oxidation while
the weld is still in its molten state. This is particularly important when
welding stainless steel materials.
16
BOC Smootharc Multiprocess 175 Operating manual
3.0 Gas tungsten arc welding (GTAW/TIG)
Schematic of the TIG welding process
Collet
Shielding gas
Tungsten electrode
Arc
TIG filler rod
Weld pool
Workpiece
3.1 Introduction
The Tungsten Inert Gas, or TIG process, uses the heat generated by an
electric arc struck between a non-consumable tungsten electrode and
the workpiece to fuse metal in the joint area and produce a molten weld
pool. The arc area is shrouded in an inert or reducing gas shield to protect
the weld pool and the non-consumable electrode. The process may be
operated autogenously, that is, without filler, or filler may be added by
feeding a consumable wire or rod into the established weld pool.
3.2 Process
Direct or alternating current power sources with constant current output
characteristics are normally employed to supply the welding current.
For DC operation the tungsten may be connected to either output
terminal, but is most often connected to the negative pole. The output
characteristics of the power source can have an effect on the quality of
the welds produced.
Shielding gas is directed into the arc area by the welding torch and a
gas lens within the torch distributes the shielding gas evenly over the
weld area. In the torch the welding current is transferred to the tungsten
electrode from the copper conductor. The arc is then initiated by one of
several methods between the tungsten and the workpiece.
BOC Smootharc Multiprocess 175 Operating manual
3.3 Process variables
Process variable
Explanation
DCEN
Narrow bead,
deep penetration
When direct-current electrode-negative (straight polarity) For a given diameter of tungsten electrode, higher
is used:
amperage can be used with straight polarity. Straight
polarity is used mainly for welding:
• Electrons strike the part being welded at a high speed
• Intense heat on the base metal is produced
• Carbon steels
• The base metal melts very quickly
• Stainless steels
• Ions from the inert gas are directed towards the
• Copper alloys
negative electrode at a relatively slow rate
The increased amperage provides:
• Direct current with straight polarity does not require
• Deeper penetration
post-weld cleaning to remove metal oxides
• Increased welding speed
• A narrower, deeper, weld bead
Nozzle
Ions
Electrons
DCEP
Wide bead,
shallow penetration
Nozzle
Ions
Electrons
Usage
The DCEP (reverse polarity) are different from the DCEN in • Intense heat means a larger diameter of electrode must
following ways:
be used with DCEP
• Maximum welding amperage should be relatively low
• High heat is produced on the electrode rather on the
(approximately six times lower than with DCEN)
base metal
• The heat melts the tungsten electrode tip
• The base metal remains relatively cool compared to sing
straight polarity
• Relatively shallow penetration is obtained
• An electrode whose diameter is too large will reduce
visibility and increase arc instability
17
18
BOC Smootharc Multiprocess 175 Operating manual
3.4 Shielding gas selection
3.5 Welding wire selection
Material
Shielding gas
Benefits
The following table includes the recommended welding consumable for
the most commonly welded materials.
Brass
Argon
Cobalt-based alloys
Copper-nickel
(Monel)
Argon
Argon
Deoxised copper
Helium
Stable arc
Low fume
Stable and easy to control arc
Stable and easy to control arc
Can be used for copper-nickel
to steel
Increased heat input
Stable arc
Good penetration
Stable arc
Lower penetration
Stable arc
Manual operation
High speed automated welding
Stable arc
Good penetration
High speed automatic welding
Deeper penetration
Small concentrated HAZ
Used with continuous high
frequency AC
Good arc stability
Good cleaning action
Good penetration
Good arc stability
Deeper penetration
Stable arc
High speed welding
Nickel alloys
(Inconel)
Steel
Helium(75%)
/Argon(25%)
Argon
Helium
Argon
Helium
Magnesium alloys
Argon
Stainless steel
Argon
Titanium
Helium
Argon
Helium
Base material
BOC Consumable
C-Mn and low carbon steels
Low Alloy steels
1.25Cr/0.5Mo
2.5Cr/1Mo
Stainless Steel
304/304L
316/316L
309/309-C-Mn
321/Stabilised grades
BOC Mild steel TIG wire
Filler rod diameter (mm)
Thickness of metal (mm)
2
3
4
4 or 5
5 or 6
0.5 – 2
2 – 5
5 – 8
8 – 12
12 or more
Comweld CrMo1
Comweld CrMo2
Profill 308
Profill 316
Profill 309
Profill 347
BOC Smootharc Multiprocess 175 Operating manual
19
3.6 Tungsten electrode selection
Base metal type
Copper alloys,
Cu-NI alloys and
Nickel alloys
Mild Steels,
Carbon Steels,
Alloy Steels,
Stainless Steels
and Titanium
alloys
Thickness
range
Desired results
Welding
current
All
General purpose
DCSP
Electrode type
Shielding gas Tungsten performance characteristics
2% Thoriated
(EW-Th2)
75% Argon/
25% Helium
2% Ceriated
(EW-Ce2)
75% Argon/
25% Helium
Medium erosion rate
Low erosion rate. Wide current range. AC or DC.
No spitting. Consistent arc starts
Good stability
Low erosion rate. Wide current range. AC or DC.
No spitting. Consistent arc starts
Only thick
sections
Increase
penetration or
travel speed
DCSP
2% Ceriated
(EW-Ce2)
75% Argon/
25% Helium
All
General purpose
DCSP
2% Thoriated
(EW-Th2)
75% Argon/
25% Helium
2% Ceriated
(EW-Ce2)
75% Argon/
25% Helium
2% Lanthanated
(EWG-La2)
2% Ceriated
(EW-Ce2)
2% Lanthanated
(EWG-La2)
75% Argon/
25% Helium
75% Argon/
25% Helium
Helium
Only thick
sections
Increase
penetration or
travel speed
DCSP
Best stability at medium currents. Good arc
starts
Medium tendency to spit
Good stability
Best stability at medium currents. Good arc
starts
Medium tendency to spit
Medium erosion rate
Low erosion rate. Wide current range.  AC or DC.
No spitting Consistent arc starts
Good stability
Lowest erosion rate. Widest current range on
DC. No spitting. Best DC arc starts and stability
Low erosion rate. Wide current range. No
spitting. Consistent arc starts. Good stability
Lowest erosion rate. Highest current range. No
spitting. Best DC arc starts and stability
20
BOC Smootharc Multiprocess 175 Operating manual
Tungsten tip preparation
DCSP (EN) or DCRP (EP)
= Diameter
ACHP General Purpose
Flat
1/4–1/2x Dia
Max. ball
1x Dia
Taper length
2–3x Dia
Ball tip by arcing on clean metal at low current DCRP (EP) then slowly
increase current to form the desired ball diameter. Return setting to AC.
Tungsten grinding
Shape by grinding longitudinally (never
radially). Remove the sharp point to
leave a truncated point with a flat
spot. Diameter of flat spot determines
amperage capacity (See below). The
included angle determines weld bead
shape and size. Generally, as the
included angle increases, penetration
increases and bead width decreases.
Use a medium (60 grit or finer)
aluminium oxide wheel.
Tungsten extension
Gas Lens Parts
Standard Parts
General
purpose
3x Dia
General
purpose
3x Dia
Maximum
6x Dia
(in draft free areas)
Tungsten electrode tip shapes and current ranges
Thoriated, ceriated, and lanthanated tungsten electrodes do not ball
as readily as pure or zirconiated tungsten electrodes, and as such are
typically used for DCSP welding. These electrodes maintain a ground
tip shape much better than the pure tungsten electrodes. If used on
AC, thoriated and lanthanated electrodes often spit. Regardless of the
electrode tip geometry selected, it is important that a consistent tip
configuration be used once a welding procedure is established. Changes
in electrode geometry can have a significant influence not only on the
weld bead width, depth of penetration, and resultant quality, but also on
the electrical characteristics of the arc. Below is a guide for electrode tip
preparation for a range of sizes with recommended current ranges.
Electrode
diameter (mm)
Diameter arc
tip (mm)
Constant
included angle,
(degrees)
Current range
(A)
1.0
1.0
1.6
1.6
2.3
2.3
3.2
3.2
0.125
0.250
0.500
0.800
0.800
1.100
1.100
1.500
12
20
25
30
35
45
60
90
2 – 15
5 – 30
8 – 50
10 – 70
12 – 90
15 – 150
20 – 200
25 – 250
21
BOC Smootharc Multiprocess 175 Operating manual
3.7 Welding techniques
3.8 Torch movement during welding
TIG Welding techniques
Tungsten Without Filler Rod
Welding
direction
Welding
direction
Vertical
Welding Rod
60–75°
Shield gas
75°
Form pool
Nozzle
15–30°
Direction of travel
Tungsten With Filler Rod
Form pool
75°
75°
75°
Tungsten electrode
75°
The suggested electrode and welding rod angles for welding a bead on
plate are shown above. The same angles are used when making a butt
weld. The torch is held 60–75° from the metal surface. This is the 75°
same as
holding the torch 15–30° from the vertical.
Tilt torch
75°
15°
Tilt torch
75°
15°
Take special note that the rod is in the shielding gas during the
welding process.
75°
75°
Move torch to front of pool. Repeat.
15°
Add filler metal
75°
15°
75°
15°
Remove rod
Move torch to front of pool. Repeat.
15°
90°
22
BOC Smootharc Multiprocess 175 Operating manual
90°
70°
90°
70°
90°
90°
20°
70°
20°
20°
20°
20
20°
20°
20°
20°
75°
20°
75°
10°
15°
15°
10°
70°
70°90°
90°
10°
3.9Positioning torch tungsten for various weld90°
joints
Butt Weld and Stringer bead
Corner Joint
70°
°
70°
90°
20°
90°
20°
20°
75°15°
15°
‘T’ Joint
20-40
15°
20-40°
75°
75°
Lap Joint
20-40°
20-40°
20-40°
20°
20°
20°
75°
15°
15° 10°
15°
75°
15°
15°
10°
10°
75°
75°
30°
75°
75°
15°
10°
15°
75°
15°
20°
20°
75°
75°
75°
90° 70°
20°
20-40°
90°
20°
20°
70°
90°
90°
10°
15°
75°
15°
10°
90°
10°
75°
30°
30°
15°
30°
75°
15°
30°
15°
75°
22
ss
s
22
s
s s
r=
r =r =2
22
23
BOC Smootharc Multiprocess 175 Operating manual
s
s s
s
r=
s2
s
r=
r= 2
2
2
2
22
s
3.10 Joint preparation
s
2
s
s s s
r = r =r =
2 22
2
2
s s s
ss s
r r==r =
22 2
ss
r r==
22
2 2 32
33
ss s
22 2
ss
3
3 322
3
3
3
3 33
33 3
33
10°
10°
10°
33
0- S
0- SS 2
022
50°
50°
2-3.5
2-3.5
2-3.5
3
33 3
11
1
1
11
1
1
50°50°
50°
2-3.5
50°
50°
2-3.5
1 11
50°
50°
50°
2-3.550°
2-3.5
2-3.5
2-3.5
50°
50°
50°
2-3.5
2-3.5
2-3.5
~
~3
~
~33
~~
50°
2-3.5
2-3.5
50°
50°
~3
~
~3
~
~ 3~
All measurements in mm
50°50°
50°
~
~3
50°
50°
50°
~
3
~
~
~3
50°
50°
0-3
10°
10°
10°
~
~0-3
~~
~
4~
44
10°
10°
10°10°
10°
~
~
~40-3
4~ 40-3
~~
0-3
11 1
11
3-20
3-20
3-20
33
3-20
3-20
3-20
~
~~
~44
0-30-3
60°
0-3
10°
10°
60°
60°
10°
22
2
3-20
3-20
3-20
3-203-20
3-20
3-20
15-40
3-20
3-20
15-40
15-40
3-20
3-20
15-40
15-40
15-40
~
~5
~
~ ~5 5
~
~5
~
~5
~
~5
~
~5~
~5 5 20°
~~
20°
~
~~
~5520°
15-40
15-40
15-40
12 1212
2
2
2 22
22 55
16
1616
1.5-3
1.5-3
1.5-3
50°50°
50°
16
5
5
5
16 1616
5 55
161616
~ 15°
15°
~~ 15°
~ 15°
15°
~ ~15°
1616
33
3
33
3
20°
20°
20°
~
~ 6~
~~
66
~
1.5-3
50°
1.5-3
1.5-3 2 22
1.5-3
1.5-3
50°
50°
16
16
~
~~ 62-3
~
~~
6 62-3
20°
20°
1.5-3
1.5-3
1.5-3
5
5
55
3
3
55 5
3
55
1
50°
50°
50°
1.5-3
1.5-3
50°
1.5-350°
2
~ 15°
~ ~15°
15°
~15°
~~15°
15°
~~15°
15°
8-40
8-40
8-40
2
8-40
8-40
8-40
Offset2 2
2
22
1.5-3
1.5-3
1.5-3
1.5-3
1.5-3
8-40
6-20
6-20
8-40
8-40
2
~ 15°
~ 15°
~ 15°
6-20
6-20
6-20
11
2 22
1.5-3
1.5-3
1.5-3
6-20
6-20
6-20
6-206-20
6-20
1.5-3
2
1.5-3
1.5-3
50°
22
50°
50°
11 1
121216
16
16
22 2
1
1 11
121212
60°
60°
2-32-3
2-3
~
~6
20°20°
20°
~
~6
~
~6
1
1.5-3
50°
1.5-3
50°
50°
1.5-3
2
60°
~
60°
~60°
6
2-3
2-3
2-3
~
~66
~~
15-40
15-40
15-40
1
11
1.5-3
1.5-3
1.5-3
12
1
6-20
6-20
6-20
12
12
2-3
2-3
2-3
60°
10°10°
10°
60°
60°
2-3
10°
10°
10°
20°
20° 2-3
20°
2-360°60°
60°
10°
10°
20°
20°
20°
~
~ 5~
~~
~5 5
11
1.5-3
1.5-3
1.5-3
12
1212
2
22
0-3
0-3
2-3
2-3
2-3
60°
60°
60°
~
~ 5 10°
~
~ 55
~~
10°
10°
6-20
6-20
6-20
12
12
12
~
~ 4 10°
10°
~
~ 410°
0-3
3
3 33
1
50°
50°
10°
10° 0-3
0-3
0-3
~
~4
3
0- S
2
0- S
0- S
2
50°
2
50°
50°
0- 0-S0- S S
2 22
22
50°
3
3
33
0- SS
0-0- S
2
22
SS S
50°
00-0-50°
50°
2
222-3.5
SS
2-3.5
0-0-2-3.5
~
~4
~
~44
~~
10°
10°
10°
0-3
0-3
0-3
~
~
4
~
~
~
~10°
44
Roll direction
8-408-40
8-40
8-40
8-40
8-40
8-40
8-40
24
BOC Smootharc Multiprocess 175 Operating manual
Condition
Long arc length
Result
Undercut
Porosity
Air
Air
Wide bead
profile
Acute angle
Loss of gas
coverage
Air
Oxides
Angular
mis-alignment
Unsymmetrical bead
profile
Mis-alignment
Incomplete
penetration
Filler rod removed
from gas shield
Oxides
Rod
movement
Tungsten inclusions
Electrode contact
with the weld pool
Tungsten inclusions
Oxides
BOC Smootharc Multiprocess 175 Operating manual
25
4.0Manual Metal Arc Welding Process
(MMAW)
TIG Welding techniques
Flux Covering
Core Wire
Weld Metal
Slag
Arc
Weld Pool
Workpiece
4.1Introduction
Arc welding, although in the past principally the tool of tradesmen
and fabricators, has in recent years found increasing usage with small
workshops, farmers, handyman-hobbyists amongst others. This has
been brought about by the introduction of low-cost portable arc welding
machines and the ready availability of small diameter electrodes and
thinner section construction materials. Provided the operator is familiar
with the basic principles and techniques, arc welding can be a fast,
efficient and safe method of joining metals.
The main purpose of this manual is to help the welder with limited
experience to obtain a better understanding of the process, and to
acquire a reasonable degree of proficiency in the least possible time.
Even welders with some experience will benefit from the information in
this manual.
4.2Process
Manual Metal Arc welding is the process of joining metals where an
electric arc is struck between the metal to be welded (parent metal) and
a flux-coated filler wire (the electrode). The heat of the arc melts the
parent metal and the electrode which mix together to form, on cooling, a
continuous solid mass.
Before arc welding can be carried out, a suitable power source is
required. Two types of power sources may be used for arc welding, direct
current (DC) or alternating current (AC).
The essential difference between these two power sources is that, in the
case of DC, the current remains constant in magnitude and flows in the
same direction. Similarly, the voltage in the circuit remains constant in
magnitude and polarity (i.e. positive or negative).
In the case of AC however, the current flows first in one direction and
then the other. Similarly, the voltage in the circuit changes from positive
to negative with changes in direction of current flow. This complete
reversal is called a ‘half cycle’ and repeats as long as the current
flows. The rate of change of direction of current flow is known as the
‘frequency’ of the supply and is measured by the number of cycles
completed per second. The standard frequency of the AC supply in
Australia is 50 Hz (Hertz).
26
BOC Smootharc Multiprocess 175 Operating manual
Installation for MMA process
4.3 Welding Machine
4.4 Welding Technique
The most important consideration when contemplating the use of arc
welding for the first time is the purchase of a suitable welding machine.
Successful welding depends on the following factors:
BOC supplies a popular range of arc welding machines. Machines
range from small portable welders that operate from standard 240
Volt household power to heavy-duty welders used by the largest steel
fabricators.
Basic Welding Machine and Cables
The choice of welding machine is based mostly on the following factors:
• primary voltage, e.g. 240 Volt or 380 Volt
• output amperage required, e.g. 140 amps
• output required, e.g. AC or DC +/• duty cycle required, e.g. 35% @ 140 amps
• method of cooling, e.g. air‑cooled or oil‑cooled method of output
amperage control, e.g. tapped secondary lugs
• or infinitely variable control.
For example, the Smootharc Multiprocess 175 connects to 240 Volt supply
(15 amps Input), has an output of 175 amps DC @ 35% duty cycle.
Having decided on a welding machine, appropriate accessories are
required. These are items such as welding cables, clamps, electrode
holder, chipping hammer, helmet, shaded and clear lenses, scull cap,
gloves and other personal protective equipment.
BOC stocks a huge range of personal protective equipment. This
combined with BOC’s extensive network ensures fast reliable service
throughout the South Pacific.
• selection of the correct electrode
• selection of the correct size of the electrode for the job
• correct welding current
• correct arc length
• correct angle of electrode to work
• correct travel speed
• correct preparation of work to be welded.
4.5 Electrode Selection
As a general rule the selection of an electrode is straight forward, in that
it is only a matter of selecting an electrode of similar composition to the
parent metal. It will be found, however, that for some metals there is a
choice of several electrodes, each of which has particular properties to
suit specific classes of work. Often, one electrode in the group will be
more suitable for general applications due to its all round qualities.
The table (page 27) shows just a few of the wide range of electrodes
available from BOC with their typical areas of application.
For example, the average welder will carry out most fabrication using
mild steel and for this material has a choice of various standard BOC
electrodes, each of which will have qualities suited to particular tasks.
For general mild steel work, however, BOC Smootharc 13 electrodes will
handle virtually all applications. BOC Smootharc 13 is suitable for welding
mild steel in all positions using AC or DC power sources. Its easy-striking
characteristics and the tolerance it has for work where fit-up and plate
surfaces are not considered good, make it the most attractive electrode
of its class. Continuous development and improvement of BOC Smootharc
13 has provided in-built operating qualities which appeals to the
BOC Smootharc Multiprocess 175 Operating manual
beginner and experienced operator alike. For further recommendations
on the selection of electrodes for specific applications, see table page 27.
size. The following table gives the recommended maximum size of
electrodes that may be used for various thicknesses of section.
Electrodes and Typical Applications
Recommended Electrode Sizes
Name
Average Thickness of Plate or Section Max. Recommended Electrode Dia.
AWS Class. Application
BOC Smootharc 13 E6013
BOC Smootharc 24 E7024
BOC Smootharc 18 E7018-1
BOC Smootharc S
308L
E308L
BOC Smootharc S
316L
E316L
BOC Smootharc S
309L
E309L
A premium quality electrode for general
structural and sheet metal work in all
positions including vertical down using low
carbon steels
An iron powder electrode for high speed
welding for H-V fillets and flat butt joints.
Medium to heavy structural applications in
low carbon steels
A premium quality all positional hydrogen
controlled electrode for carbon steels in
pressure vessel applications and where high
integrity welding is required and for freemachining steels containing sulphur
Rutile basic coated low carbon electrodes for
welding austenitic stainless steel and difficult
to weld material
Rutile basic coated low carbon electrode
for welding mild steel to stainless steel and
difficult to weld material
Electrode Size
The size of the electrode is generally dependent on the thickness of the
section being welded, and the larger the section the larger the electrode
required. In the case of light sheet the electrode size used is generally
slightly larger than the work being welded. This means that if 1.5 mm
sheet is being welded, 2.0 mm diameter electrode is the recommended
≤1.5 mm
2.0 mm
1.5–2.0 mm
2.5 mm
2.0–5.0 mm
3.15 mm
5.0–8.0 mm
4.0 mm
≤8.0 mm
5.0 mm
27
Welding Current
Correct current selection for a particular job is an important factor in arc
welding. With the current set too low, difficulty is experienced in striking
and maintaining a stable arc. The electrode tends to stick to the work,
penetration is poor and beads with a distinct rounded profile will be
deposited.
Excessive current is accompanied by overheating of the electrode. It will
cause undercut, burning through of the material, and give excessive
spatter. Normal current for a particular job may be considered as the
maximum which can be used without burning through the work, overheating the electrode or producing a rough spattered surface, i.e. the
current in the middle of the range specified on the electrode package is
considered to be the optimum.
In the case of welding machines with separate terminals for different
size electrodes, ensure that the welding lead is connected to the correct
terminal for the size electrode being used. When using machines with
adjustable current, set on the current range specified.
The limits of this range should not normally be exceeded.
28
BOC Smootharc Multiprocess 175 Operating manual
The following table shows the current ranges generally recommended for
BOC Smootharc 13.
Generally Recommended Current Range for BOC Smootharc 13
Size of Electrode (mm)
Current Range (Amp)
2.5
60–95
3.2
110–130
4.0
140–165
5.0
170–260
Arc Length
To start the arc, the electrode should be gently scraped on the work until
the arc is established. There is a simple rule for the proper arc length; it
should be the shortest arc that gives a good surface to the weld. An arc
too long reduces penetration, produces spatter and gives a rough surface
finish to the weld. An excessively short arc will cause sticking of the
electrode and rough deposits that are associated with slag inclusions.
For downhand welding, it will be found that an arc length not greater
than the diameter of the core wire will be most satisfactory. Overhead
welding requires a very short arc, so that a minimum of metal will be lost.
Certain BOC electrodes have been specially designed for ‘touch’ welding.
These electrodes may be dragged along the work and a perfectly sound
weld is produced.
Electrode Angle
The angle which the electrode makes with the work is important to
ensure a smooth, even transfer of metal. The recommended angles
for use in the various welding positions are covered later.
Correct Travel Speed
The electrode should be moved along in the direction of the joint being
welded at a speed that will give the size of run required. At the same
time the electrode is fed downwards to keep the correct arc length
at all times. As a guide for general applications the table below gives
recommended run lengths for the downhand position.
Correct travel speed for normal welding applications varies between
approximately 125–375 mm per minute, depending on electrode size,
size of run required and the amperage used.
Excessive travel speeds lead to poor fusion, lack of penetration, etc.
Whilst too slow a rate of travel will frequently lead to arc instability, slag
inclusions and poor mechanical properties.
Run Length per Electrode – BOC Smootharc 13
Electrode Size (mm)
Electrode Length (mm)
Run Length (mm)
Min. to Max.
4.0
350
175 to 300
3.2
350
125 to 225
2.5
350
100 to 225
Correct Work Preparation
The method of preparation of components to be welded will depend on
equipment available and relative costs. Methods may include sawing,
punching, shearing, lathe cut-offs, flame cutting and others. In all
cases edges should be prepared for the joints that suit the application.
The following section describes the various joint types and areas
of application.
BOC Smootharc Multiprocess 175 Operating manual
29
Butt Welding
FACE REINFORCEMENT
WELD FACE
ROOT FACE
ROOT GAP
4.6 Types of Joints
Double ‘V’ Butt Weld
Butt Welds
A butt weld is a weld made between two plates so as to give continuity
of section. Close attention must be paid to detail in a butt weld to ensure
that the maximum strength of the weld is developed. Failure to properly
prepare the edges may lead to the production of faulty welds, as correct
manipulation of the electrode is impeded.
Two terms relating to the preparation of butt welds require explanation
at this stage. They are:
Used on plate of 12 mm and over in thickness when welding
can be applied from both sides. It allows faster welding and
greater economy of electrodes than a single ‘V’ preparation on
the same thickness of steel and also has less of a tendency to
distortion as weld contraction can be equalised.
Butt Weld with Backing Material
When square butt welds or single ‘V’ welds cannot be welded
from both sides it is desirable to use a backing bar to ensure
complete fusion.
Single ‘U’ Butt Weld
• Root Face: the proportion of the prepared edge that has not been
bevelled.
• Root Gap: the separation between root
faces of the parts to be joined.
Used on thick plates an alternative to a single ‘V’ preparation. It
has advantages as regards speed of welding. It takes less weld
metal than a single ‘V’, there is less contraction and therefore a
lessened tendency to distortion. Preparation is more expensive
than in the case of a ‘V’, as machining is required. The type of
joint is most suitable for material over 40 mm in thickness.
Various types of butt welds are in common use and their suitability for
different thickness of steel are described as follows:
Double ‘U’ Butt Weld
For use on thick plate that is accessible for welding from both
sides. For a given thickness it is faster, needs less weld metal
and causes less distortion than a single ‘U’ preparation.
Square Butt Weld
The edges are not prepared but
are separated slightly to allow fusion through the full thickness
of the steel. Suitable for plate up
to 6 mm in thickness.
Horizontal Butt Weld
The lower member in this case is bevelled to approximately 15°
and the upper member 45°, making an included angle of 60°.
This preparation provides a ledge on
the lower member, which tends
to retain the molten metal.
Single ‘V’ Butt Weld
This is commonly used for plate up to 16 mm in thickness and on
metal of greater thickness where access
WELD BEADS
is available from only one side.
WELD BEADS
LAYERS
ELECTRODE
LAYERS
ELECTRODE
70˚ - 85˚
WELD BEADS
WELDBEADS
POOL
WELD
SLAG
WELD METAL
70˚ - 85˚
WELD BEADS
ARC
WELD POOL
SLAG
WELD METAL
ARC
30
BOC Smootharc Multiprocess 175 Operating manual
Welding Progression Angle
Electrode
70–85˚
Weld Metal
Slag
Arc
Weld Pool
Workpiece
Direction of Welding
General notes on Butt Welds
The first run in a prepared butt weld should be deposited with an
electrode not larger than 4.0 mm. The angle of the electrode for the
various runs in a butt weld is shown.
It is necessary to maintain the root gap by tacking at intervals or by other
means, as it will tend to close during welding.
All single ‘V’, single ‘U’ and square butt welds should have a backing run
deposited on the underside of the joint; otherwise 50% may be deducted
from the permissible working stress of the joint.
Before proceeding with a run on the underside of a weld it is necessary
to remove any surplus metal or under penetration that is evident on that
side of the joint.
Butt welds should be overfilled to a certain extent by building up
the weld until it is above the surface of the plate. Excessive build-up,
however, should be avoided.
In multi-run butt welds it is necessary to remove all slag, and surplus
weld metal before a start is made on additional runs; this is particularly
important with the first run, which tends to form sharp corners that
cannot be penetrated with subsequent runs. Electrodes larger than 4.0
mm are not generally used for vertical or overhead butt welds.
The diagrams following indicate the correct procedure for welding thick
plate when using multiple runs.
Electrode Angle for 1st and 2nd Layers
WELD BEADS
WELD BEADS
LAYERS
ELECTRODE
LAYERS
ELECTRODE
Electrode Angle for Subsequent Layers
WELD BEADS
WELD BEADS
WELD POOL
SLAG
WELD POOL
SLAG
WELD METAL
WELD METAL
DIRECTION O
LAYERS
LAYERS
DIRECTION OF
BOC Smootharc Multiprocess 175 Operating manual
4.7 Fillet Welds
A fillet weld is approximately triangular in section, joining two surfaces
not in the same plane and forming a lap joint, tee joint or corner joint.
Joints made with fillet welds do not require extensive edge preparation,
as is the case with butt welded joints, since the weld does not
necessarily penetrate the full thickness of either member. It is important
that the parts to be joined be clean, close fitting, and that all the edges
on which welding is to be carried out are square. On sheared plate it
is advisable to entirely remove any ‘false cut’ on the edges prior to
welding. Fillet welds are used in the following types of joints:
‘T’ Joints
A fillet weld may be placed either on one or both
sides, depending on the requirements of the work.
The weld metal should fuse into or penetrate the
corner formed between the two members. Where
possible the joint should be placed in such a position
as to form a “Natural ‘V’ fillet” since this is the easiest
and fastest method of fillet welding.
Lap Joints
In this case, a fillet weld may be placed either on one
or both sides of the joint, depending on accessibility
and the requirements of the joint. However, lap joints,
where only one weld is accessible, should be avoided
where possible and must never constitute the joints
of tanks or other fabrications where corrosion is likely
to occur behind the lapped plates. In applying fillet
welds to lapped joints it is important that the amount
of overlap of the plates be not less than five times the
thickness of the thinner part. Where it is required to
preserve the outside face or contour of a structure,
one plate may be joggled.
31
Corner Joints
The members are fitted as shown, leaving a ‘V’shaped groove in which a fillet weld is deposited.
Fusion should be complete for the full thickness
of the metal. In practice it is generally necessary
to have a gap or a slight overlap on the corner.
The use of a 1.0–2.5 mm gap has the advantage of
assisting penetration at the root, although setting
up is a problem. The provision of an overlap largely
overcomes the problem of setting up, but prevents
complete penetration at the root and should therefore
be kept to a minimum, i.e. 1.0–2.5 mm.
The following terms and definitions are important in specifying and
describing fillet welds.
Leg Length
A fusion face of a fillet weld, as shown below. All specifications for fillet
weld sizes are based on leg length.
Throat Thickness
A measurement taken through the centre of a weld from the root to the
face, along the line that bisects the angle formed by the members to
be joined.
Effective throat thickness is a measurement on which the strength of
a weld is calculated. The effective throat thickness is based on a mitre
fillet (concave Fillet Weld), which has a throat thickness equal to 70% of
the leg length. For example, in the case of a 20 mm fillet, the effective
throat thickness will be 14 mm.
32
BOC Smootharc Multiprocess 175 Operating manual
Convex Fillet Weld
Concave Fillet Weld
CONVEXITY
CONVEXITY
ACTUAL THROAT
ACTUAL THROAT
LEG
LENGH LEG
LENGH
EFFECTIVE THROAT
EFFECTIVE THROAT
LEG
CONCAVITY
SIZE
CONCAVITY
ACTUAL THROAT
AND EFFECTIVE
ACTUAL THROAT
THROAT
AND EFFECTIVE
THROAT
LEG
SIZE
SIZE LEG
SIZE LEG
THEORETICAL THROAT
THEORETICAL THROAT
THEORETICAL THROAT
THEORETICAL THROAT
Convex Fillet Weld
A fillet weld in which the contour of the weld metal lies outside a straight
line joining the toes of the weld. A convex fillet weld of specified leg
length has a throat thickness in excess of the effective measurement.
Concave Fillet Weld
A fillet in which the contour of the weld is below a straight line joining
the toes of the weld. It should be noted that a concave fillet weld of
a specified leg length has a throat thickness less than the effective
throat thickness for that size fillet. This means that when a concave fillet
weld is used, the throat thickness must not be less than the effective
measurement. This entails an increase in leg length beyond the
specified measurement.
The size of a fillet weld is affected by the electrode size, welding speed
or run length, welding current and electrode angle. Welding speed and
run length have an important effect on the size and shape of the fillet,
and on the tendency to undercut.
Insufficient speed causes the molten metal to pile up behind the arc and
eventually to collapse. Conversely, excessive speed will produce a narrow
irregular run having poor penetration, and where larger electrodes and
high currents are used, undercut is
likely to occur.
Selection of welding current is important. If it is too high the weld surface
will be flattened, and undercut accompanied by excessive spatter is
likely to occur. Alternatively, a current which is too low will produce a
rounded narrow bead with poor penetration at the root. The first run in
the corner of a joint requires a suitably high current to achieve maximum
penetration at the root. A short arc length is recommended for fillet
welding. The maximum size fillet which should be attempted with one
pass of a large electrode is 8.0 mm. Efforts to obtain larger leg lengths
usually result in collapse of the metal at the vertical plate and serious
undercutting. For large leg lengths multiple run fillets are necessary.
These are built up as shown below. The angle of the electrode for various
runs in a downhand fillet weld is shown below.
Recommended Electrode Angles for Fillet Welds
1st Run
2nd Run
3rd Run
Multi-run Fillet
Fillet Weld Data
Nominal
Fillet Size (mm)
Minimum Throat
Thickness (mm)
Plate Thickness
(mm)
Electrode Size
(mm)
5.0
3.5
5.0–6.3
3.2
6.3
4.5
6.3–12
4.0
8.0
5.5
8.0–12 & over
4.0
10.0
7.0
10 & over
4.0
Multi-run horizontal fillets have each run made using the same run
lengths (run length per electrode table). Each run is made in the same
direction, and care should be taken with the shape of each, so that it has
equal leg lengths and the contour of the completed fillet weld
is slightly convex with no hollows in the face.
BOC Smootharc Multiprocess 175 Operating manual
33
Recommended Angles for Overhead Fillet Welds
15˚
45˚
30˚
Vertical fillet welds can be carried out using the upwards or downwards
technique. The characteristics of each are: upwards – current used is low,
penetration is good, surface is slightly convex and irregular. For multiple
run fillets large single pass weaving runs can be used. Downwards –
current used is medium, penetration is poor, each run is small, concave
and smooth (only BOC Smootharc 13 is suitable for this position).
The downwards method should be used for making welds on thin
material only. Electrodes larger than 4.0 mm are not recommended for
vertical down welding. All strength joints in vertical plates 10.0 mm thick
or more should be welded using the upward technique. This method is
used because of its good penetration and weld metal quality. The first
run of a vertical up fillet weld should be a straight sealing run made with
3.15 mm or 4.0 mm diameter electrode. Subsequent runs for large fillets
may be either numerous straight runs or several wide weaving runs.
4.8 Typical Defects Due to Faulty Technique
Manual metal arc welding, like other welding processes, has welding
procedure problems that may develop which can cause defects in the
weld. Some defects are caused by problems with the materials. Other
welding problems may not be foreseeable and may require immediate
corrective action. A poor welding technique and improper choice of
welding parameters can cause weld defects. Defects that can occur
when using the shielded metal arc welding process are slag inclusions,
wagon tracks, porosity, wormhole porosity, undercutting, lack of fusion,
overlapping, burn through, arc strikes, craters, and excessive weld
spatter. Many of these welding technique problems weaken the weld
and can cause cracking. Other problems that can occur which can
reduce the quality of the weld are arc blow, finger nailing, and improper
electrode coating moisture contents.
Correct selection of electrodes is important for vertical welding.
In overhead fillet welds, careful attention to technique is necessary
to obtain a sound weld of good profile. Medium current is required for
best results. High current will cause undercutting and bad shape of
the weld, while low current will cause slag inclusions. To produce a
weld having good penetration and of good profile, a short arc length is
necessary. Angle of electrode for overhead fillets is illustrated above.
Defects caused by welding technique
Slag Inclusions
SLAG INCLUSIONS
Slag inclusions occur when slag particles are trapped inside the weld
metal which produces a weaker weld. These can be caused by:
• erratic travel speed
• too wide a weaving motion
• slag left on the previous weld pass
• too large an electrode being used
• letting slag run ahead of the arc.
34
BOC Smootharc Multiprocess 175 Operating manual
This defect can be prevented by:
• a uniform travel speed
• a tighter weaving motion
• complete slag removal before welding
• using a smaller electrode
• keeping the slag behind the arc which is done by shortening the arc,
increasing the travel speed, or changing the electrode angle.
• using a travel speed slow enough so that the weld metal can
completely fill all of the melted out areas of the base metal.
Lack of Fusion
Undercutting
LACK OF FUSION
Lack of fusion is when the weld metal is not fused to the base metal.
This can occur between the weld metal and the base metal or between
passes in a multiple pass weld. Causes of this defect can be:
UNDERCUTTING
Undercutting is a groove melted in the base metal next to the toe or
root of a weld that is not filled by the weld metal. Undercutting causes a
weaker joint and it can cause cracking. This defect is caused by:
• excessive welding current
• too long an arc length
• excessive weaving speed
• excessive travel speed.
On vertical and horizontal welds, it can also be caused by too large
an electrode size and incorrect electrode angles. This defect can be
prevented by:
• choosing the proper welding current for the type and size of electrode
and the welding position
• holding the arc as short as possible
• pausing at each side of the weld bead when a weaving technique
is used
• excessive travel speed
• electrode size too large
• welding current too low
• poor joint preparation
• letting the weld metal get ahead of the arc.
Lack of fusion can usually be prevented by:
• reducing the travel speed
• using a smaller diameter electrode
• increasing the welding current
• better joint preparation
• using a proper electrode angle.
BOC Smootharc Multiprocess 175 Operating manual
5.0 General Welding Information
5.1 Recommended Welding Parameters for MIG/MAG
Argoshield Light
Indicative
Welding Parameters
Dip Transfer
Material thickness (mm)
1–1.6
2
3
4
3
Welding position
Horizontal /
Vertical
Horizontal /
Vertical
Horizontal /
Vertical
Horizontal /
Vertical
Horizontal
Wire diameter (mm)
0.8–0.9
0.8–0.9
0.8–0.9
0.9–1.0
0.8
Current (amps)
45–80
60–100
80–120
80–150
160–180
Voltage (volts)
14–16
16–17
16–18
16–18
23–25
Wire feed speed (m/min)
3.5–5.0
4.0–7.0
4.0–7.0
4.0–7.0
7.5–9.0
Gas rate flow (L/min)
15
15
15
15
15
Travel speed (mm/min)
350–500
350–500
320–500
280–450
800–1000
Spray
Transfer
Stainshield (Aus) or Stainshield Light (NZ)
Indicative
Welding Parameters
Dip Transfer
Material thickness (mm)
4
6
8
Welding position
Horizontal /
Vertical
Horizontal /
Vertical
Horizontal /
Vertical
Wire diameter (mm)
0.9–1.0
0.9–1.0
0.9–1.0
Current (amps)
100–125
120–150
120–150
Voltage (volts)
17–19
18–20
18–20
Wire feed speed (m/min)
5.0–6.5
6.0–7.5
6.0–8.0
Gas rate flow (L/min)
15
15
18
Travel speed (mm/min)
400–600
280–500
280–450
35
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BOC Smootharc Multiprocess 175 Operating manual
6.0 Correct Application Techniques
Electrical stickout
C
S
V
A
E
Contact Tube Setback
Standoff Distance
Visible Stickout
Arc length
Electrical Stickout
Gas Nozzle
Contact Tube
C
Consumable
S
Electrode
V
E
A
Workpiece
Correct Application Techniques
Direction of welding.
MIG/MAG welding with solid wires takes place normally with a push
technique. The welding torch is tilted at an angle of 10° towards the
direction of welding. (Push technique)
Flux cored welding with cored wires takes place normally with the drag
technique. The welding torch is tilted at an angle of 10° away from the
direction of welding. For all other applications the torch angle remains
the same.
10°
0–15°
The influence of changing the torch angle and the welding direction on
the weld bead profile can be seen below.
90°
90°
Torch position for butt welds
Torch perpendicular to workpiece narrow bead width with increased
reinforcement.
When welding butt welds the torch should be positioned within the
centre of the groove and tilted at an angle of ±15° from the vertical
plane. Welding is still performed in the push technique.
0–15°
10°
45°
45°
Torch positioned at a drag angle of 10° narrow bead with excessive
reinforcement.
BOC Smootharc Multiprocess 175 Operating manual
Electrical stickout
Short
Short
Travel speed
Normal
Normal
Long
Long
Torch position for fillet welds
When welding fillet welds the torch should be positioned at an angle of
45° from the bottom plate with the wire pointing into the fillet corner.
Welding is still performed in the push technique.
Electrical stickout
The electrical stickout is the distance between the end of the contact
tip and the end of the wire. An increase in the electrical stickout results
in an increase in the electrical resistance. The resultant increase in
temperature has a positive influence in the melt-off rate of the wire that
will have an influence on the weldbead profile.
Influence of the change in electrical stickout length on the weldbead
profile.
The travel speed will have an influence on the weldbead profile and the
reinforcement height.
If the travel speed is too slow a wide weldbead with excessive rollover
will result. Contrary if the travel speed is too high a narrow weldbead
with excessive reinforcement will result.
Slow
Normal
Fast
Slow
Normal
Fast
37
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BOC Smootharc Multiprocess 175 Operating manual
7.0 Package Contents
Front Panel of Multiprocess 175
Multifunctional data display
MMA / LIFT TIG / MIG
Wire Inch
VRD / 2T / 4T switch
Data selection
Multifunctional data adjustment
Package consists of the following:
• Power source
• Work return lead
• MMA electrode holder and cable
• BOC 17 series TIG torch
• Binzel MB15AK MIG/MAG torch
• Regulator
• Gas hose
• Spare feed rolls
• Operating manual
BOC Smootharc Multiprocess 175 Operating manual
8.0Smootharc Multiprocess 175 Installation
Installation for MIG/MAG process
A
B
C
8.1 Installation for MIG/MAG process
1 Connect the gas cylinder to the regulator. Select correct shielding gas
for the application.
2 Insert the earth return lead connection into the front panel.
3 Fit the wire spool to the machine. Select correct welding wire for
application.
4 Select the appropriate feed roller to suit the wire being used
-- This machine comes complete with two types of wire feed rollers
-- V groove for use with solid carbon manganese and stainless steels
-- U groove for use with soft wires such as aluminium
5 Loosen the wire feed tension screws and insert the wire. Re fit and
tension rollers ensuring the wire is gripped sufficiently so as not to
slip but avoid over tightening as this can affect feed quality and cause
wire feed components to wear rapidly.
6 Fit and tighten the torch on the output connection [A]. Ensure correct
torch liner and contact tip are selected.
7 Select the correct polarity for the type of wire used as indicated on
the consumable packaging. This is achieved by swapping the polarity
terminal wires. For most solid wires the terminal should be set as
torch positive.
8 For torch positive, plug the short mechanical connector (link plug) [B]
on the front panel into the positive (+) terminal and the work return
lead [C] into the negative (-) terminal.
9 For torch negative, couple the short mechanical connector [B] into the
terminal marked negative (-), and the work return lead [C] into the
positive (+) terminal.
39
40
BOC Smootharc Multiprocess 175 Operating manual
Installation for TIG setup
C
B
Installation for MMA process
A
B
D
A
C
8.2 Installation for TIG setup
8.3 Installation for MMA process
1 Connect the gas cylinder to the regulator. Select correct shielding gas
for the application.
1 Connect the electrode holder [A] to the positive (+) of the machine
and fasten it clockwise tightly.
2 Connect the dinse plug [A] of the TIG torch to negative (-) of the front
panel, and fasten it clockwise.
2 Connect the work return lead [B] into the negative (-) of the machine
and fasten it clockwise.
3 Connect the electrical lead of the TIG torch to the relative interfaces of
panel and fasten the screw [B].
3 Please note that for manual metal arc (MMA) welding the electrode
holder can be switched to the negative pole of the welding machine
if so required by the specification of the electrode.
4 Connect one end of the work return lead [C] to positive (+) of the
front panel, and fasten it clockwise. Connect the other end of the
clamp to the work piece.
5 The short mechanical connector (link plug) [D] should remain
hanging free.
4 The short mechanical connector (link plug) [C] should remain
hanging free.
BOC Smootharc Multiprocess 175 Operating manual
9.0 Control panels
Front Panel of Multiprocess 175
Multifunctional data display
MMA / LIFT TIG / MIG
Wire Inch
VRD / 2T / 4T switch
Data selection
Multifunctional data adjustment
Data selection (effective under MIG mode)
Multifunctional data adjustment
Coarse adjustments made by pressing and turning the knob. Big
regulating rate and high speed
Fine adjustments made by only turning the knob. Small regulating rate
and low speed.
9.1 Polarity selection
Polarity selection can be reversed when welding in MIG/MAG mode.
This is important for certain types of self-shielded flux cored wires. This
can be achieved by switching the work return lead to the positive (+)
terminal and the short mechanical connector (link plug) to the negative
(-) terminal for a DC electrode negative polarity setting.
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BOC Smootharc Multiprocess 175 Operating manual
10.0 Smootharc Multiprocess 175 Operation
Illustration 1. Start-up display
Illustration 2. MMA mode – VRD enabled
Illustration 3. MMA mode – VRD disabled
10.1 Starting up
Switch on the welding power source. The front panel display will light up
as shown in Illustration 1. After the Multifunctional Data display (or any
key or knob on front panel) flashes for 5 seconds, the machine enters
into the welding mode that was saved in the last shutdown.
10.2 Operation for MMA mode
Press the MMA/LIFT TIG/MIG switch to MMA. The MMA indicator light will
illuminate.
In the MMA mode, press the VRD/2T/4T switch. The VRD function is
enabled when the indicator light is on.
Multifunctional Data display shows the preset current (A) 80A shown in
Illustration 2.
Adjusting the Multifunctional Data adjustment will change the welding
current during the welding process. The welding current range is
10‑175A.
Three seconds after changing the welding parameters, the
Multifunctional Data display will flash once to indicate that the setting
has been saved. If the parameters are unchanged this setting will remain
as such even after restarting the machine.
The machine has the ability to display the arc voltage during MMA
welding (23.2V at 80A as shown in Illustration 4). The arc voltage will
only be displayed during welding and for five seconds after completion
of welding when the display will revert back to the preset display
amperage.
Illustration 4. MMA mode – Display status when welding
BOC Smootharc Multiprocess 175 Operating manual
Illustration 5. Lift TIG mode – Current preset
Illustration 6. Lift TIG mode – Status when welding is performed
Illustration 7. Lift TIG mode – Status after welding is stopped
10.3 Operation instruction under LIFT TIG mode
Press the MMA/LIFT TIG/MIG switch to LIFT TIG. The LIFT TIG indicator light
will illuminate.
The welding mode (2T/4T)* can be selected by depressing the
VRD/2T/4T. The selected mode will illuminate.
The illustrations above indicate that the LIFT TIG mode and 2T NORMAL
has been selected.
The welding amperage can be adjusted by turning the Multifunctional
Data adjustment. In the illustrations above it is selected at 80A.
Welding amperage can be adjusted whilst welding and the welding
current range is 10-175A.
If settings are unchanged for three seconds the Multifunctional Data
display will flash once to indicate that the setting has been saved and
these will be retained, and displayed when the machine restarts.
* 2T is non-latched trigger operation (press and hold to keep welding
and let go to stop). 4T is latched trigger operation (click trigger to start
welding and click again to stop).
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BOC Smootharc Multiprocess 175 Operating manual
Illustration 8. MIG mode – Preset voltage
10.4 Operation instruction under MIG mode
Press the MMA/LIFT TIG/MIG switch to MIG. The MIG indicator light will
illuminate.
In MIG mode, the wire can be fed through the system by pressing the
Wire Inch button.
To feed the wire through the torch the Wire Inch button has to be
pressed to feed the wire. To stop feeding the wire release the button.
In both illustrations shown above the Multifunctional Data display shows
a preset voltage of 19.5V and a wire feed speed of 05.0m per minute.
The welding mode (2T/4T)* can be selected by depressing the
VRD/2T/4T. The selected mode will illuminate. (Refer to the section
on MIG Fundaments in this manual for an explanation for 2T and 4T
operation).
The welding parameters can be adjusted during welding by turning the
Multifunctional Data adjustment. This action will synergically change
both parameters (volts and wire feed speed).
The synergic welding parameter range is 17.5V 2.0 m/min to
25.8V 12 m/min.
* 2T is non-latched trigger operation (press and hold to keep welding
and let go to stop). 4T is latched trigger operation (click trigger to start
welding and click again to stop).
Illustration 9. MIG mode – Wire Check
BOC Smootharc Multiprocess 175 Operating manual
Illustration 10. MIG mode – Fine adjustment of voltage range
Data selection
Use of the Data Selection button (MIG mode only)
Pressing the Data Selection button will enable you to switch between:
1 Arc welding adjustment mode
2 Inductance
3 Preset voltage and wire speed
By pressing the Data Selection button the Multifunctional Data display
will change according to the welding parameter function mode that
can be changed. In Illustration 10, it displays the arc voltage and the
adjustment that can be done. In this mode the arc voltage is adjustable
and the adjustment range of the preset value is ±20%.
When the Data Selection button is pressed again the Multifunctional
Data Display will change to display the inductance as shown in
Illustration 11. In this mode the inductance is adjustable and its
adjustment range is ±10%.
When the Data Selection key is pressed again the Multifunctional Data
Display will return to the preset voltage and wire feed speed.
If settings are unchanged for three seconds the Multifunctional Data
Display will flash once to indicate that the setting has been saved and
these will be retained, and displayed when the machine restarts.
45
Illustration 11. MIG mode – Fine adjustment of Inductance presetting range
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BOC Smootharc Multiprocess 175 Operating manual
11.0 Troubleshooting and Fault Finding
11.1 TIG/MMA functions
Excessive electrode consumption
Cause
Inadequate gas flow
Inadequate post gas flow
Improper size electrode for current required
Operating of reverse polarity
Electrode contamination
Excessive heating inside torch
Electrode oxidising during cooling
Shield gas incorrect
Solution
Increase gas flow
Increase post flow time to 1 sec per 10 amps
Use larger electrode
User larger electrode or change polarity
Remove contaminated portion, then prepare again
Replace collet. Try wedge collet or reverse collet
Increase post flow time before turning off valve
Change to proper gas (no oxygen or CO2)
Erratic Arc
Cause
Incorrect voltage (arc too long)
Current too low for electrode size
Electrode contaminated
Joint too narrow
Contaminated shield gas. Dark stains on the electrode or
weld bead indicate contamination
Base metal is oxidised, dirty or oily
Solution
Maintain short arc length
Use smaller electrode or increase current
Remove contaminated portion, then prepare again
Open joint groove
The most common cause is moisture or aspirated air in gas stream. Use welding grade gas only.
Find the source of the contamination and eliminate it promptly
Use appropriate chemical cleaners, wire brush, or abrasives prior to welding
Inclusion of tungsten or oxides in weld
Cause
Improper lift arc starting technique
Poor scratch starting technique
Excessive current for tungsten size used
Accidental contact of electrode with puddle
Accidental contact of electrode to filler rod
Using excessive electrode extension
Inadequate shielding or excessive drafts
Wrong gas
Heavy surface oxides not being removed
Solution
Follow directions as set out on page 43
Many codes do not allow scratch starts. Use copper strike plate. Use high frequency arc starter.
Reduce the current or use larger electrode
Maintain proper arc length
Maintain a distance between electrode and filler metal
Reduce the electrode extension to recommended limits
Increase gas flow, shield arc from wind, or use gas lens
Do not use ArO2 or ArCO2 GMAW (MIG) gases for TIG welding
Wire brush and clean the weld joint prior to welding
Porosity in Weld Deposit
Cause
Entrapped impurities, hydrogen, air, nitrogen, water vapour
Defective gas hose or loose connection
Filler material is damp (particularly aluminium)
Filler material is oily or dusty
Alloy impurities in the base metal such as sulphur,
phosphorous, lead and zinc
Excessive travel speed with rapid freezing of weld trapping
gases before they escape
Contaminated shield gas
Solution
Do not weld on wet material. Remove condensation from line with adequate gas pre-flow time
Check hoses and connections for leaks
Dry filler metal in oven prior to welding
Replace filler metal
Change to a different alloy composition which is weldable. These impurities can cause a
tendency to crack when hot
Lower the travel speed
Replace the shielding gas
BOC Smootharc Multiprocess 175 Operating manual
Cracking in Welds
Cause
Hot cracking in heavy sections or welding on metals prone
to hot cracking
Post weld cold cracking due to excessive joint restraint,
rapid cooling or hydrogen embrittlement
Centreline cracks in single pass weld
Underbead cracking from brittle microstructure
Solution
Increase weld bead cross-section size. Change weld bead contour for e.g. concave to flat or
convex, check fit-up gap, reduce welding speed
Preheat prior to welding. Use pure or non-contaminated gas. Increase the bead size. Prevent
craters or notches. Change the weld joint design
Increase bead size. Decrease root opening. Use preheat. Prevent craters
Eliminate sources of hydrogen, joint restraint, and use preheat
Inadequate shielding
Cause
Gas flow blockage or leak in hoses or torch
Excessive travel speed exposes molten weld to
atmospheric contamination
Wind or drafts
Excessive electrode stickout
Excessive turbulence in gas stream
Solution
Locate and eliminate the blockage or leak
Use slower travel speed or carefully increase the flow rate to a safe level below creating
excessive turbulence. Use a trailing shield cup
Set up screens around the weld area
Reduce electrode stickout. Use a larger size cup
Change to gas safer parts or gas lens parts
Short parts Life
Cause
Cup shattering or cracking in use
Short collet life
Short torch head life
Solution
Change cup size or type. Change tungsten position
Ordinary style is split and twists or jams. Change to wedge style
Do not operate beyond rated capacity. Do not bend rigid torches
The phenomenon listed below may happen due to relevant accessories used, welding material, surroundings and power supply.
Please improve surroundings and avoid these problems.
Phenomenon
Cause
Arc starting difficulty. Arc interruption happens easily
The output current fails to reach the set current
The current is unstable during operation:
This situation may relate to the following factors
Gas vent in welds
Solution
Examine whether grounding wire clamp contacts with the work pieces well.
Examine whether each joint has improper contact.
Check connects are tight and cables are not damaged. Ensure correct electrode size has been
selected.
The voltage of electric power network changes;
Serious interference from electric power network or other electric facilities.
Examine whether the gas supply circuit has leakage.
Examine whether there is sundries such as oil, dirt, rust, paint etc. on the surface.
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BOC Smootharc Multiprocess 175 Operating manual
11.2 MIG/MAG functions
Power source
Component
Primary cable
Earth cable and clamp
Connectors and lugs
Switches
Fault symptom
No or low welding output
Arc will not initiate
Overheating of connectors and lugs
Erratic or no output control
Cause
Poor or incorrect primary connection, lost phase
Damaged, loose or undersized cables and clamps
Loose or poorly crimped connectors
Switches damaged or incorrectly set for the application
Component
Gas solenoid valve
Wire feed rolls
Fault symptom
No gas flow or gas flows continuously
Wire slippage, wire deformation
Inlet, outlet guides
Torch connector
Wire shaving or snarling
Wire restriction, gas leaks, no trigger control
Wire feed speed control
No control over wire feed speed, no amperage
control
Wire live when feeding through cable and torch
before welding
Wire spool drags or overruns
Cause
Gas valve faulty or sticking in open position
Incorrect feed roll size, incorrect tension adjustment,
misalignment
Incorrect wire guide sizes, misalignment
Torch connector not correctly mounted or secured, incorrect size
of internal guide, bent contact pins
Faulty wire speed feed potentiometer, machine in overload or
trip condition
Faulty wire inch switch, activitation of torch trigger switch
Wire feeder
Wire inch switch
Spindle
Spindle brake set too tight or too loose, spool not properly
located on spindle
Welding torch
Component
Type
Liners
Fault symptom
Welding torch overheats
Erratic wire feed, wire snarls up at outlet guide
Gas distributor
Nozzle
Contact tip
Inadequate gas flow, contaminated or porous weld
Inadequate gas cover, restricted joint accessibility
Erratic feeding, wire shudder, wire burnback,
unstable arc, spatter
Arcing between contact tip and nozzle and
between nozzle and workpiece
Cause
Welding torch underrated for welding application
Liner of incorrect type and size for wire in use, worn or dirty
liner, liner too long or too short
Damaged or blocked distributor
Nozzle too large or too small, incorrect length or shape
Incorrect size of contact tip, incorrect contact tip to nozzle
distance for metal transfer mode, tip has worn out
No nozzle insulator fitted, spatter build up has caused parts to
short out
Fault symptom
No gas flow, gas leaks at regulator body or
cylinder valve
Leaks at connections or in the hose, porosity in
the weld
Cause
Blocked inlet stem, leaking inlet stem to body thread, bullnose
not properly seated in cylinder valve
Poorly fitted loose connections, damaged hose, air drawn into
gas stream
Fault symptom
Erratic wire feeding or wire stoppages
Wire sticks in contact tip, erratic feeding
Weld has excessive amount of spatter
Cause
Damaged wire basket, loose spooling, random-wound wire
Varying wire diameter, copper flaking, surface damage
Wrong polarity has been selected
Nozzle insulator
Regulator / flowmeter
Component
Inlet stem
Gas hose and fitting
Welding wire
Component
Wire basket and spool
Wire
Wire
BOC Smootharc Multiprocess 175 Operating manual
Porosity in Weld Deposit
Cause
Entrapped impurities, hydrogen, air, nitrogen, water vapour
Defective gas hose or loose connection
Filler material is damp (particularly aluminium)
Filler material is oily or dusty
Alloy impurities in the base metal such as sulphur,
phosphorous, lead and zinc
Excessive travel speed with rapid freezing of weld trapping
gases before they escape
Contaminated shield gas
Solution
Do not weld on wet material.
Check hoses and connections for leaks
Dry filler metal in oven prior to welding
Replace filler metal
Change to a different alloy composition which is weldable. These impurities can cause a
tendency to crack when hot
Lower travel speed
Replace the shielding gas
Inadequate shielding
Cause
Gas flow blockage or leak in hoses or torch
Excessive travel speed exposes molten weld to
atmospheric contamination
Wind or drafts
Excessive electrode stickout
Excessive turbulence in gas stream
Solution
Locate and eliminate the blockage or leak
Use slower travel speed or carefully increase the flow rate to a safe level without creating
excessive turbulence. Use a trailing shield cup
Set up screens around the weld area
Reduce electrode stickout. Use a larger size nozzle
Change to gas saver parts or gas lens, lower flow rate if possible
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BOC Smootharc Multiprocess 175 Operating manual
12.0 Periodic Maintenance
WARNING
Only authorised electricians should carry out repairs and internal
servicing.
Modification of the 15A primary input plug or fitment of a lower rated
primary input plug will render the warranty null and void.
The working environment or amount of use the machine receives should
be taken into consideration when planning maintenance frequency of
your Smootharc welder.
Preventative maintenance will ensure trouble-free welding and increase
the life of the machine and its consumables.
12.1 Power Source
• Check electrical connections of unit at least twice a year.
• Clean oxidised connections and tighten.
• Inner parts of machine should be cleaned
with a vacuum cleaner and soft brush.
• Do not use any pressure-washing devices.
• Do not use compressed air as pressure may pack dirt even more tightly
into components.
BOC Smootharc Multiprocess 175 Operating manual
13.0 Technical Specifications
Specifications
MULTIPROCESS 175
Part No.
Power voltage
Frequency
Rated input current
BOC175MULTI
Single phase 240 V ±15 %
50/60 Hz
28 A
Output current
MMA
TIG
MIG
Rated working voltage
No-load voltage
Duty cycle
Wire feeder
Wire feeder speed
Post flow time (S)
Welding wire diameter
Remote control
Efficiency
Power factor
Insulation grade
Housing protection grade
Welding thickness (mm)
Dimensions L × W × H
Weight
Standards
20 to 175 A
10 to 175 A
50 to 175 A
16.5 to 22.8 V
56 V
35 %
Internal
2 to 12 m/min
3
0.6/0.8/1.0 mm
No
80 %
0.73
F
IP23S
>0.8 mm
420 × 220 × 439 mm
12.8 kg
IEC 60974.1
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BOC Smootharc Multiprocess 175 Operating manual
14.0 Warranty Information
14.1 Terms of Warranty
14.3 Warranty Period
The Smootharc machine has a limited warranty that covers manufacturing
and material defects only. The warranty is affected on the day of
purchase and does not cover any freight, packaging and insurance costs.
Verbal promises that do not comply with terms of warranty are not
binding on warrantor.
The warranty is valid for 18 months from date of purchase provided the
machine is used within the published specification limits.
14.2 Limitations on Warranty
The following conditions are not covered under terms of warranty: loss or
damage due to or resulting from natural wear and tear, non‑compliance
with operating and maintenance instructions, connection to incorrect
or faulty voltage supply (including voltage surges outside equipment
specs), incorrect gas pressure overloading, transport or storage damage
or fire or damage due to natural causes (e.g. lightning or flood). This
warranty does not cover direct or indirect expenses, loss, damage of
costs including, but not limited to, daily allowances or accommodation
and travelling costs.
Modification of the 15A primary input plug or fitment of a lower rated
primary input plug will render the warranty null and void.
NOTE
Under the terms of warranty, welding torches and their consumables are
not covered. Direct or indirect damage due to a defective product is not
covered under the warranty. The warranty is void if changes are made
to the product without approval of the manufacturer, or if repairs are
carried out using non-approved spare parts. The warranty is void if a nonauthorised agent carries out repairs.
14.4 Warranty Repairs
A BOC approved service provider must be informed within the warranty
period of any warranty defect. The customer must provide proof of
purchase and serial number of the equipment when making a warranty
claim. Warranty repairs may only be carried out by approved BOC service
providers. Please contact your local BOC Gas & Gear for a directory of BOC
approved service providers in your area.
For more information contact the BOC Customer Service Centre.
BOC Australia
131 262
[email protected]
BOC Limited
10 Julius Avenue, North Ryde NSW 2113, Australia
www.boc.com.au
970–988 Great South Road, Penrose, Auckland, New Zealand
www.boc.co.nz
© BOC Limited 2013. BOC is a trading name of BOC Limited, a Member of The Linde Group. Reproduction without permission is strictly prohibited. Details given in this document are
believed to be correct at the time of printing. Whilst proper care has been taken in the preparation, no liability for injury or damage resulting from its improper use can be accepted.
MP11-0061 . FDAUS . 1213
BOC New Zealand
0800 111 333
[email protected]
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