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Guidelines To
Gas Metal Arc Welding
(GMAW)
WARNING
ARC WELDING can be hazardous.
This document contains general information about the topics discussed herein. This document is
not an application manual and does not contain a complete statement of all factors pertaining to
those topics.
This installation, operation, and maintenance of arc welding equipment and the employment of
procedures described in this document should be conducted only by qualified persons in
accordance with applicable codes, safe practices, and manufacturer’s instructions.
Always be certain that work areas are clean and safe and that proper ventilation is used. Misuse
of equipment, and failure to observe applicable codes and safe practices, can result in serious
personal injury and property damage.
PRINTED IN USA
WARNING
ELECTRIC SHOCK can kill.
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Always wear dry insulating gloves.
Insulate yourself from work and ground.
Do not touch live electrical parts.
Keep all panels and covers securely in place.
FUMES AND GASES can be hazardous to your health.
Keep your head out of the fumes.
Ventilate area, or use breathing device.
Read Material Safety Data Sheets (MSDSs) and manufacturer’s instructions
for material used.
WELDING can cause fire or explosion.
Do not weld near flammable material.
Watch for fire; keep extinguisher nearby.
Do not locate unit over combustible surfaces.
Do not weld on closed containers.
Allow work and equipment to cool before handling.
ARC RAYS can burn eyes and skin; NOISE can damage
hearing.
Wear welding helmet with correct shade of filter.
Wear correct eye, ear, and body protection.
MOVING PARTS can cause injury.
Keep away from pinch points such as drive rolls.
Keep all doors, panels, covers, and guards closed and securely in place.
HOT PARTS can cause injury.
Allow cooling period before touching welded metal.
Wear protective gloves and clothing.
MAGNETIC FIELDS FROM HIGH CURRENTS can affect
pacemaker operation.
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Pacemaker wearers keep away.
Wearers should consult their doctor before going near arc welding, gouging, or
spot welding operations.
WELDING CURRENT can damage electronic parts in
vehicles.
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Disconnect both battery cables before welding on a vehicle.
Place work clamp as close to the weld as possible.
See Safety Precautions at beginning of welding power source Owner’s Manual
for basic welding safety information.
swarn6.2* 8/92
154 557 Page 1
1. Gas Metal Arc Welding (GMAW)
Regulator/
Flowmeter
115V/24V
Wire
Feeder
Gun
Gas
Contactor
Shielding
Gas
Welding
Power
Source
Work
Electrode Lead
Work Lead
ST-800 357-A
Figure 1. Typical GMAW Process Connections
154 557 Page 2
NOTE
These settings are guidelines only. Material and wire type, joint
design, fitup, position, shielding gas, etc. affect settings. Test welds
to be sure they comply to specifications.
Material thickness determines
weld parameters.
1/8 or
.125 in
Convert Material
Thickness To
Amperage (A)
(.001 in = 1 ampere)
.125 in = 125 A
.035 in
Wire Size
.030 in
.035 in
.045 in
Amperage Range
40 – 145 A
50 – 180 A
75 – 250 A
Select Wire Size
Wire
Size
.030 in
.035 in
.045 in
Recommendation
Wire Speed
(Approx.)
Select Wire Speed
(Amperage)
125 A based on 1/8 in
material thickness
ipm = inch per minute
2 in per ampere
2 x 125 A = 250 ipm
1.6 in per ampere 1.6 x 125 A = 200 ipm
1 in per ampere
1 x 125 A = 125 ipm
Low voltage: wire stubs into work
High voltage: arc is unstable (spatter)
Set voltage midway between high/low voltage.
Select Voltage
Wire speed (amperage) con-
trols weld penetration. (wire
speed = burn-off rate)
Voltage controls height
and width of weld bead.
ST-800 354
Figure 2. Typical GMAW Process Control Settings
154 557 Page 3
NOTE
Welding wire is energized when gun trigger is pressed. Before
lowering helmet and pressing trigger, be sure wire is no more than
1/2 in (13 mm) past end of nozzle, and tip of wire is positioned
correctly on seam.
1
2
3
4
5
Hold Gun And Control Gun
Trigger
Workpiece
Work Clamp
Electrode Extension (Stickout)
1/4 To 1/2 in (6 To 13 mm)
Cradle Gun And Rest Hand
On Workpiece
1
2
3
5
4
0
°
-15
°
90
°
90
°
End View Of Work Angle
Side View Of Gun Angle
GROOVE WELDS
45
°
45
°
0
°
-15
°
End View Of Work Angle
Side View Of Gun Angle
S-0421-A
FILLET WELDS
Figure 3. Holding And Positioning Welding Gun
154 557 Page 4

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