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OM-947 Page 38
9-17. Common GMAW (MIG) Shielding Gases
This is a general chart for common gases and where they are used. Many different combinations (mixtures) of
shielding gases have been developed over the years. The most commonly used shielding gases are listed in the
following table.
Application
Gas
Spray Arc Steel
Short Circuiting
Steel
Spray Arc
Stainless Steel
Short Circuiting
Stainless Steel
Spray Arc
Aluminum
Short Circuiting
Aluminum
Argon All Positions
5
All Positions
Argon + 1% O
2
Flat & Horizontal
5
Fillet
Flat & Horizontal
5
Fillet
Argon + 2% O
2
Flat & Horizontal
5
Fillet
Flat & Horizontal
5
Fillet
Argon + 5% O
2
Flat & Horizontal
5
Fillet
Argon + 8% CO
2
Flat & Horizontal
5
Fillet
All Positions
Argon + 25%
CO
2
Flat & Horizontal
1
Fillet
All Positions All Positions
3
Argon + 50%
CO
2
All Positions
CO
2
Flat & Horizontal
1
Fillet
All Positions
Helium All Positions
2
Argon + Helium All Positions
2
Tri-Mix
4
All Positions
1 Globular Transfer
2 Heavy Thicknesses
3 Single Pass Welding Only
4 90% HE + 7-1/2% AR + 2-1/2% CO
2
5 Also for GMAW-P, All Positions
9-18. Troubleshooting Guide For Semiautomatic Welding Equipment
Problem Probable Cause Remedy
Wire feed motor operates, but
wire does not feed.
Too little pressure on wire feed rolls. Increase pressure setting on wire feed rolls.
Incorrect wire feed rolls. Check size stamped on wire feed rolls, replace to match
wire size and type if necessary.
Wire spool brake pressure too high. Decrease brake pressure on wire spool.
Restriction in the gun and/or assembly. Check and replace cable, gun, and contact tip if
damaged. Check size of contact tip and cable liner,
replace if necessary.
Wire curling up in front of the
wire feed rolls (bird nesting).
Too much pressure on wire feed rolls. Decrease pressure setting on wire feed rolls.
Incorrect cable liner or gun contact tip size. Check size of contact tip and check cable liner length
and diameter, replace if necessary.
Gun end not inserted into drive housing properly. Loosen gun securing bolt in drive housing and push gun
end into housing just enough so it does not touch wire
feed rolls.
Dirty or damaged (kinked) liner. Replace liner.