Hobart Welding Products 125 manual Common Gmaw MIG Shielding Gases, Application, Fillet

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	Spray Arc	Short Circuiting	Spray Arc	Short Circuiting
		Steel	Stainless Steel	Stainless Steel	Aluminum	Aluminum
Argon					All Positions5	All Positions
Argon + 1% O2	Flat & Horizontal5		Flat & Horizontal5
	Fillet		Fillet
Argon + 2% O2	Flat & Horizontal5		Flat & Horizontal5
	Fillet		Fillet
Argon + 5% O2	Flat & Horizontal5
	Fillet
Argon + 8% CO2	Flat & Horizontal5	All Positions
	Fillet
Argon + 25%	Flat & Horizontal1	All Positions		All Positions3
CO2	Fillet
Argon + 50%		All Positions
CO2
CO2	Flat & Horizontal1	All Positions
	Fillet
Helium					All Positions2
Argon + Helium					All Positions2
Tri-Mix4				All Positions

1Globular Transfer

2Heavy Thicknesses

3Single Pass Welding Only

490% HE + 7-1/2% AR + 2-1/2% CO2

5Also for GMAW-P, All Positions

9-18. Troubleshooting Guide For Semiautomatic Welding Equipment

Problem	Probable Cause	Remedy
Wire feed motor operates, but	Too little pressure on wire feed rolls.	Increase pressure setting on wire feed rolls.
wire does not feed.
	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	Too much pressure on wire feed rolls.	Decrease pressure setting on wire feed rolls.
wire feed rolls (bird nesting).
	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.

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