Hobart Welding Products 140 manual Common MIG Shielding Gases, Application

9-16. Common 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	Short Circuiting	Aluminum
			Stainless Steel
Argon				X
Argon + 25% CO2		X
80% or greater Argon +	X	X1
balance CO2 or Oxygen
100% CO2		X
Tri-Mix2			X

1Limited short circuiting use

290% HE + 7-1/2% AR + 2-1/2% CO2

9-17. 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.
Wire feeds, but no gas flows.	Gas cylinder empty.	Replace empty gas cylinder.
	Gas nozzle plugged.	Clean or replace gas nozzle.
	Gas cylinder valve not open or flowmeter not adjusted.	Open gas valve at cylinder and adjust flow rate.
	Restriction in gas line.	Check gas hose between flowmeter and wire feeder, and
		gas hose in gun and cable assembly.
	Loose or broken wires to gas solenoid.	Have Factory Authorized Service Agent repair wiring.
	Gas solenoid valve not operating.	Have Factory Authorized Service Agent replace gas
		solenoid valve.
	Incorrect primary voltage connected to welding power	Check primary voltage and relink welding power source
	source.	for correct voltage.

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