30
Wire types and sizes - Use the correct wire type for the base metal being welded. Use stainless
steel wire for stainless steel, aluminium wires for aluminium and steel wires for steel.
Use a smaller diameter wire for thin base metals. For thicker materials use a larger wire diameter
and larger machine, check the recommended welding capability of you machine.
As a guide refer to the “Welding Wire Thickness Chart” below.
Gas selection - The purpose of the gas in the MIG process is to protect / shield the wire, the arc
and the molten weld metal from the atmosphere. Most metals when heated to a molten state will
react with the air in the atmosphere, without the protection of the shielding gas the weld produced
would contain defects like porosity, lack of fusion and slag inclusions. Additionally some of the gas
becomes ionised (electrically charged) and helps the current flow smoothly.
The correct gas flow is also very important in protecting the welding zone from the atmosphere.
Too low flow will give inadequate coverage and result in weld defects and unstable arc conditions.
Too high flow can cause air to be drawn into the gas column and contaminate the weld zone.
Use the correct shielding gas. Co2 is good for steel and offers good penetration characteristics,
the weld profile is narrower and slightly more raised than the weld profile obtained from Argon Co2
mixed gas. Argon Co2 mix gas offers better weld ability for thin metals and has a wider range of
setting tolerance on the machine. Argon 75% Co2 25% is a good all round mix suitable for most
applications.
Argon Co2
Co2
Penetration Pattern for Steel
WELDING WIRE DIAMETER CHART
RECOMMENDED WIRE DIAMETERS
MATERIAL
THICKNESS
24 Gauge (.60mm)
22 Gauge (.75mm)
20 Gauge (.90mm)
18 Gauge (1.0mm)
16 Gauge (1.2mm)
14 Gauge (1.9mm)
0.118” / 3.0mm
0.196” / 5.0mm
0.236” / 6.0mm
0.314” / 8.0mm
0.393” / 10.mm
0.472” / 12.0mm
0.025”
0.030”
0.035”
0.040”
MIG SOLID WIRE
GASLESS FLUX CORED WIRE
0.030”
0.035”
0.045”
For material thickness of 0.196” / 5.0mm and greater, multi-pass runs or a beveled
joint design may be required depending on the amperage capability of your machine.
