37 Lab Tips: GMAW Short Circuit

Settings

Acceptable ranges for welding GMAW short circuit:

• 16-22 volts
• 150 – 223 wire-speed

Example settings (notice how the numbers match?):

• 17 volts and 170 wire-speed
• 19 volts and 190 wire-speed
• 22 volts and 220 wire-speed

Use a gas mixture of 75% argon and 25% carbon dioxide for GMAW short circuit. For GMAW spray transfer, instead use a gas mixture of 90% argon and 10% carbon dioxide.

Other Tips

• Take mill scale off the joint (both the front and back sides).
• Prop the joint up off the table so it doesn’t stick.
• When welding verticle up, use lower settings with a slight triangle movement.

Common Mistakes

1. Not cleaning your material: get your material clean from mill scale and do not weld on rusted material.
2. Voltage issues: too high creates a globular weld, too low often doesn’t even melt the wire.
3. Wire feed speed issues: too high may not melt the wire, too low leads to single drops onto the plate rather than a continuous feed.
4. Electrical wire positioning: it is often recommended that the wire sticks out 3/4″ past the contact tip (not past the nozzle!) to the material.
5. Gas flow issues: too low creates porosity, too high wastes gas and may also create porosity.
6. Travel speed issues: too fast creates a too-narrow bead with peaks, too slow creates a super wide bead.
7. Gun angle: causes issues with shielding gas coverage if the push or drag angle is too much.