1. Gas Metal Arc Welding
GMAW

2. 5 Essentials of Arc Welding
Arc Length
Travel Speed
Electrode Angle
Electrode
Machine Setting

3. GMAW Machine Settings Machine setting depends on thickness of metal.
Voltage (see chart on machine)
Wire speed (see chart on machine)
Shielding gas (100% Carbon Dioxide = 25cfh)
Protects weld area from contamination.
Non-Inert = CO2
Inert = Argon
Gas Drift: Windy conditions move the shielding gas away from the weld area resulting in a poor weld.

4. Electrode (wire) Type of wire depends on base metal.
Mild steel base metal = mild steel wire.
Various sizes (.023”, .030”, .035”, .045”)
All machines in our shop are set up with .030” mild steel wire.

5. Electrode Angle Work angle (front to back)
Flat welds = 90
T – Joint = 45
Travel angle (right to left)
Always 90

6. Travel Speed
Resulting weld should be 3/16” – ¼” wide.

7. Arc Length
Stickout: Length of wire sticking out from the welding tip. Should be around ¼”.
Listen carefully to your weld, should have a constant sizzle, no cracking or popping.

8. Welding Gun
When you pull the trigger on the welding gun 3 things happen simultaneously:
Shielding gas starts
Wire-feed starts
Arc starts
Parts:
Nozzle: Directs shielding gas to weld area/
Tip: Directs the wire to weld area.
Distributor: Disperses shielding gas.
Trigger: Starts and stops welding operation.

9. GMAW Related Terms
Cold lap: Non-penetrating weld; weld sits on top of or overlaps base metal.
Causes: Improper machine setting, low heat, improper arc length(stickout).

10. GMAW Safety Equipment/Tools
Welding helmet
Safety glasses
Gloves
Long sleeves
Hair tied back
Needle-nose pliers
Wire-brush