MIG Welding

MIG – Metal Inert Gas, also referred to as GMAW. GMAW – Gas Metal arc welding

MIG Welding A semi-automatic welding process using a DC power source, a wire feeder, shielding inert gas, and a consumable electrode.

Advantages of MIG Faster than arc Smooth bead Easy to start b/c can place nozzle on metal without creating arc No slag to chip off Less damage to base metal b/c of fast travel speed Can join both ferrous and nonferrous metals (can be used with aluminum and stainless) No electrode stub loss

Disadvantages of MIG Machine cost more than stick welder Difficult to use in hard to get places

MIG Gas pressure of 20 psi Gas mixture: 75% argon 25% CO2

Purpose of Gas Mixture Keeps nitrogen and oxygen out of weld bead Increases penetration Reduces spatter

MIG Wire size: inches Mild steel copper coated electrode Welding Jelly can be used to prevent spatter from sticking to tip Use at least a number 10 shade lenses, 12 is sometimes recommended. Almost all MIG welding is performed in the direct current electrode positive mode (DCEP)

3 adjustments must be in balance to achieve a quality weld Voltage control volts Wire feed speed Shielding gas flow rate psi