Gas Metal Arc Welding, also known as MIG welding (Metal Inert Gas) or wire welding, is a welding procedure using a consumable electrode fed by machine and a shielding gas, usually inert. Much like GTAW, the electrode is mounted coaxially in the center of the gas nozzle, which provides protection from atmospheric contaminants without the need for flux. However, like SMAW, the filler material is the consumable electrode.

GMAW is called wire welding, as the filler/electrode material comes as spools of wire. The wire is fed through a set of drive rollers which push the wire through the electric contact in the center of the gas nozzle. The wire creates the arc with the workpicece which forms the weld pool and since it's also the filler material, the weld bead is formed at the same time.

GMAW's benefits are quite numerous

  • High rate of filler metal deposition
  • Narrow weld bead
  • Minimum distortion of workpiece
  • Very easy to learn
  • Clean, precise welds

The main disadvantages

  • Expensive and complex equipment
  • Setting up equipment can be time consuming and tricky

GMAW revolutionized many manufacturing processes, as welds could now be done much faster and with much better consistency. GMAW is currently used is nearly all assembly line processes, such as welding vehicle frames, pipe welding and structural welding, just to mention a few.

The shielding gas used may be inert, usually Argon or Helium, or active, such as Carbon Dioxide, Oxygen or a mix of some of these gases. GMAW using active gases is also known as MAG welding (Metal Active Gas).

GMAW is a DC welding process, and can be used with straight or reverse polarity. A pulsing controller can also be used for some applications in lieu of using AC.

After the wire feeder and weld machine are set up properly, running a bead of weld is as simple as it can get. Place the nozzle near the surface to be welded, flip down the weld hood, pull the trigger and put the filler metal where the weld is needed.

Disclaimer:don't do this unless you know what you're doing or have proper supervision. wear proper safety gear. if you get hurt, it's your own damn fault. remember, you're melting metal with electricity here. IT MIGHT GET HOT AND SPARKY. YOU MIGHT GET BURNED OR SHOCKED.

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