Gas Metal Arc Welding:

In the year 1948, the second important gas shielded arc welding procedure made its appearance and was to prove capable of being utilized satisfactorily on many of the types of joint which were not ideally suitable to the tungsten-arc method. In tungsten-arc welding the electrode was non-consumable, however in the new method the electrode was in the form of wire that was consumed throughout welding to provide filler metal for the weld. This wire was fed from a coil to the arc at the similar rate as it was melted away. The term metal-arc is utilized to describe an arc-welding procedure in which the electrode is consumed throughout welding to provide filler metal for the weld. GMAW covers inert along with active shielding gases. The term MIG (Metal Inert Gas) welding was utilized for the GMAW while the argon shielding is utilized as Argon is an inert gas. But in Metal Arc welding procedure shielding gases can be active gases as well like carbon dioxide, argon-oxygen and argon-CO₂ mixture, which are chemically active gases.

GMAW is fundamentally a semi-automatic process, in which the arc length & the feeding of the wire into the arc are automatically controlled. Thus operator's job is mainly to location the gun at a right angle and moving it at a controlled travel speed.

Basic equipment utilized consists of DC-power source, a shielding gas supply, a wire feeder,  controls for governing wire drive, gas flow and cooling water and a welding gun.

In this procedure the electrode tip to the weld pool across the arc is either globular, spray type or short-circuiting type based on the magnitude of welding current, current density, shielding gas and type of electrode.