Gas metal arc welding (GMAW), commonly called metal inert gas welding (MIG
welding), is a type of welding which utilizes a welding gun through which a
continuous wire electrode and an inert shielding
is fed. The wires used in the electrodes are typically 0.7, 1.0, 1.2 or 1.6 mm
diameter, and usually solid. A related wire-welding process called flux-cored
arc welding (FCAW) uses a hollow wire filled with a flux, eliminating the need
for a shielding gas. Typically a constant voltage welding power supply is used
for GMAW but it is possible to use a voltage sensing wire feeder with a constant
current power source.
When welding steel, to prevent nitrogen and oxygen contaminating the weld,
an inert shielding gas is fed around the arc, usually 75% argon and 25% carbon
dioxide. The gas is fed in sufficient quantity to completely blanket the arc and
the liquid metal near it. When welding aluminum the same principle is used;
however, the gas is pure argon.
In metal active gas (MAG) welding, a mixture of gases is used that reacts
with the metal to improve the weld quality. Usually a varying mixture of argon
and carbon dioxide and traces of hydrogen.
MIG/MAG welding is typically used in the automobile industry as relatively
thin sheet metal can be welded. It is best used in flat welds as it is
difficult, but not impossible, to perform vertical and overhead welding using
Using MAG welding it is possible to weld aluminum, copper and stainless