<P> Gas metal arc welding (GMAW), sometimes referred to by its subtypes metal inert gas (MIG) welding or metal active gas (MAG) welding, is a welding process in which an electric arc forms between a consumable wire electrode and the workpiece metal (s), which heats the workpiece metal (s), causing them to melt and join . </P> <P> Along with the wire electrode, a shielding gas feeds through the welding gun, which shields the process from contaminants in the air . The process can be semi-automatic or automatic . A constant voltage, direct current power source is most commonly used with GMAW, but constant current systems, as well as alternating current, can be used . There are four primary methods of metal transfer in GMAW, called globular, short - circuiting, spray, and pulsed - spray, each of which has distinct properties and corresponding advantages and limitations . </P> <P> Originally developed for welding aluminium and other non-ferrous materials in the 1940s, GMAW was soon applied to steels because it provided faster welding time compared to other welding processes . The cost of inert gas limited its use in steels until several years later, when the use of semi-inert gases such as carbon dioxide became common . Further developments during the 1950s and 1960s gave the process more versatility and as a result, it became a highly used industrial process . Today, GMAW is the most common industrial welding process, preferred for its versatility, speed and the relative ease of adapting the process to robotic automation . Unlike welding processes that do not employ a shielding gas, such as shielded metal arc welding, it is rarely used outdoors or in other areas of moving air . A related process, flux cored arc welding, often does not use a shielding gas, but instead employs an electrode wire that is hollow and filled with flux . </P>

Describe the spot welding process using a gmaw welder
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