Longevity ARCMATE 205 - Manual (Page 25)

160/205 MIG Welder/ARC Welder
Page 24 of 37
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MIG Welding Process
Gas metal arc welding (GMAW), sometimes referred to by its subtypes metal inert gas (MIG)
welding or metal active gas (MAG) welding, is a semi-automatic or automatic arc welding
process in which a continuous and consumable wire electrode and a shielding gas are fed through
a welding gun. 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.
Originally developed for welding aluminum and other non-ferrous materials in the 1940s,
GMAW was soon applied to steels because it allowed for lower 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. The automobile industry in particular uses GMAW welding almost exclusively.
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 air volatility. A related process, flux cored arc
welding, often does not utilize a shielding gas, instead employing a hollow electrode wire that is
filled with flux on the inside.