MIG WeldingThe patent for what we now know as the MIG process was granted on the 21st January 1949 to Muller, Gibson and Anderson of the Air Reduction Company (AIRCO), now BOC Gases America, for their invention of a process they termed SIGMA (Shielded Inert Gas Metal Arc) welding. The term most commonly used to describe this process is MIG (Metal Inert Gas) welding, even though the shielding gas used may not be totally inert. In some countries a differentiation to the naming convention is made based on the shielding gas used. In Europe for example, MIG is used only when a totally inert gas shield e.g. Argon is used, and the MAG (Metal Active Gas) being preferred when the shielding gas also contains active constituents, such as carbon dioxide or oxygen. A shielding gas of 100%CO2 may also be referred to as 'MAG', although some customers may refer to the process as 'CO2 welding' or 'semi-automatic welding'. In the USA, the term GMAW (Gas Metal Arc Welding) is often used, and covers use of both inert and active shielding gases. Originally, the process was designed for welding aluminium and its alloys, using pure argon or helium shielding gas, but has been developed into what we know today as a process capable of welding a wide range of ferrous and non-ferrous metals and alloys.
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