Gas metal arc welding (GMAW) is an automatic or semi-automatic welding process. Shielding gas and a continuous, consumable wire electrode are fed through a welding gun. GMAW uses a constant power source such as voltage or a direct current to weld together materials such as steel and aluminum. GMAW is popular in industries such as car manufacturing due to its speed and versatility.
GMAW is widely used by the sheet metal industry. Arc spot welding has replaced resistance or rivet welding. It is also used in robot welding, in which robots operate the welding gun and the sheet metal in order to save on time and cost. GMAW is not generally suitable for outdoor use, as changes in the atmosphere can cause the shielding gas to dissipate and the quality of the weld to be inferior. It is also unsuitable for underwater welding for the same reasons.
The equipment used in GMAW is a welding gun, a wire feed unit, an electrode wire and a shielding gas supply. When the control switch is turned on the wire feed, electrical power and gas flow are initiated. This causes an electric arc to be struck. The gas nozzle is used to direct the welding gas evenly into the welding zone.
GMAW can be extremely dangerous if the proper precautions are not taken. Welders must wear protective clothing, including long sleeved jackets capable of withstanding heat and flames. Leather gloves should also be worn when handling the welding gun. The brightness of the electric arc can also cause the retina in the eye to burn, so helmets with protective faceplates must be used to prevent exposure. GMAW should never be attempted without the implementation of all proper safety procedures.
Gas metal arc welding uses an arc between a constant filler metal (consumable) electrode and the weld pool. Shielding is provided by an externally supplied shielding gas. This method is also known as MIG welding or MAG welding. MIG (Metal Inert Gas) welding is defined as the use of an inert (i.e. non active) gas. MAG (Metal Active Gas) welding involves the use of an active gas (i.e. carbon dioxide and oxygen). CO 2 is a more frequently used shortening of MAG welding gas.
Gas metal arc welding consists of a DC arc burning between a thin bare metal wire electrode and the workpiece. The arc and weld area are encased in a protective gas shield. The wire electrode is fed from a spool, through a welding torch which is connected to the positive terminal into the weld zone. Gas metal arc welding is the most widely used process in the world today. GMAW is a versatile method which offers a lot of advantages. The technique is easy to use and there is no need for slag-cleaning. Another advantage is the extremely high productivity that Gas Metal Arc Welding makes possible.
Gas metal arc welding is used on all thicknesses of steels, aluminum, nickel, stainless steels etc. The MAG process of GMAW is suitable both for steel and unalloyed, low-alloy and high-alloy based materials. The MIG process of GMAW, on the other hand, is used for welding aluminum and copper materials.
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