An Introduction to Gas Metal Arc Welding (GMAW)

Oil & Gas, Petrochemical, Refining, Sugar
Mar | 1 | 2017

Gas Metal Arc Welding (GMAW) is commonly used for welding alloys, such as stainless steel and aluminum, or any work involving brazing, fabrication or pipework.

How GMAW Works
The electrode in GMAW consists of a roll of wire that is fed into the work piece by a ‘gun’. The rolled wire electrode allows for the creation of long continuous welds without the need for regular replacements. The gun also produces a cloud of inert gas (e.g., Argon) in order to displace oxygen near the welding area.

GMAW is generally considered one of the fastest methods of welding. Shielding gas delivery and wire feed can be automated to further accelerate the process. The minimal slag and spatter produced also reduces time and labor costs on post-weld clean up. Another advantage of GMAW is that it produces far less metal waste and no electrode stubs to dispose of. Overall, it is generally considered to be one of the cleanest methods of welding and does not necessarily require a highly trained operator to perform.

GMAW requires shielding gas and can only be used indoors, sheltered from winds that may displace the gas but not so sheltered that the gas is too confined. The high temperatures and limited slag mean vertical and overhead welding is impossible with GMAW. It is also considered a costlier welding technique due to maintenance of electronic equipment.

GMAW Pulse
To solve some the problems associated with the basic GMAW method, GMAW Pulse (GMAW-P) was created. GMAW-P rapidly oscillates electrical current, from high to low up to 400 times per second, creating molten metal without needing extreme temperatures. Lower temperatures mean a smaller weld pool, which allows for vertical or overhead welding, as well as welding of thinner materials. GMAW-P is generally more costly and less portable than standard GMAW.


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