LibGuides: Welding &amp; Joining Technology: Gas Metal Arc Welding (GMAW / MIG)

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MIG welding

GMAW

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MIG welding

GMAW

Gas Metal Arc Welding (GMAW)

Gas metal arc welding (GMAW) uses a solid electrode wire that is continuously fed from a spool, through the welding cable assembly, and out through the welding gun. Sometimes known as its subtypes of metal inert gas (MIG) welding or metal active gas (MAG) welding.

Diagram

The basic equipment for a typical GMAW semiautomatic setup includes a welding power source, wire feeders that ensure constant speed and voltage, a supply of electrode wire, a welding gun and a shielding gas cylinder.

Usage

Gas Metal Arc Welding is commonly used in the following areas:

Pipe welding/pipe joints
Automotive production and maintenance
Manufacturing
Shipbuilding
Construction
Railroad tracks
Underwater welding

Can be used to weld both ferrous and non-ferrous metals and all thicknesses above thin gauge sheet metal.

Metal transfer is through:

Short-circuit (GMAW-S): a solid metal-cored wire electrode is deposited during repeated electrical short circuits.
Globular Transfer: A continuously fed solid or metal-cored wire electrode is deposited in a combination of short-circuits and gravity-assisted large drops.
Axial Spray Transfer: high energy mode where a continuously fed solid or metal-cored wire electrode is deposited at a higher energy level, resulting in a stream of small molten droplets. The droplets are propelled axially across the arc.
Pulsed Spray Transfer (GMAW-P): Related to axial spray transfer, where the welding current is cycled between a high peak current level to a low background current level.