Gas Metal Arc Welding: Working Principle, Advantages and Applications

What is Gas Metal Arc Welding?

Gas metal arc welding (GMAW) 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. The gas metal arc welding is also known as metal inert gas (MIG) welding or metal active gas (MAG) welding. MIG and MAG are the subtypes of the gas metal arc welding.

Gas metal arc welding was originally developed for welding aluminum and other non-ferrous materials in the 1940s. Although, the gas metal arc welding was soon applied to steels as it allowed for smaller welding time than the other welding methods.

In case of GMAW, a constant voltage DC power supply is most commonly used, however a constant current AC power supply can also be used. The primary methods of metal transfer in the gas metal arc welding process are as −

• Globular Method

• Short-Circuiting Method

• Spray Method

• Pulsed Spray Method

Each of these four methods of metal transfer in GMAW has distinct properties and corresponding advantages and limitations.

Working Principle of Gas Metal Arc Welding

A simple schematic diagram of the gas metal arc welding process is shown in the figure below.

In gas metal arc welding, the heat is produced by an electric arc incorporating a continuous feed consumable electrode that is shielded by an externally supplied gas. The process of GMAW requires a welding gun, a source of electric power supply, an electrode wire feed unit, and a source of shielding gas. The welding gun guides the electrode wire, current wire and shielding gas tube. In GMAW, the self-regulation of the arc length is maintained by a constant voltage power supply with a constant wire feed speed unit.

Today, the gas metal arc welding is the most common industrial welding process, preferred for its versatility, speed and automation.

Advantages of Gas Metal Arc Welding

The chief advantages of gas metal arc welding are given as follows −

• Gas metal arc welding process requires no flux.

• GMAW can be adapted for manual and automatic operations.

• It requires no cleaning after the welding is done.

• Gas metal arc welding requires much less skilled welder for it operation.

• GMAW is suitable for horizontal, vertical and overhead welding positions.

• It provides complete protection to weld from atmospheric contamination.

• Gas metal arc welding can be used for both ferrous and non-ferrous metals.

Applications of Gas Metal Arc Welding

Some of the applications of the gas metal arc welding are given as follows −

• It is used in the semi-automated or automated industrial applications.

• Gas metal arc welding can be used to weld the all commercially available metals.

• GMAW can be used for deep groove welding of plates and castings.

• GMAW is also used for welding of light gauge metals, where high speeds are possible.