What is MIG Welding?

MIG (Metal Inert Gas) welding, also sometimes called GMAW (gas metal arc welding), is a welding process that was originally developed back in the 1940's for welding aluminum and other non-ferrous metals. MIG welding is an automatic or semi automatic process in which a wire connected to a source of direct current acts as an electrode joins two pieces of metal, as it is continuously passed through a welding gun. A flow of an inert gas (originally Argon) is also passed through the welding gun at the same time as the wire electrode. This inert gas acts as a shield, keeping air borne contaminants away from the weld zone.

The primary advantage of MIG welding is that it allows metal to be welded much quicker than traditional welding "stick welding" techniques. This makes it ideal for welding softer metals such as aluminum. When MIG welding was first developed, the cost of the inert gas (i.e., argon) made the process too expensive for welding steel. However, over the years, the MIG welding process has evolved and semi inert gases such as carbon dioxide can now be used to provide the shielding function which makes MIG welding cost effective for welding steel.

MIG Welding

Gas Metal Arc Welding (GMAW) is frequently referred to as MIG welding. MIG welding is a commonly used high deposition rate welding process. Wire is continuously fed from a spool. MIG welding is therefore referred to as a semiautomatic welding process.

MIG Welding Benefits

* All position capability
* Higher deposition rates than SMAW
* Less operator skill required
* Long welds can be made without starts and stops
* Minimal post weld cleaning is required

MIG Welding Shielding Gas

The shielding gas, forms the arc plasma, stabilizes the arc on the metal being welded, shields the arc and molten weld pool, and allows smooth transfer of metal from the weld wire to the molten weld pool. There are three primary metal transfer modes:

* Spray transfer (MP3 Audio)
* Globular transfer (MP3 Audio)
* Short circuiting transfer (MP3 Audio)

The primary shielding gasses used are:

* Argon
* Argon - 1 to 5% Oxygen
* Argon - 3 to 25% CO2
* Argon/Helium

CO2 is also used in its pure form in some MIG welding processes. However, in some applications the presence of CO2 in the shielding gas may adversely affect the mechanical properties of the weld.

Common MIG Welding Concerns

We can help optimize your MIG welding process variables. Evaluate your current welding parameters and techniques. Help eliminate common welding problems and discontinuities such as those listed below:

Weld Discontinuities

* Undercutting
* Excessive melt-through
* Incomplete fusion
* Incomplete joint penetration
* Porosity
* Weld metal cracks
* Heat affected zone cracks


MIG Welding Problems

* Heavily oxidized weld deposit
* Irregular wire feed
* Burnback
* Porosity
* Unstable arc
* Difficult arc starting

If your company is experiencing these or other welding problems you can retain AMC to improve your weld processing. Hire AMC to act as your welding specialist.