What is MIG/MAG welding?

MAG Welding with solid wire
Gas Metal Arc welding or welding with shielding gas, as it is often called, is a welding arc process which utilizes the heat of an electric arc established between a continuoually feeded wire and the workpiece. During this process the wire will melt and the weld metal is transferred to the workpiece.

The weld pool is always protected by a shield of gas in order to protect both the melting wire and the weld pool from the oxygen and nitrogen in the air. If these gases enter into the shielding gas atmosphere, it may cause porosities in the weld. Exterior disturbances such as draugths from open doors and windows may cause the shielding gas to blow away.

Also ventilating air currents may influence on the welding place and the shielding gas. The shielding gas is usually divided into two submethods according to the applied type of shielding gas.

MIG welding
MIG welding is welding in an atmosphere of inert gas, which means welding with a shielding gas that does not react with other substances. Inert gases are for instance argon and helium of which argon is more used within the European region. Usually, the process is called MIG welding even when the inert gas is mixed with small quantities of O2, CO2, H2 or similar substances.

MAG welding
MAG welding is welding in an atmosphere of reacting gases, or as it is also called: shielded by an active gas. This means that the gas is separated in the arc and to a smaller or larger extent reacts with the weld pool. CO2 is mainly used as shielding gas which is why the process is also known as CO2 welding.

Advantages of MIG/MAG welding:

  • The method is financially attractive due to a high welding speed and because a long arc time can be maintained as there is no frequent changing of electrode rods.
  • The method provides the opportunity for rational welding of materials that are difficult to weld.
  • Welding is possible in all positions.
  • The arc and the weld pool is clearly visible.
  • Usually only little aftertreatment of the weld is necessary. 
  • Applications

MIG/MAG welding is usually used with:

  • Aluminium
  • Ordinary mild steels
  • Stainless steels
  • Copper and copper alloys

In addition to the above metals this method is suited for magnesium, nickel and a number of other metals and metal alloys.

MAG Welding with flux cored wire
For many years, the industry has wanted a semi-automatic arc welding process with continuously fed wire without exterior coating and with a higher deposition rate than that of solid wire, known from the MAG welding process.

If in addition, a higher safety against welding errors could be obtained, so such a semi-automatic process could be used for welding in thicker dimensions, where traditionally coated electrodes were used, it would be even better.

By means of the wire flux, it is possible to influence the physical conditions in the arc and the transfer of material, and also influence the metallurgic conditions. In this way some of the disadvantages and limitations of MAG welding with solid wire have been set up. Flux cored wires for AC welding can be produced in the same way as coated electrodes.

Advantages of MIG/MAG welding with flux cored wire:

  • The method is economical due to the high welding speed and because it is possible to maintain the arc in a long time as there is no need to change the electrode.
  • The method offers the possibility to weld difficult weldable materials in a rational way.
  • Welding can be done in all position. The arc and the weld pool are completely visible. Usually there is only little after-treatment.
  • The risk of serious welding errors is reduced compared to welding with solid wire.
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