Mig Welding

What is mig welding?

Mig welding (Metal Inert Gas Welding) or Mag welding (Metal Active Gas Welding) is the most popular of all the arc welding processes, mainly because of its ease and versatility.

An arc is struck between a continuously fed Mig welding filler wire and the workpiece. The arc is protected from oxidisation by pouring a shielding gas over the weld pool. The type of gas depends on material and quality required.

  • Pure CO2 is the cheapest gas used in Mig welding. It delivers a harder weld and produces more spatter making it more suitable for jobs that don’t require a fine visual finish.
  • Argon / CO2 is the most versatile gas for Mig welding and is used for Mig welding steel and stainless steel. Argon / CO2 produces a less hard weld making it ideal for thinner material.
  • Pure Argon welding gas is only used for Mig welding aluminium. Welding aluminium is a complex process that requires an experienced Mig welding operator.

We use two methods of metal transfer from the welding filler wire to the workpiece:

Dip transfer

Dip transfer is achieved at lower voltage settings. The wire is fed into the weld pool creating a ‘short circuit’ creating heat which burns the wire off. This happens many times per second and is responsible for the characteristic crackling sound of Mig / Mag welding and the associated spatter. Dip transfer offers the advantage of being able to weld in position i.e. vertical.

Spray transfer

This is achieved at higher voltage settings. The filler wire is melted and transfers in globules to the weld pool. Spray transfer offers smoother welds with little welding spatter but cannot be used in position.

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