Whilst not an overly popular method when it comes to welding aluminium, the metal inert gas (MIG) welder, also known as a gas metal arc welder (GMAW) is still a useful skill to learn. But how does this process work?
The MIG welder generates the heat that it needs to weld metal together through an electric arc. This arc is created between the wire being fed through the welder and the aluminium metal itself. An inert gas is used to create shield (or a protective atmosphere) around the arc, preventing the metal from turning an ugly brown colour. When it comes to welding aluminium, argon is the most recommended gas to use, however, a mix of argon and helium may also work.
Before you begin MIG welding your aluminium project, the most important thing to ensure is that you have properly cleaned the metal. When it comes into contact with oxygen, the top layer of aluminium will oxidize and you will need to remove this to prevent the metal from cracking. The best way to clean aluminium is to run a stainless steel brush over the surface.
Aluminium has a low melting point and high heat conductivity, which leads to difficulties when it comes to welding. There is a fine line between having no penetration, meaning that the metal will not join, and blowing holes in the surface of your aluminium. It will take some practice to get the balance just right, so never start on your project straight away.
Welding aluminium using a MIG welder can be much harder (and less neat) then using a TIG welder, so it is always a good idea to take a class or to practice on some scrap aluminium first.