Aluminum welding is actually less energy intensive and therefore easier than welding steel; however, there can be some difficulty in using equipment that is calibrated for use on steel with aluminum, so be sure to consult the documentation for your welding apparatus before attempting to weld aluminum. Several primary methods are used for the joining of aluminum via welding: mig welding, tig welding and using a stick electrode.
Mig Welding Aluminum
Mig welding, or gas metal arc welding as it is formally known, is a process that will require some post-weld touchups for a presentable finish. Mig welding uses an electrode of continually fed wire forming the base of the welds, which is also shielded by an inert gas or gas mixture. In terms of its use of aluminum, mig welding is considered somewhat messy because you'll need to use the spray transfer method in which the arc creates a spray of tiny metal beads. With practice the spray method becomes more controllable.
Tig Welding Aluminum
Tig welding, or gas tungsten arc welding as it is properly called, is a process that doesn't require much post-weld clean up and finishing, and is therefore ideally suited to quick and easy weldings of aluminum. Rather than using a fed-wire electrode, tig welding uses a permanent tungsten electrode that is not consumed by the welding process. You will need to add any filler metal manually, making this process best suited to joints that can be achieved without additional metal. As with mig welding, an inert gas is used to shield the arc.
Welding Aluminum with a Stick Electrode
Stick electrode welding is known by the technical name of shielded metal arc welding and is a process commonly referred to as the least expensive method of aluminum welding, whereby the shielding is provided by the coating around the electrode itself. Stick electrode welding does create some slate and requires considerable cleanup at the end of the job. The term stick welding is used because the electrode rod or “stick” is consumed during the welding process. In terms of equipment, it is the simplest, oldest and least expensive method of welding aluminum.