How Do You Weld Aluminum?

Welding aluminum is a bit of a challenging task even for experienced welders. There are several scattered sources of information regarding aluminum welding and many manuals that are available also carry scant meaningful information. There are few basic welding books but with very short sections on aluminum welding. Even today most welders learn aluminum welding more through a method of trial and error.

Equipments needed

First let us look at the equipments needed for aluminum welding.

Tungsten Inert Gas (TIG) welder is by all accounts, ideally suited for welding aluminum. It is said that aluminum can also be welded with a MIG welder or a stick welder or even a with a gas torch.

Good quality durable welding glove are essential if the welder wishes to avoid suffering from the painful blisters. Equally necessary is a sturdy welding helmet and market reports suggest the gold tinted auto darkening helmets as the most suitable.

Argon or Argon / Helium mix gas is required and it is nearly certain that mixes of other gases are not fit for aluminum welding. Another important fact to know is - using the tank from the MIG welder on the TIG welder will not work.

The welding rod prescribed by many for aluminum welding is 4043. It is necessary to have a separate dedicated stainless steel brush exclusively for use for aluminum welding. It is also preferable to have a special metal bench to help put out a fire while welding.

It is preferable to have a squirt bottle with water - not so much for cooling the work, as for putting out small fires without using a fire extinguisher. Please be aware that any attempts to hastily cool aluminum may result in crack in or near the weld.

Last, but not least in importance, is a heavy long sleeve cotton work shirt. It is pertinent to note that TIG welding produces more UV radiation than any other welding process. One would also need clamps or vise grips and some blocks or bars of aluminum or copper to use as heat sinks.

Useful Welding Tips

Clean the aluminum and this is a very necessary step that should not be overlooked.

Here is how to prepare the aluminum for welding: 

  • spray the aluminum with little carb cleaner or electrical cleaner.
  • rinse the aluminum in water, just in case there's any nasty residue.
  • use a stainless steel brush to scrub the aluminum shiny clean around the area to be welded.

There is a suggestion that the aluminum should be scrubbed in one direction only to avoid working contaminants into the aluminum. It is also reported that 3M scotchbrite pads are a good way to prepare aluminum for welding.

Clamp your work to a heat sink made of copper or aluminum as using a heat sink under the area to be welded will absorb some of the heat and help keep the work from warping. Preheat the area before welding as this makes it a lot easier to weld aluminum.

If the tungsten gets contaminated, then stop welding and fix it. When the tungsten gets touches the weld pool or the filler, the arc becomes unstable and the weld quality goes way down. Fit the parts together as tightly as possible leaving no gaps. This is somewhat hard to do when welding aluminum with the TIG. Use one amp per .001" of material thickness. Set the amperage a higher than the maximum you expect to use and use the foot pedal to back it down. It is advisable to use a filler rod size equal to the tungsten size and adjust the tungsten to project from the hood a distance roughly equal to the diameter of the tungsten. The arc length should be roughly equal to the diameter of the tungsten.

The tips furnished herein are by no means complete but there are many informative articles available on the Internet for beginners in aluminum welding.