Aluminum is a metal that reacts quickly with the air surrounding it. When aluminum is processed it can form a layer of oxide which can protect it from corrosion. This is one of the secrets why aluminum lasts for a long time. This quality of aluminum however can also make it very likely to react with the air that surrounds it, as one proof of how quickly it can react with the air, aluminum shavings can catch fire especially when mixed with steel shavings. Now when it comes to working with aluminum, using TIG welding for aluminum sheets is relatively easy, but MIG welding with aluminum is much more difficult.
When you to weld aluminum here are some tips that you can use in order to ensure the quality of your work:
Remove the Oxide- As we have mentioned already, aluminum forms an oxide layer so your first step is to remove that layer from the surface that you are going to work on. Use a stainless steel brush to clean the surface, and for the edges use a file. Use a brand new brush and remember to brush in one direction, you do not want the oxide being rubbed in to the surface. The thing with oxide is that it has a higher melting point than your aluminum sheet. That means it can really mess up your work if you don’t remove it thoroughly.
Welding- You must have guessed by now that welding aluminum is a lot more tricky than working with steel because it melts at a relatively low temperature and conducts heat really fast. It is very easy to create welding holes on it and yet if you are too cautious your welding might be ineffective. The best practice is to use the same setting for steel and move the gun really fast over the area being welded.
Heat Sinks- You can use heat sinks so it can absorb most of the excess heat generated by the welding process. You can clamp the sinks to the back of the aluminum sheets. The best metal to use for a heat sink is brass. With a heat sink attached it can absorb a great portion of the excess heat allowing you to work at a much slower pace. With a heat sink attached to the pieces that you are working on, you can weld aluminum in the same way that you work on steel.
Push the Torch- When you are working with aluminum the best practice is to hold the torch at a nearly vertical position and then to move it away from you. That technique can result in a much cleaner weld.
Alloys- Aluminum sheets are never made from pure aluminum. These sheets are alloys, with aluminum mixed in with other metals most notably magnesium. This makes welding them somewhat easier than with pure aluminum rods or other aluminum pieces.
Aluminum Welding Machine- If you are planning on buying an aluminum welding machine remember that TIG welding is the process best used for aluminum. Though a TIG welder can cost a lot more money than the other types of welding machines, it is the best kind to buy for aluminum welding and in general I’d say if you could only afford one welding machine, then a TIG welding machine should be the one you choose.
These reminders should come in handy when you are planning on doing some welding work with aluminum.