Learning to Weld: 3 Tips for Welding Aluminum

Aluminum is one of the most popular metals for welding projects. It’s lightweight, sturdy, and accessible. This makes it a good choice of metal for experienced and new welders alike. However, aluminum can be a tricky metal to weld, even for experienced welders. As with all metals, there are certain tips and techniques that work best for welding aluminum, and knowing how to weld with aluminum can make your experience much better. Here are some tips for anyone who would like to know more about welding with aluminum.

Aluminum Uses

First, let’s take a quick overview of the type of welding projects for which aluminum is good. Because aluminum has a relatively low density compared to other metals, it is a popular choice, so it is used for a lot of items that need to be relatively light without sacrificing sturdiness. This makes it particularly useful for things like bike frames and even air and space crafts. It can also be found in more common items like door and window frames, pots, pans, and golf clubs or baseball bats.

Challenges

The main reason aluminum can be troublesome even for experienced welders is oxidation. Aluminum is notorious for having a thin layer of aluminum oxide on its surface. This aluminum oxide requires a much higher melting temperature than the aluminum itself, which can complicate any welding project. Because the oxide layer melts at such a high temperature, it is easy for any welder to inadvertently burn through their aluminum underneath the oxide layer if they are not careful.

TIG vs. MIG Aluminum Welding

The two main welding techniques used with aluminum are Tungsten Inert Gas (TIG) and Metal Inert Gas (MIG) welding.

TIG welding is commonly used for thinner sheets of aluminum. TIG welding is the preferred method for welding thin sheets of aluminum because it makes use of an alternating current, which can safely clean off the oxidation layer from the aluminum’s surface during the welding process, and also keeps the aluminum free from contamination. TIG is a popular and effective technique for many sensitive metals like aluminum for this reason.

MIG welding aluminum is preferred when your aluminum sheets are on the thicker side. The recommended cutoff for MIG welding is 18-gauge aluminum (0.04” thickness). Any aluminum sheet below 18-gauge should be welded using TIG, while anything over can safely be MIG welded, though beginners may still want to use a higher threshold.

When it comes to aluminum MIG welding, it’s important to make sure your filler rod and base material are clean and free from moisture. Because MIG welding does not offer the same protection against contamination as TIG welding, the welder must take greater caution to prevent contamination when using this method. Particularly, it is important for the welder to try to remove the oxidation layer from their aluminum sheet when MIG welding. If this layer is not removed before the weld begins, it is too easy to inadvertently burn through your aluminum, which will only cause frustration and wasted materials.

Spool Gun

One last key tip to keep in mind when MIG welding aluminum is that you will need a soft wire. MIG welding is most commonly used for welding steel, but steel is a much harder metal than aluminum. If you try to use the same wire for both aluminum and steel, you will inevitably run into problems with tangled, or “bird nested” wires. One common solution for this when MIG welding with aluminum is to use a spool gun, which holds a shorter length of wire but keeps it from bunching up during the welding process.