To weld aluminum, clean the surface, remove the oxide layer, use AC TIG welding with a pure or zirconiated tungsten electrode, and select the appropriate filler metal. Utilize 100% argon shielding gas, preheat if necessary, maintain proper torch angle, and practice to improve control and consistency.
Aluminum is one of the most common materials in manufacturing; however, it is not commonly used in welding, particularly for beginners. The unique properties of this metal, which are very light, malleable, and flexible, make it great for other applications that require flexibility but are not ideal for an application such as welding.
However, following these tips, you can weld aluminum under certain conditions. Many advanced welders like to use aluminum for certain projects. Or they appreciate the challenge of welding a metal that isn’t usually welded.
Whatever reason you want to work with aluminum while you weld, here are some tips to make it work.
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Can You Weld Aluminum?
Although welding aluminum is difficult, you can weld it.
One way to do so is by combining aluminum with another metal to form an alloy. Alloys help combine the best that different metals have to offer. An alloy will cover up the weaknesses of each of the metals, creating a stronger substance. For aluminum, alloys make the metal stronger and more heat-resistant, especially when combined with sturdier metals. We recommend researching if an aluminum alloy is right for your project instead of pure aluminum and sourcing that instead, as the welding process is much easier.
You can also weld pure aluminum if you know the techniques to get around the metal’s quirks. Part of knowing how to weld aluminum is knowing why this metal is so difficult to work with.
One important factor is the oxide coating. Most aluminum is insulated by aluminum oxide, which requires higher temperatures to weld through, temperatures that could burn the aluminum underneath.
Getting the temperature right is difficult when welding aluminum, not just because of the aluminum oxide. Aluminum has a very low melting point but also conducts thermal energy thoroughly and does not show when it is melting. It is very porous, meaning that it absorbs impurities during melting easily.
All these factors mean that welding aluminum requires knowledge about the metal itself, insight into welding processes, and the ability to notice when something isn’t going right and adjust accordingly. If you want to try welding aluminum, ensure you have the experience to make it work.
Welding Processes Suitable for Aluminum
One of the most important things to decide when to try welding aluminum is the welding you want to use.
A few criteria determine which type of welding works best with aluminum. The process should have as little mess as possible to prevent metal contamination. Something like stick welding can work in a pinch but is not the best choice because it is messy.
It helps if the welding process uses filler material, such as flux. Using these materials makes it easier to detect when aluminum reaches the right temperature for welding.
However, you need to choose your filler material carefully.
Choosing the right method is also important because high-fuss methods, for example, types of welding that require manually feeding a wire as you weld, adding extra stress to a process already fiddly due to the nature of aluminum.
These are the best types of welding for aluminum:
- Gas Tungsten Arc Welding (TIG)
- Gas Metal Arc Welding (MIG)
- Beam Welding
- Resistance welding (only in special circumstances)
How to MIG Weld Aluminum
MIG welding is one of the most common types of welding, not just for aluminum but also for many different metals. This type of welding uses an electric wire, fed continuously into the welding machine, to form an arc between the electrode and base metal.
MIG welding is great for aluminum because it is fast and efficient, creating minimal opportunities for contamination.
Here are the basics for how to MIG weld aluminum.
Prepare your work area
Welding aluminum requires more preparation than most metals. Make sure that your metal and electrode are very clean. Prepare your shielding gas and make sure it is an extremely important gas, such as argon or helium.
Welding aluminum requires other equipment, such as heat sink and push-pull wire feed.
When MIG welding aluminum, most people recommend starting the arc about an inch before the welding point. Moving along the joint, move in one direction—pushing, not pulling. Keep a steady forehand angle and use a string bead technique.
Finish the weld
To finish off a MIG weld on aluminum, narrow the melting pool by quickly reversing the weld, then ending the arc. You want to avoid pockmarks if possible.
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How to TIG Weld Aluminum
TIG welding is another technique commonly used with aluminum. This technique, gas tungsten arc welding, uses a tungsten electrode. This automatically makes your life easier than MIG welding since you don’t have to feed in wire to act as an electrode, but the tungsten remains an electrode throughout.
TIG welding has a few other advantages that make it ideal for aluminum. It uses an alternating current, which helps strip the aluminum oxide and clean the material. It is ideal for thinner, more delicate materials such as aluminum.
Here is how to use TIG welding with aluminum:
Prepare your equipment
Ensure you have everything in place to weld, such as your electrode, alternating current welding machine, and aluminum. Clean your pure tungsten rod and aluminum ahead of time.
Prepare the electrode
Your tungsten rod should protrude only a little past the edge of the nozzle. You will hold it close to the aluminum for best results while you weld.
Add the filler material
Instead of using a filler wire, add the filler material to a puddle on top of the aluminum.
Ensure you have a constant supply of gas and argon flow to the torch to make welding regular throughout the process. Keep your machine at a steady angle and speed.
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Welding Machine Settings for Aluminum
No matter what technique you wind up using for aluminum welding, make sure that the settings are adjusted properly.
Since aluminum is usually thinner, make sure you adjust the machine properly. Experts recommend adding one amp for every 0.001 inch of the metal thickness. Depending on the technique, you may need to switch the amperage type. For example, TIG welding works best with AC current for aluminum.
Your heat point will also be different for aluminum than other metals, such as steel. Ensure you use a lower heat, around 1,200 degrees or slightly higher.
Welding aluminum requires some extra equipment. There are the basics, such as your electrode, welding machine, and wires, but here are the other important components:
Shielding gas is important when welding aluminum because it prevents oxidation. Make sure you are using an efficient gas such as argon or helium.
You want to thoroughly clean aluminum before welding it to prevent contamination since its porosity makes it more prone to this problem. Make sure you have plenty of cleaning materials on hand.
Whether using a filler wire or flux pool, you need filler material to weld aluminum properly.
Spool or push-pull gun
If you are using MIG welding, which uses a consumable wire as an electrode, use a gun to feed the wire into the machine instead of manually to save yourself some effort during the process.
Using a heat sink as you weld aluminum distributes temperature evenly around the material. Aluminum has high thermal conductivity, so you want to prevent heat from congregating in one place, causing warping.
Tips and Tricks
To optimize your experience while welding aluminum, here are some tips.
First, clean your aluminum thoroughly before welding. Strong soap and solvents can remove any surface impurities. Aluminum is very porous, so it is prone to contamination during welding. You can prevent this by cleaning.
It also helps to remove the oxidation layer before welding. That makes it easier to get the right temperature for welding aluminum. Use a brush just for cleaning aluminum to scrape off the oxidation layer.
Try to use a straight bead welding technique whenever possible. Straight bead welding is when you push or pull the welding beam in one direction without side-to-side movements. Consistency helps you achieve a smooth finish.
Finally, be careful how you store aluminum. Store aluminum sheets vertically when possible. Keep aluminum in a place where it isn’t exposed to contaminants.
Aluminum is a fussy material that is harder to weld than other metals, such as steel, but it is still possible to do. Choosing the right welding technique goes a long way. MIG and TIG welding are the best, as they minimize contamination and warping. With lots of patience, specialty equipment, and some experience, you can also weld aluminum.