How to Weld Aluminum: The Ultimate Guide

Aluminum can be a tough metal to weld, requiring TIG welding, but we’d compiled the ultimate guide for you. TIG welding by itself takes practice to learn, and aluminum is a soft metal, which can be even harder to successfully weld than thick metals.

How do you weld aluminum? In order to weld aluminum, you must use TIG welding, a form of welding that uses gas to protect your weld instead of flux.

TIG welding is a skill that must be taught by a craftsman, however, we’ve compiled a variety of tricks specific to TIG welding aluminum. The next time you need to weld some aluminum, try our guiding suggestions and let us know how it goes.

The Ultimate Guide to Welding Aluminum

Your first step towards welding aluminum is to learn TIG welding. We’ll cover a brief overview of this, but you should wait to try this until you’ve had some experience in some form of welding from a professional or long-term hobbyist. Welding can be dangerous, and a proper foundation is key to safely learning more processes.

If you need a quick overview of what TIG welding is, there’s a short section at the end of this post covering what it is in relation to working with aluminum.

Once you’ve learned TIG welding, it’s just one step further to master welding aluminum particularly. The real key here is to practice the tricks we’ll be showing you. Your first attempt may not be successful, or not as successful as you like, and that’s all right.

We have several tips and tricks for welding aluminum specifically. Because it tends to be such a thin metal, some welders struggle to avoid burning through, achieving smooth lines, and properly finish each weld. If you have any of these struggles or more, look and see what advice we may have for you.

  1. Watch Your Hand Position While TIG Welding Aluminum

It’s hard to keep your hand consistent, especially when you’re trying to operate them each independently, as we’ll go into later. This is why it’s so important to watch your hand position while operating the welder.

You should brace your hand against whatever surface you’re working on, with the outer side of your hand down. Confused yet? The outer side of your hand is where your pinkie is. Bracing your hand against your workbench or table keeps your weld steadier, which in turn looks better.

You shouldn’t angle your torch very much, as a steep angle with give you an uneven, oversized pool to deal with. You’re also more likely to overheat portions of your metal. Instead, keep it almost completely straight, with just a slight tilt backwards so you can see where you’re going.

Don’t be scared to go for it. You shouldn’t need to practice over and over on scrap pieces of metal; if you have the extra metal, however, go for it, as practice will only make you better. If you don’t have the extra metal, however, don’t overthink it! TIG welding is still welding. Once you’ve welded before, the next time is easier.

  1. Be Consistent in Your Distance While TIG Welding Aluminum 

Keep the same distance between your tungsten and your workpiece to maintain a better weld. If you get too close, you’ll overheat the metal and cause it to discolor, marking the ruin of your weld. This is important in any welding method, but especially so when working with aluminum.

Aluminum is such a soft metal that you can easily overheat it. It may take you some time, practice, and burnt aluminum, but you’ll eventually find the correct distance to keep your tungsten from the workpiece. Once you find it, stay consistent with it.

Keep in mind though, the distance you keep between your workpiece and welder may change from project to project. Different metals may require more or less space, but so may varying thicknesses of metals. Thicker metals may require you to get a little closer.

You want to prevent any arcing from happening. This happens when you get too far from the piece, and the electricity is allowed to arc up visible, usually growing too hot at the same time and overheating your piece. The simple solution to an arc is to get closer to the piece.

  1. Keep Your Hands Separate When TIG Welding Aluminum

Most people instinctively do the same thing with both hands, if they’re using both hands. However, with TIG welding, they’ll be operating independently.

While one hand has to be dabbing in filler rod, the other has to maneuver the welder as smoothly as possible. This is difficult at first, but we have some tips on how to make it a bit easier the next time you TIG weld.

  • Practice, practice. Everything with welding comes down to practice, and this is no different. Your first and best resource is simply to keep going. Don’t be too discouraged if you aren’t quite getting it from the beginning, as this is common.
  • Use your hands separately often. You don’t have to practice welding to work on getting used to doing two things with your hands. Do you text and do anything else with the other hand at the same time? You’re already there! Now, try it with your welder instead of your phone.
  • Meditate and practice yoga. Operating your hands independently is a mindful matter. Strengthening your mind with meditation and stretch your body in different ways with yoga. Yoga can also help you focus on moving different body parts independently.
  1. Be Careful of Your Temperature when TIG Welding Aluminum

Part of the reason welding aluminum can be so tricky is because of its conductivity and how well it will hold heat. We’ll go into how the conductivity can cause issues and what to do about it in the following section, but first, we’ll go into how well aluminum will hold heat.

Typically, the piece of aluminum you’ll be working with will be thinner than standard sheets of steel or other metals. As we already discussed, this can make it easier to burn through the metal, destroying your piece. But one thing new welders tend to forget is how hot aluminum stays.

Aluminum holds heat for a long time. It’s one of the best assets of this metal, but in this case, the metal holding the heat can cause you to be more likely to burn through accidentally. To avoid this, don’t go back over sections of your weld until it’s cooled, or if you do, be very careful of how hot it’s getting.

Conductivity plays into this by conducting the electricity from the welder so well. The heat from the welder’s electricity being able to conduct itself through the piece of metal can be potentially damaging to your piece as well. To avoid this, take a break now and again so you aren’t charging the particles in the air near the weld so much.

  1. Aluminum is Very Conductive When TIG Welding

Aluminum is a very conductive metal, meaning it allows electricity to pass through it easily. TIG welding utilizes electricity to melt the metal, which is part of why it’s so great for aluminum. Because aluminum is so conductive, the welder is able to melt the metal more easily with the TIG than other metals.

Some welding machine comes with current control, meaning a control knob for how strong the electricity coming from the machine into the metal is. These can be very helpful for TIG welding, especially aluminum, as they allow you to turn down your current whenever your piece gets too hot.

With TIG welder without a current control, you’ll have to be more careful. The current will get stronger the closer to the weld you get, but it will also get stronger and start arcing if you pull away. Arcing is caused when there’s too much electricity being put out with nowhere to go.

It’s easy to cause arcing because of the conductivity of the aluminum. Be careful of this, as it will ruin your piece by arcing everywhere, along with being dangerous. Arcing frequently causes burn through, another reason to avoid it. If you begin to see arcs, simply get closer to the weld.

  1. Remember to Clean Your Piece of Aluminum Before TIG Welding

Aluminum is covered in varying alloys, some of which have a lower melting point than others. This simply happens by sitting in the warehouse before the store purchases it, sitting in the store before you purchase, and sitting again before you purchase it, even for a few hours.

It isn’t difficult to clean your metal before you weld, but it is crucial to the quality of your weld. You want to make sure every last bit of debris is off your piece before you attempt to weld. Otherwise, you’ll end up with bits and pieces of varying alloys that have varying temperature needs in your weld.

The pieces of alloy, if not cleaned off, will settle into your weld. This will leave discoloration, spots, streaks, and lower the strength of your weld. Even if the alloys are melted together in the weld, you’ll be able to clearly see the varying ones. Some will also have overheated, mixed burned metal in as well.

How to Clean Your Aluminum Before TIG Welding It

To clean your piece of aluminum before working on it, first, simply degrease it with something. Acetone works great, and you won’t have to wash it off after using it like you do with degreaser, but you can find other solvents as well specifically for cleaning aluminum for welding.

Next, you’ll want to clean off the surface. You’ll need a stainless-steel brush or some kind of acid. If you have a brush, don’t use it for anything aside for this. Using it on other projects will contaminate the brush against aluminum. Once you’ve cleaned off any debris, rinse and dry it.

From here, you’ll be able to weld your piece easily and shouldn’t find any alloys from the metal’s surface in your weld. If you do, you know to clean your piece further next time.

You can also clean your piece before you’re ready to work on it, as long as you protect it. Obviously, this won’t last forever, and if you wait weeks to work on it, you’ll need to clean it again. However, for a couple of days, you can clean your piece of metal, cover it, and leave it.

  1. Preheat Your Aluminum for TIG Welding

Just like you preheat an oven to ensure even baking, you need to “preheat” your aluminum piece. This is especially important with large, thick pieces of aluminum. Because the metal is so thick, it can be difficult to melt efficiently if you don’t preheat it.

To preheat your aluminum piece, you’ll only take them to 200 degrees Fahrenheit, maximum. Anything hotter than this, and you’ll be breaking into the chemical strength of the metal. Aluminum shouldn’t ever be heated past 300 to 600 degrees Fahrenheit at the end of your welding session.

The final temperature on aluminum should be around 450 degrees Fahrenheit. With thick pieces that you’ve preheated, it’s easier to get all of the metal there at the same time than just with the welder, which will have to penetrate each layer individually.

If you have a smaller piece of aluminum, you don’t even need to preheat. Preheating will help your weld’s integrity, of course, but it isn’t required in this situation.

  1. Always Push Your TIG Welding Gun Away from Your Aluminum Weld

Imagine your TIG welder as having two labels on the gun, one saying pull, the other saying push. You can use it either way, but there’s a secret to using it on aluminum. For your best aluminum welds, make sure you are pushing your TIG welding gun away from you.

This will not only give you better gas shielding, but it will also allow you to see where you’re going with your weld better than pulling it towards you will. It will also help you move slowly, smoothly, and with limited disruptions. You won’t have to reposition so much if you’re pushing it forward.

Pulling your welding gun towards you tends to cause people to move less smoothly, leaving a rougher weld. Instead of the perfectly straight, smooth line, you’ll end with something a bit more crooked and lumpy. You also won’t get the full benefits of the gas shielding.

Remember to keep your tip working in small, careful circles. You want to move your pool of melted metals along, allowing it to melt along the way. You don’t want to push too fast, or you won’t have as high quality of a weld. You can’t rush here if you want a good weld.

  1. Keep Up the Speed While TIG Welding Aluminum

We just said not to rush your weld, didn’t we? No, you don’t want to rush your weld, but do you want to complete it rather quickly. Unlike steel, which has a higher melting point, aluminum melts fairly quickly. If you linger too long, you’ll only cause a burn through.

How do you keep your pace fast enough to prevent burn through, but slow enough to keep a smooth, easy line? This is the part most welders struggle with the most when working with aluminum. It’s all too easy to get it too hot or be too scared and leave it too cold instead.

Unfortunately, there is no simple formula fix for this one. Instead, you’ll have to do some trial and error. The speed you work at when working with aluminum comes down to you and your welder. Some people simply work faster than others or have a welder that runs hotter.

Next time you weld aluminum, pay attention to how hot seems to be too hot. Are you moving too slow? Or check your weld. Is it holding strong, or did the metal stay too cold because you rushed it? Keep past experiences in mind to help you have an idea of where to start every new time.

  1. What Kind of Gas Should I Use for TIG Welding Aluminum?

Typically, argon gas is used in TIG welding to form a shield around the ongoing weld. However, some welders will use helium or a mix of helium and argon. Using helium or a high-helium mix is referred to as heliarc welding instead of TIG welding, as you aren’t using tungsten inert gas, TIG.

When welding aluminum, there isn’t a set gas you have to use. Argon is considered the standard “best,” but some welders prefer a mix of argon and helium for aluminum and other metals. Not only is argon the traditional choice, but it also seems to work best for rejecting airborne contaminants with aluminum.

Another option is to mix some helium in. This will both help your overall cost and your weld by preventing magnesium oxide, a compound that discolors and weakens welds. If you’re working with aluminum alloys instead of regular aluminum, helium may be a better option, as alloys are more prone to magnesium oxide.

Whichever gas you choose, be consistent with it. You don’t want to constantly change what kind of gas you’re using because your weld won’t be consistent. Each gas protects slightly differently, and you may find discoloration between welds made using a different gas.

  1. Choose the Correct Filler Rod When TIG Welding Aluminum

Filler rod is used in TIG welding, at least for the majority of the time. You certainly can choose to not use the rod, but traditionally, you will. What you choose to use for your filler rod can make a major difference though.

Typically, filler rod is made of the same material you’re welding or a similar one. With aluminum, you want to choose something very similar to what you’re working with, only a bit stronger. This will help compensate for the strength lost in the heating process.

Adding the extra metal with strengthen your weld significantly, especially when you purchase a rod of higher strength metal. You want to be careful, however, to stick to the same general kind of metal. If it’s a different color, obviously, you’ll be able to see it.

You also need to think about melting points. Aluminum shouldn’t be heated past 600 degrees, so don’t choose something that will require a lot of heat to melt, or you’ll burn through your aluminum before you even melt your filler rod.

  1. Change Your TIG Gun Liner Before Welding Aluminum

Your welder has a liner inside the “gun,” the part of the welder you hold and manipulate to create the weld. These liners are typically disposable and not very expensive, so you should stock up. It’s important to use the same liner for the same kind of metal or get a new liner for a new metal.

You don’t want to cross-contaminate your TIG gun liners with other metals because that will ruin your weld. All of the alloys from your previous projects still live inside that liner, just waiting to come out and land in your weld as you’re going.

You should change your liner often, even if you aren’t switching between metals, because of how much alloy will build up in them. They’ll start to get rougher and cause you issues while you’re attempting to weld.

Aluminum Requires TIG Welding

TIG welding is a specialty process of welding, which is typically used for softer metals such as aluminum or copper. If you already have a full or even basic understanding of TIG welding, you can skip this section. If you don’t understand or have a strong understanding of it, continue reading this part.

TIG welding is a specialty welding, only used for a select few things. Mainly, it’s only used for soft metals such as aluminum or copper. Because these metals are more prone to overheating, denting, and tarnishing, you want to ensure a higher quality weld than you may with a heavier piece of metal.

TIG welds are more resistant to cracking and corroding, a common issue with soft metals. This is because the unique process used in TIG welding allows the filler rod to retain more of its structural integrity on a base level. Metals that have been heated extensively will lose theirs.

For those who don’t have any background in TIG welding, we’ll do a quick overview of what it is, where you learn it, and what you may do with it before we get into welding aluminum specifically.

TIG Welding: A Quick Overview on the Welding Process for Aluminum

TIG welding stands for tungsten inert gas welding, also called GTAW, gas tungsten arc welding. In this method of welding, you use a non-consumable tungsten electrode to weld and a gas, typically argon, to shield your weld. Most other types of welding use flux instead of gas, as we’ll go into in the following section.

TIG welding requires the welder to both operate the machine and feed filler rod in between the pieces. This can be difficult to master and takes longer than other welding processes, which is why it’s only used for welds that are important to keep strong over a long time.

To be used, you’ll move your TIG torch in small circles, creating a pool of melted metals fusing together. You’ll add filler rod as necessary from the front, with the aim of keeping the weld as smooth as possible. It’s important to note to be careful of keeping the filler rod inside the gas, against oxidation, as you work.

TIG welding takes many people a while to master, as it can be a very technical, tedious task. TIG welding also takes longer to complete, as the entire process is significantly slower than other methods. However, for thinner metals and important pieces, the time is worth the sturdy weld.

The Inert Gas Shield Used in TIG Welding

We’ll delve further into the gas shield and what gas is best for using with aluminum, but as we just covered the basics of TIG welding, it’s only fitting to go into the gas used in TIG welding. This is run by a machine separate from the welder, connected by hoses that regulate the gas.

One of the signature characteristics of TIG welding is gas, as we remember TIG stands for tungsten inert gas. This is because unlike other welding methods, which use a gel or spray containing flux electrodes, TIG uses gas to protect the weld.

The gas forms a shield around the welding area, protecting your weld from airborne contaminants and oxidation. These two are what will leave you with red, black, or other colored stripes in your weld.

Without some form of protection, your weld will be prone to discoloration and weakness caused by airborne particles being attracted to the electricity produced by the TIG welder. The metal is prone to oxidation as well, because of the use of electricity, which the gas also helps protect against.

Alexander Berk

A bit about myself: I am a certified international welding engineer (IWE) who worked in different welding projects for TIG, MIG, MAG, and Resistance Spot welding. Most recently as a Process Engineer for Laser and TIG welding processes. To address some of the questions I frequently got asked or was wondering myself during my job, I started this blog. It has become a bit of a pet project, as I want to learn more about the details about welding. I sincerely hope it will help you to improve your welding results as much as it did improve mine.

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