The Black Art of TIG Welding Aluminum- Crash Course Edition

Tig Welding can be a black art if you start on your own with no direction. All too often we see first time TIG Welders struggle with the basics and this can lead to frustration and a long learning process. TIG welding aluminum can be more difficult than steel; even with a simplified TIG welder like the Eastwood TIG 200 AC/DC. Aluminum tends to be less forgiving and there are some simple steps you can take before, during, and after the weld that can help you successfully weld aluminum. I decided to throw together a few common mistakes and corrections for beginners when learning the “black art” of TIG welding aluminum.

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“Cleanliness is next to godliness”- Cleaning your weld surface and keeping everything you do as clean as possible when TIG welding makes a world of difference. This is even more important with aluminum, taking extra steps to clean your parts as good as possible will help you make a clean and strong weld. Above you can see a piece of “clean aluminum” that I pulled off the shelf and welded on. You can see the brown halo around the weld and spatter of dirt that was forced from the weld. In the grand scheme of things the aluminum was “clean” but not enough for TIG welding. The second a piece of bare metal is exposed to the atmosphere it starts oxidizing on a molecular level. This oxidation will take a while to be visible to the naked eye, but it’s happening. I suggest to at the least use a dedicated stainless wire brush to scuff the surface of the aluminum until you have a dull, brushed finish. You can also use a fresh sanding pad or disc as well. I then suggest to follow up with Eastwood Low VOC PRE, Acetone, or a similar chemical. DO NOT under any circumstances use a brake cleaner-type product as they contain a chemical that when heated or burnt creates what was once known as “mustard gas” and can be DEADLY. Our Low-VOC PRE and Acetone are safe to use, and are the preferred solvent to clean parts one last time before welding.

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You’re settings mean a LOT- Even on a simplified machine like our TIG 200 AC/DC the extra dials used for aluminum can be confusing, even more so if you’re learning on a higher end machine with lots of dials, switches, and “blinky gauges”. The clearance effect or AC Balance control is the most important dial to learn when welding Aluminum with your TIG welder. This dial will essentially change the “sine wave” of the AC welding process. This dial will change how long (we’re talking fractions of a second) the welder will stall on electrode positive to electrode negative to gain either more cleaning or more penetration into the workpiece. On the Eastwood TIG 200 this dial is called “Clearance Effect” and goes from -5 to +5. The more negative you go on the dial will net you greater penetration and a tighter arc/weld puddle, but less cleaning of the workpiece. If you go more positive the puddle gets wider and more cleaning of the base metal occurs. In this case the heat goes more into the torch itself. There’s a reasonable limit how far you can go positive on the Clearance Effect, much past 0 will cause the electrode to get overheated and start balling up or potentially fracturing at the end. You can see the pics above of an electrode that was overheated due to incorrect settings.

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There are a few ways you can “cheat” this setting. I highly suggest converting you torch gas nozzle and collet body to a gas lens to achieve better gas coverage and more efficient cleaning. The added shielding coverage when using a gas lens allows you to turn your setting more towards the negative side for a tighter arc and weld puddle. Cleaning your workpiece as much as possible can also help since the machine doesn’t have to work as hard to clean the metal. Also remember that there are many grades of aluminum which can change where you set the dial on the machine (IE- older low quality castings vs. fresh new plate aluminum).

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Wait for it, Wait for it- Patience is something that is tough sometimes, especially when you have so many things going on at one time when TIG welding. A big mistake we see beginner TIG welders make when learning how to weld aluminum is not waiting for the puddle to fully initiate. Like we talked about in the paragraph above, when welding on AC the welder actually cleans the base metal before the aluminum turns molten. This means you will have to wait a few seconds before a puddle starts. This time will vary on your amperage, clearance effect (AC Balace), and how clean your material is. Above you can see the process of starting a puddle in aluminum. At first the arc will turn a small circle of the metal white, then the area will increase in size and the “eye” of the puddle will begin get shiny and turn into a liquid. Shortly there after the puddle will open up and start to get larger. Once you have a puddle thats the desired size you can begin to add a dab of filler rod, move forward half the puddles diameter and add another dab of filler. Just make sure that the area is staying clean around the puddle and there isn’t black specks floating in the puddle or brown halos around the puddle.

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“Bad Form!”- How you hold the TIG torch is a lot more important than some beginners realize. The weld arc travels straight out of the electrode and the more direct its path can be to the workpiece, the smaller your arc will be and the less you’ll heat the base material up. A bad habit many beginners learn is “laying the torch down” when welding. This happens without you realizing it because you’re probably trying to turn it to see the puddle and tip of the electrode better. A good rule of thumb is to tilt the torch back 10-15 degrees from the way you’re traveling on the work piece (left to right for a lefty and right to left for a right handed torch holder). If you start laying the torch down too much on any material, the weld puddle opens up quickly and the workpiece heats up so much you could blow through the metal or the puddle grows uncontrollably large. On aluminum the other thing that happens is that the filler rod starts balling up or melting before you even try to dip it in the weld puddle and can cause a mess and a LOT of frustration. If you’re having this problem I can almost 100% bet you have your torch laid down too far. This can be a difficult thing to conquer when welding something that isn’t flat like round tubing or a wheel, etc where that 10-15 degrees changes as you rotate around the tubing. If you see your filler rod balling up too early or the puddle opening up try changing your torch angle mid-weld and see if that solves the issue. In the photos above you can see where I laid the torch down mid-weld and how much the puddle grew in size and then when I tilted it back up it slowly got smaller again.

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Don’t pull away!- Most of us learn MIG or ARC welding before we tackle TIG welding. These types of welding it’s perfectly acceptable to immediately pull your welder away from the workpiece as soon as you’re done welding. This is a big no-no with TIG welding, ESPECIALLY on aluminum. This bad habit can be tough to break if you’re use to these other types of welding, but it’s necessary to break if you want to make sure your beautiful stack of dimes weld doesn’t fail! A few things happen when you immediately let off of the pedal and pull your torch away from the weld at the end of a puddle on aluminum, the first being that the molten metal is left without shielding gas for a fraction of second in which it is now vulnerable to being contaminated by the air. The other thing that can happen is that the weld is “shocked” from going from hot to cold so quick in that it could develop hairline cracks in that last bit of weld that WILL spread (Crack is bad Mmmmkay?). The process that I’ve tried to get myself into over the years is when you get to the end of a weld puddle, add one last small dab of filler as you slowly let off of the pedal. Let the amperage slowly bleed off until its down to nothing, then hold your torch over that area until your post flow shuts off on your machine. This will keep the shielding gas flowing over that vulnerable last weld and keep it from developing a crater and a crack at the end. Above you can see an example where I let off the pedal very quickly and immediately pulled the torch away on a hot weld. Even on a short weld like this there are small fractures that are already forming, not what you want on anything you care about!

In the end nothing can beat practice and repetition, but if you’re conscious some of the common mistakes others make you can correct as soon as they happen to you. Take your time and keep some of these key steps in mind and you’ll be on a path to close-up worthy welds!

-Matt/EW

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28 thoughts on The Black Art of TIG Welding Aluminum- Crash Course Edition

  • would of like to see all he wrote on on a video .and showing some of the mistakes and how to over come them a lot of good in fo read it carefully and learned a lot thanks joe.

  • I appreciate the information. It’s been a long time since I’ve welded. With proper planning, studying, and of course practicing, the goal is to eventually enter the welding profession again. This is insightful and relevant. Thanks much.

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