TIG welding is an ideal welding process for aluminum since you have so much control over the heat and metal filler application. You can take your time or crank it up as needed without warping the aluminum or piling on unnecessary metal.
The basics of welding aluminum with TIG are pretty well-known, such as cleaning your work piece and watching your amperage. However, some TIG welding situations are unusual or particularly demanding for welders, especially with aluminum. Here are some pointers on how to adapt to particularly challenging aluminum TIG welding situations:
What Kind of Aluminum is It?
When you don’t know what kind of aluminum you’re working on, you’ll need to do some research and test welds in order to figure out if the aluminum pieces can be joined together in the first place. This is a good reason to keep scrap metal around for tests. If possible, do some practice welds with scrap metal and a part of your work piece that will be easy to grind. Let it cool and then see if you can break it off easily.
If you can’t figure out what kind of aluminum it is or how to join it together with a lasting weld, you may need to consider other ways to join it together, especially if someone’s safety will be at stake.
You’ll have a bunch of questions to consider as you perform these tests: Will the weld joint crack later? Will the aluminum work pieces get too soft if they’re heat treated? How do you know you’ll get enough penetration and fusion in the weld joint to make a strong enough weld?
Don’t Grind Aluminum Down Too Far
Getting your aluminum clean is good, but don’t distort the metal or make it weaker by cleaning it too much. Sometimes the practical use and strength of the metal is more important than getting every last bit of paint cleaned off. Grinders can do a number on your metal work pieces if you’re not careful.
Get a Good Ground
It’s common welding knowledge that you need a good ground in order to weld without your arc jumping and making all kinds of sparks and spatter. However, this is especially true for aluminum. Your arc will suffer if you don’t have a good ground, and it will wander all over the place, sometimes hurting the fusion of your weld.
Using a piece of scrap copper or higher quality grounding clamps will help you get a better ground when you weld and keep your arc tight and focused on your weld joint.
Don’t Let Your Tacks Get Too Big
A couple of solid tacks will help hold your work pieces together so that you can create a strong, tight weld, but blasting too much amperage into the joint will distort the metal.
For tacking aluminum, avoid adding too much filler to your tacks, if any filler metal at all. As you weld, keep an eye on your arc, as it may wander from one side to another. Good tacks and a focused arc will keep the metal from becoming distorted or out of position as you weld.
Know When to Lay Off the Heat
TIG welding isn’t all about heat and filler metal. Oftentimes you’ll need to slow down a little and work on refocusing your arc. Take your foot off the pedal if you can’t get both sides to melt evenly so that you can straighten things out. You want good fusion on both sides when you add the filler metal.
In addition, blasting too much heat may distort the metal and prevent the filler from melting down into the root so that it fuses together. Don’t just dump tons of filler metal on top of the weld joint. That’s a sure way to create a weak weld that will crack over time when it comes under pressure. In addition, too much heat will make the metal buckle and will weaken it.