Kevin starts by sharing some of his, uh, mail, including an email from a viewer who asks, “How do I know how to set the amperage when I’m welding aluminum? What’s too hot? What’s too cold?”
Kevin is working on a sculpture made of 1/8″ aluminum box tubing, and he is going to test his amperage on some scrap metal. He has his TIG welder set up, his torch is ready with his tungsten sharp and clean. Then he’ll pick an amperage, any amperage, weld a bit, look at the weld, then adjust. You just
set the amperage high, then low, working toward the best setting.
That setting may change if you are going from, say, a horizontal butt joint to a vertical or a lap joint, so you have to get out your scrap metal again and test it once more.
Now it’s time to give it a run. Kevin has his AHP AlphaTIG 200X set at 100 amps, AC, AC frequency is at 120 herz, and the AC balance is at about 25%. He then welds a cut in the aluminum.
The first thing he notices is some little black specks in the weld. He had wire brushed the aluminum with a stainless steel brush, freshly ground the tungsten although it was used, and used clean filler rod. Kevin thinks the tungsten is contaminated, so he’s going to get rid of it.
Looking at the weld itself, you can see the cleaning effect on both sides of the weld. But the weld looks pretty flat, like it’s a little too warm.
Kevin is ready to remove the metal from the vise, douse it in the sink to cool it, and then turn down the amperage and weld on a different side so the welds can be compared.
He has a brand new E3 tungsten, freshly ground. He chooses a new side of the piece of aluminum, and cleans it with a stainless steel brush. He has the TIG welder set at 75 amps, and everything else is set the same.
After Kevin has finished welding, he shows how tall the weld is. He shows how flat the 100 amp weld is in comparison – that’s just 25 amps different. That’s how he figures out his amperage. He uses a piece of scrap metal just like the metal he’s going to weld on and tests it, going high and low, and narrowing in on the right amperage for the job.
Next he turns the TIG welder up to 88 amps and welds another section of the metal. The weld isn’t perfectly flat, but it’s flatter than the 75 amp weld, but not concave like it’s about to blow through.
Kevin shows the 75 amp weld again, then the 88 amp weld, then the 100 amp weld. He might adjust his amperage setting a little more, shifting to 87 amps or 89 amps. He’ll adjust how fast he welds, how fast he feeds it. Aluminum is much different than steel in that once you get started, it’s “off to the races.” You have to keep going or you’ll get a blow out.
He plans to set the welder at 88 amps for the rest of his project, however. The penetration looks good, while the 75 amp weld doesn’t have a lot ofpenetration, with the weld sitting on top of your base metal. The 100 amp weld was trying to crater, to blow right through. It was way to hot and too flat. If it’s too flat, there’s not enough filler, or it’s way too hot.
So do all your testing on a scrap of metal as long as you need to get the amperage set right. Then get to work! Like Kevin is.
Although you might want to stick around for a minute and watch Kevin get stuck ….