How to Feed a TIG Welding Puddle: Steel vs. Aluminum
A new TIG welder asked why he could weld steel pretty well, but with aluminum he was having trouble knowing when to start feeding the puddle.
Kevin shows what he sees when he is looking through his welding helmet. With steel, when you start your arc, you see the gray metal change to orange and then red. Red is where you want to start feeding with steel. If you keep pushing it, though, the metal turns white, which is when it falls through.
The colors tell you when to start dabbing with your filler rod, when you might need to back off the foot pedal, when you need to increase your forward speed.
When you're welding aluminum, though, when you start your arc, it stays silver. When you increase your power with your foot pedal, it still says silver. Give it a little more power, and you start to see little, shiny pockmarks.
But don't feed yet! Give the welder a little more pedal and all of a sudden you see the little pockmarks start to run together. Still, don't feed it yet! Give the welder a little more power and all of a sudden everything goes shiny. Now start feeding!
And it's off to the races. You have to keep up because now the heat is starting to spread throughout your aluminum, traveling forward the way your torch is pointing. Feed it! Go, go, go! Run! You have to keep up with it. If you go too slow, all of a sudden, the metal falls through.
And you won't get a warning. Every now and then, it will sag a bit before it falls through, but usually you get no warning. And if it's a small bead, all of a sudden you have a big hole you now have to fill.
Now Kevin puts on his safety equipment and heads to the workbench. First, he TIG welds aluminum. You can see the metal start to get shiny, then he pushes on the pedal a little more, and you can see the big liquid puddle. Now feed!
With steel, the minute you put any amperage to it, it turns red and you can start feeding right away.
After he finishes TIG welding, Kevin shows the steel bead and the aluminum bead.
Kevin is ready to go back to work, but you might stick around one more moment to see Kevin Caron do the critter crap-out ....
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