[Xtapolapocetl]

I'm new to TIG, I started less than a month ago. I got some aluminum strips to practice on, and so far one thing that happens consistently is that the strips (about 2mm thick) warp every single time I try to put down a string of beads.

The aluminum is most likely 5052. I have 4043 filler rods, at the moment only 3/32" thick. I use 1/16" pure tungsten electrode. I set the current to 55A, A/C. It takes a few seconds to get the pool started, and then it gets really wide really quickly. I try to turn the current down a bit, with varying success (matter of practice, I guess), but by that time, the metal is already bent out of shape.

What is your advice? Should I start at a higher current to get the pool started quicker? Will I need to do short runs with cooling in between? Is this how you normally weld aluminum?

[Oscar]

Small strips are the worst to practice aluminum welding on, for the very reasons you stated. It's because of aluminum's heat sinking ability. On small pieces a few inches long, you'll only be able to run one short bead, maybe two, before the whole piece is completely saturated with heat. That is why the bead gets really wide really quickly---the whole piece is darn near at the melting point of aluminum---so wherever the arc strikes for the next bead, it's literally melting through. The smaller the piece the higher the amperage you need to start out with, and the shorter the bead you will be able to run---nothing you can really do about it at this point if you insist on practicing on the same small pieces. The smart thing to do is to practice on the largest piece you can find, but not overly thick. Even then you'll have to stop after a little bit of time to let it cool off. Which leads me to the next point----get several pieces to practice on. When you see one piece start to get too hot (if the initial bead flares out almost immediately), then it's time to set the piece down, and get another piece at ambient temperature. The more of these you have, the better, because you can just set one down, and grab another one that will be cool.

For the time being, crank up the amperage so that the puddle is established in one second or less. The longer you wait around for the puddle to appear with low amperage means that the heat is simply dissipating into the WHOLE piece right before your very eyes, without you knowing it. Get the puddle started quickly, and please put down the 3/32" filler rod. You'll have a much easier time with 1/16" filler. Feed it in as soon as the puddle turns into a "mirror", and move right along, reducing the amperage with the foot pedal as necessary. You have to move quick, or you'll just be trying to fight the same issues over and over and over again.

[TamJeff]

R6 or R11 framing clamps are your friends. If you are going to do any fabrication at all with aluminum, now is a good tome to get acquainted with them. Clamp your thin pieces to thicker pieces or make a purge plate out of steel to clamp them to, or something rigid, welding table etc.

[Xtapolapocetl]

Following the suggestion from the first reply, I ordered a few 1/8" thick plates from eBay. In the meantime I can try clamping the strips I have to steel plates. So far I've been clamping them directly to the welding table (a small portable one), and it was getting so hot that it was hard to rest the hand with the torch on it after a while.

Are the R6 clamps like vise-grip C-clamps? Google shows me lots of pictures of the Yamaha R6, but no clamps. I found your other thread that mentions them---are those the clamps behind the wooden bar?
http://forum.weldingtipsandtricks.com/v ... f=5&t=2689

[TamJeff]

Yes, they are the vise grip type framing clamps. The R6's are the small ones and the R11's (the ones in the photo) are the bigger ones. That's not wood. It's a piece of 2"x2"x1/4" aluminum angle with old masking tape on it. Clamping the strips to something thicker also helps to sink the heat better. As you can see, even the larger pieces of aluminum warp, which is why I have that backer bar clamped to it.

[newschoppafowah]

+1 to all the heat sink advice.

I had to make a number of 12"x10"x8" boxes with lids out of 14 GA 5052 (now in your career is a good time to learn that the gauge references are different for aluminum vs. steel, if you didn't already know)

I went and bought a copper drop from a local supply house, cut a corner out of it all down one side and used it as a heat sink / argon trap.

Cut down on the waiting between welds and helped to prevent contamination from atmosphere on the back side.

Being that it was a drop, I didn't get hurt too bad on the price, the time I saved was well worth it and I have it now in case I find myself in any similar spots.

The size of your filler wire makes a big difference in cooling of the puddle too. No harm in experimenting with 16th, 32nd, and 1/8th all on the same size base metal. You'll pick up how this affects things in a hurry. If it were me, I'd get sure what my base metal was and get the right wire. It's not a big deal now but it's a good idea to get used to filling 5052 with 5356 and 6xxx with 4043. They act a bit different and when you're learning you want to minimize dancing around between the variables you have control over. Just my 2 cents.

[Xtapolapocetl]

Ok, so I tried higher amps (75, then 70), and I clamped the aluminum to a steel plate about 5mm thick. I also did shorter runs, and the warping was much reduced.

Here are some pics:







I noticed that the time it took to get the puddle started would vary from spot to spot. I'm guessing this was because of differences in the contact with the steel.

[mcoe]

Not bad, just keep up the practice.