View Full Version : How do you clean aluminum before you weld?
03-01-2011, 04:25 PM
I needed to make a stand for few Villiers motors that need rebuilding, I scrounged up some scrap aluminum and had Joel weld it together. Well he complained about how bad it welded, well after changing tungsten size and the balance setting it worked much better. Afterwords he asked what flap disk or grinding disk was best on aluminum? Well I had given him a new zirconia flap, is that the best? This was painted and anodized aluminum scraps not clean / fresh aluminum, even was dirty a washed it down with purple cleaner (lye). tt
03-01-2011, 04:35 PM
I use a wire brush (That is NOT used for anything else) to clean the surface. I wipe it down with alcohol, acetone or lacquer thinner (whichever is available at the time) before & after wire brushing. I also wipe down the filler rod with the same solvent. I don't usually grind the tungsten when welding aluminum but when I do I use a grinding wheel that is used for nothing else but tungsten shaping. Cleanliness is a good thing especially when welding aluminum.
03-01-2011, 04:41 PM
After cleaning off all the dirt and paint (and whatever) with detergent and a stainless wire brush, I sand it with new clean sandpaper. Then a good scrub with acetone.
Most scrap I find seems to be 6061 which welds fine. Some aluminum doesn't like to be welded, 2000 series aircraft alloy for instance.
I gas weld it but I would expect the same prep will be good for TIG.
03-01-2011, 04:46 PM
Also, it looks like the welds are a little cold. I like to crank up the amps to get a hot start & then use the foot pedal to control the heat during the weld. Also, keep the arc as short as possible. That will help with penetration and will keep the bead narrower. I don't profess to be a pro at welding aluminum at all, I've only welded it a few parts for personal projects, but this has been my experience when welding the stuff. As thick as your aluminum looks you'll need a good deal of amperage, you might even need to pre-heat it a little with a torch.
03-01-2011, 06:21 PM
It doesn't appear that that aluminum has been anodized, just dirty. Scotch brite pads work well, files and carbides do well also. I have the feeling he has been hitting the puddle with the tungsten. Acetone is a good cleaner but its not really necessary.
Don't know what you have for a machine but most guys think you can go in like steel and strike an arc and then go. With older machines you learn patience and have to wait for the puddle. Once you learn that weldin luminum is a dream. Other things, where is the gas lense on that torch, cup size appears ok, but no gas lense? Spend the money and get one or two or three... Forget all the other kinds of tungsten, they say use pure. That sucks too, just use 2% thoriated, for what your weldin you mite get buy with 3/32" but would be better off with 1/8".
As for rod, use 4043 3/32" would be ok, 1/8" would probably be better and he'll learn patience, puddle should be nice and shiney before adding rod.
For the thickness of that aluminum, tacking in the outside corners is fine, but a little preheat would go a long ways to better welds instead of tryin to blast the weld in. A few minutes with a propane torch, hot to touch, no need for a big preheat.
03-01-2011, 06:36 PM
I use mechanical methods as well. file, sand, wire brush or wire wheel.
But if you want to go a step further, this will help with the degreasing and cleaning.
It works well, but it is EXPENSIVE..........
03-01-2011, 08:52 PM
Like the previous posts I use carbide bur, open lead type file, stainless brush and acetone. On real coroded or dirty aluminum the first thing I do is blast it in a sand blast cabinet then procede with the rest. I try to stay away from sandpaper or scoth brite to avoid the resin contamination. But it will still will clean up fine following the outher steps. Have known welders to use mag wheel liquid cleaner and stainless brush together. Hope this might help a little. ED
03-02-2011, 06:51 AM
SS brush, scotch bright, acetone.....
Cast Al, I set the AC balance more to the (+) side by 60%, pulls the impurities out....
I just cant get over the fact that Villiers engines found their way over to you.
In my youth I must have pushed all the things I ever encountered fitted with one of those things further then they ever propelled themselves.
We did you wrong, sorry about that.
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