Our welder always insists on preheating thicker aluminum plates before any welding. I understand that this is the standard procedure but sometimes I wish there was another way. We have a big weldment, about 4' X 4' plate 1" thick with bunch of square tubes and I beams welded to it and after machining we found couple of small cracks in the welds. If the whole thing is heated we will have to scrap it as it will warp and there is no way to remachine it. I thought maybe there is some other way to fix it? Jerry
Jerry, yes there is a way. Right now you would be using AC with high frequency and a pure tungsten electrode, right? Even with high amps, you will be unable to weld thick sections without preheat. Here's the trick and it works great. I used to have a production job on heavy alum that would require twenty minutes of preheat per part. I was looking into buying a very high amp welder 800-1000 amp to get around the preheat. The actual welding, after preheat took about a minute. Here's your solution. Get a tank of helium instead of the argon that you are now using. I used the same regulator for the helium as for argon. Now, for the electrode, use a thoriated, ceriated or whatever you use for steel. Polarity negative electrode, same as steel. No high frequency is needed. If your piece of alum is cold, you will see a molten pool of weld in a second or two. With this procedure I once welded a hole, without preheat on a piece of alum almost two feet thick in maybe fifteen or twenty seconds. It will take a little practice, so don't go directly to your expensive workpiece. The bead flows differant and may need wire brushing afterwards, but the strength will be there. And BTW, when the time on my production job dropped by 95% due to this trick I may have "forgot" to pass this savings along to my customer! Dixon
Jerry, you won't have the cleaning action you had with the conventional AC/ High freq method so clean the alum real good with a ss wire brush beforehand. You will notice a slight amount of skin (dross or slag) on the puddle, whereas with conventional ac the puddle will be clean and shiny. A wire brush afterwards will take care of it. email me if things don't seem to go right, I've been down this road enough to know the process. If you try this method, let us know how it went. Dixon
I'm trying to get our welder to use your way but it is a slow going. He is one of the guys that does not like to be told what to do. He knows everything better. Jerry
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