OK, I'm wondering here, some of the more expensive TIG machines allow you to set the balance such that you have 90% EN and 10% EP in AC mode for aluminum. That 90/10 balance is awefully close to straight DC EN. I'm just wondering what would happen if you tried welding aluminum with straight DC EN. Has anyone tried it just to see what would happen? I'd imagine you get some black oxidation on the bead, but figured this is worth asking...I should have tried it when I was at the demo rack Friday, but the question didn't occur to me then...
Dave
DCEN welding of Al is in fact a not uncommon procedure. The whole issue being that you need to remove the surface oxide layer and commence welding before it has substantially re-formed.
This procedure is normally done with chemical removal of the oxide layer just prior to welding. If you have the right set-up and handling / logistical procedures in place, then this is actually the better way of welding Al, because you are getting most of the heat into the base metal and not the electrode.
Regards
Niekie Jooste
Thanks for the post! So, assuming the metal is visually clean, is scrubbing with a stainless steel brush immediately before welding sufficient?
Regards,
Dave
Dave-
I use DCEN and helium quite often. Most every time I am welding any al thicker than 3/8inch I use DC and helium. A number of welders try 75%helium 25% argon w/ ACHF or even 75 He/25Ar w/DCEN. Yes, there is some black residue along the toe of the weld. It takes some practice to recognize and manipulate the helium rich puddle. Great penetration and attractive weld bead when performed correctly.
I'm glad I asked this question. With all the sophisticated AC square wave TIG welders on the market, an inexperienced newbie like me would almost assume that you can't weld aluminum with DC...<g>. Thanks very much for the posts, you guys are saving me some money now that I see I probably don't truly need an AC and/or square wave machine for what I might be doing with aluminum (pretty simple stuff).
Q: Why helium rather than argon?
Dave
Dave-
I would still buy an AC/DC TIG/STICK machine with HF. You will need AC w/ HF for all sorts of mat'l combinations, thin to thick when welding al. Helium adds more heat energy to the welding arc than argon alone. Arc characteristics are different and helium is much more expensive than argon. I own a Lincoln SquareWave 175 TIG/STICK and like it very much.
Good point. I remember reading somewhere that, on AC units with balance control, that you set it more EN to get more penetration on thicker material, and set it more EP for less penetration and wider bead on thinner material.
Thanks for the answers on helium vs. argon.
Dave
Dave, AC is also very valuable on older, dirtier Aluminum. You will find the cleaning action on the positive side is often necessary when welding anything other than very clean or new material.
Respectfully,
Mike Sherman
Shermans Welding
Listen to Mr. Sherman here!
Don't buy a machine without AC if your planning to weld a variety of aluminum. While DC- with Helium is nice and puts a ton of power into the work, there are plenty of componants you will run across that can't be welded DC. You will find with aluminum (especially castings) that "visually" clean means nothing! Aluminum prep is a topic in itself and one too lengthy to be fully treated here.
As to the AC with balence control at 90% DCEN with aluminum you will not find any application without helium unless you also have variable control of amperage on each side of the AC half cycle.
Frequency in Hz. much like balence control I would not want a machine that takes the control out of your hands. Vairable frequency in AC aluminum is over rated unless your working with very thin stuff <less than 0.063>.
Lastly, price out a bottle of helium before you buy.
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