[DMCForum] GTAW and "Heli-arc"

["checksix3" <jetjock11@xxxxxxxx>]

>Helium and heli-arc really aren't used that much any more if at all. 
I would say 99% of the shops use TIG or GTAW (Gas Tungsten Arc 
Welding) which uses a tungsten electrode and 100% pure Argon 
shielding gas. With a TIG you can weld mild steel, SS, Al, and I have 
been told Cu however I have not tried yet.<

Hold on there Sparky. As an experienced GTAW weldor with a $4K 
squarewave inverter in my garage I need to correct you on this. 
Heliarc *is* GTAW. TIG is just the common shop name. Heliarc is 
exactly the same as tig and GTAW. It's simply the original name for 
the process. It's a trade name of Linde Corp, who bought the process 
from the two guys who invented GTAW, and they still use it. As you 
said, Argon is now used as sheilding gas for most work. However, 
Helium (or an He and Ar mix) is still very much used for welding 
thicker materials when better penetration or tighter arc control is 
desired.

Aluminum can easily be welded with Argon and usually is unless it's 
over 3/8 inches in thickness. You need AC current to weld aluminum no 
matter what gas you use, it's the positive part of the cycle that 
breaks up the oxides. Pure tungsten electrodes are only used for AC 
and aluminum welding, not for ferrous metals. And these days pure 
tungsten for AC has been replaced by zirconiated electrodes. 1.5% 
Lanthanated works for everything and is what I usually use.

And yes, you can weld Cu. It normally requires preheat as it sucks 
the arc heat away from the weld area. Most metals, dissimiliar or 
not, can be Tigged. (There are a few exceptions however.) Very thin 
stuff too, I often weld pepsi cans together just to stay sharp.

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