Helium

ACID_RAIN28

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Question #1 I have been told that you can weld in DC with 100% helium on aluminum, no preheat, heats up faster than ac? Another opinion was to use 5% helium with argon and it would be a cleaner weld. The last ideaa was that argon was for preheated aluminum and helium was for cold welding?

#2 where did the term heliarc come from some say it was a torch manufactuer and others say that it came from using helium with the welder?

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AZmiik

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GTAW or TIG welding was originally developed using He and the inert shielding gas and yes it was termed Heliarc. This was also a trade name/mark of the developing company. According to my book here. "Helium is more expensive than argon. Its lightness is also a disadvantage, since it has a tendency to rise from the weld very rapidly. Two or three volumes of helium are required to give the equivalent protection of one volume of argon. Thus helium is consumed in larger quantities. Increasing the cost disadvantage. Furthermore, since argon is denser than helium, the use of argon materially reduces the amount of space required for cylinder storage. More heat is liberated at the arc with helium than argon. Welds of deeper penetration a produced and welding is faster. Helium is preferred. Therefore, for the welding of thick sections of steel and for metals with high thermal conductivity such as aluminum and copper. Argon, on the other hand, is used extensively for welding thin sections and dissimilar metals. Its low thermal conductivity results in a weld deposit with a relatively wide top bead. (Sacks 1981)"
It goes on to say that Helium produces a higher arc voltage which results in a hotter arc, deeper penetration and higher welding speeds. Helium is also used extensive in automatic welding.

Nothing I have seen says anything about not using proper preheating procedures when welding with Helium and a shielding gas.

Mike
 

ntsqd

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What AZmiik said plus:

Try a red tungsten when going DC, but grind it square ended. It works a whole lot better than with a green. Only place I found this technique to really pay off was in really thin stuff.

TS

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Dave_G

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Re: "Try a red tungsten when going DC, but grind it square ended"

I use the reverse polarity trick with a penny. Makes a really nice radius mushroom tip on the tungsten for welding aluminum. ;-)

Dave

"I know it all, but I can't remember most of it..."
 

ntsqd

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At school we had this nice hunk of 2" hex copper to do that with. First time I've heard of using a penny. I'll file that for future ref.
On the thin stuff I usually step down to a 1/16th electrode (instead of my patented, read: lazy, long taper grind) and don't bother with balling the tip right away. In a few inches it balls up pretty good. If it is something critical, like the fairing supports for the HPV, then I'd ball b4 starting.

TS

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ACID_RAIN28

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let me get this right... If i decide to go dc with the helium on aluminum just square it off with a red head?
My boss when he is laying down a bead on 090 or simmilar aluminium he grinds 3/32 to a point then fires it off and gets a tiny ball, and of course perfect beads, go fiqure, 20+years experience!!

I understand the cost of helium and the fact that it takes about 2-3 times as much, but if i get better penetration and higher quality welds than it is worth it! THANKS

A LAZY MAN ALWAYS WORKS TWICE!

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ACID_RAIN28

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also I have been using 3/32 on about .100 on the wall thickness, do you all think that it is to much or should i go thinner like 1/16 on the electrode?

I too am a member of the patented "lazy grind"

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ntsqd

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I found I got a more consistant ball by using the 1/16th than taper grinding the 3/32. I suppose I might try taper grinding the 1/16th if the material were thin enough. Ultimately I think it's a matter of what works for you, rather than doing it the "Correct" way, what ever that is.
A gas lense will help out on the shield gas consumption and give you a better bead.

TS

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BradM

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3/32 will work but you will get more control using a 1/16 tungsten for thinner material. I usually make the switch from 3/32 to 1/16 somewhere around 0.050-0.060 material thickness for Al. If you use a 1/16 tungsten for thicker material it begins to melt away as the current level goes up and the size and shape of the ball becomes harder to control. That is where you can get the advantage of a 3/32 tungsten and start with a tapered grind. The size of the ball on the end will be a function of the current levels that you are hitting and it will give good control to your bead size/shape. When you get down to material much under 0.030, try a 0.040 tungsten.
 

AZmiik

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Just a couple of things to remember. The balled end of the tungsten should be no larger than 1 1/2 dia. of the tungsten. While helium might yield greater penetration the more aggressive arc will be hard to control and then to do more harm than good on thin sections. It was stated that it is best used on thick sections. By thick the author means thick like 3/4" and up. Not to discourage but the welding industry has spent millions of dollars and man-hours the figure these things out so the welder doesn't have to.

Mike
 
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