[Otto Nobedder]

I get the impression that part of our perception of Skepsis' posts come from a language barrier.

He did mention he's not a native speaker.

I'll grant that these are fair questions, as there is some confusion in the posts he quoted.

I'll see if I can get Chris' attention by e-mail, and ask if he wants to weigh in on this (though it's a daunting read at this point).

Steve S

P.S. Despite our perceptions/inferences, no rules have been broken that I can see. The questions have been far more "matter of fact" lacking emotion (the language barrier?) than combative in any way. I'll be interested to see where this goes.

[soutthpaw]

I know a couple pros that are really good at DC aluminum TIG. I just got a tank of helium myself, Got some hands on help from one of the pros. I just need a bunch of practice at it. The arc and the weld pool look much different from AC TIG. Just need to.play with it more. Only do it for fun anyway.

[chadwilliam1]

Thanks OP. I just did some DC tig on aluminum with 4043 and It came out pretty good. I am interested in to try it on something heavy.

[Nikolai]

Hi,
I have a DC only machine and after some learning on steel I'd like to try aluminium .
Somebody mentioned a bit of argon in the helium helps clean the puddle . Will a 90/10 He/Ar mix work ?


Cheers

[johnnynightstick]

I like using nouns as verbs and adverbs.

Since his profile says he's from Munich... I would say English is not his first language.
English and German share similar grammar but they can be very different.
No need to be childish. You end up looking like a jackass.


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[Oilman]

I saw some discussion here wondering why Helium/DC welding gives greater penetration yet seems to be a "colder" weld.

I certainly don't grasp some of the physics going on here. This is in the realm of plasma/gas interaction physics.
I suspect that this is a simple function of thermodynamics. Aluminum is a fast conductor of heat. (we all know this) Helium has a much higher ability to carry heat before becoming ionized. Therefore, heat is transferred into the base metal faster than other shielding gases. This is why welding aluminum with helium requires less amperage vs argon. So the heat is more concentrated in a smaller area giving greater fusion penetration. It is a "colder" (welds solidify quicker) weld however because the surrounding metal has not absorbed as much heat over time/distance form the weld and will act as a quench to the heated/molten area.

This can be clearly observed with cut and etched samples of DC welded aluminum. The root fusion is awesome.

I am currently welding aluminum tanks for my business. I got pissed over failed welds from our company supplied equipment. I suspect the supplied equipment was MIG welded and poorly executed. All of the failures were lack of root fusion. They might have well stuck the plate together with JB weld. I have added a small amount of helium in with argon and off the cuff find the welds look better and seem to be a bit easier. I will have to check to see if root penetration is better. While I am using an AC inverter machine I just might have to learn to DC weld aluminum.

[MarKlane99]

I have worked in the high-tech field and have used DC aluminum welding on most of the products we have worked on. The process provides a greater penetration on thicker parts, so it is primarily used when these parts are to be machined down. It is almost incomparable to AC when doing this, because AC welding has a tendency to crack when grinding or machining the welds down, especially when welding a smaller or thinner part to a larger, thicker part. This isn't the case with the DC process. This is why we have preferred it.