Is AC required for aluminum welding?

[d4ve]

I was looking at the weldall series and the weldmax series and I noticed in the comparison chart that the weldmax are DC only and will not weld aluminum where as the weldall are ac/dc units and will weld aluminum. Other than that the units seem to be equivalent. Is AC the key to being able to weld aluminum? Does any body know the science behind that?

Thanks,
Dave

[Gadget]

Yes you need AC. AC is a square or sine wave. On one side the current flows to the metal heating it up, on the other side of the cycle the current flows to the electrode. The flow to the electrode breaks up the oxidation on the aluminum which has a much higher melt temperature than the aluminum. This cleaning action is needed to get the oxidation off allowing direct access to the aluminum puddle. Without this cleaning action the aluminum will melt under the oxidation and you can't do anything with it.

[atcig]

That was very interesting and informative. Thanks Gadget.

[gilly]

That was very interesting and informative. Thanks Gadget.

I 2nd that.At least now I can explain it to someone else if they ask.

[tomsign]

There is a way do AL in DC not as good and not pretty but it can be done.
But Gadget is A on

PS just not worth it. Go with AC

[arandall]

Yes you need AC. AC is a square or sine wave. On one side the current flows to the metal heating it up, on the other side of the cycle the current flows to the electrode. The flow to the electrode breaks up the oxidation on the aluminum which has a much higher melt temperature than the aluminum. This cleaning action is needed to get the oxidation off allowing direct access to the aluminum puddle. Without this cleaning action the aluminum will melt under the oxidation and you can't do anything with it.

Thanks Gadget. That's the best explanation of the concept I've seen. It makes more sense to me now.

[Gadget]

It takes a simple mind to explain it simply

[tigqk]

Their are some that can weld aluminum with DC using helium, but the metal is extremely clean.That is all that I can confirm about the subject as their is so little of it done because of the difficulty involved for those reasons posted above, this mix is also refer to as hot mix because of the additional penetration procided by it.

[rustycase]

Seems it could be done with dc, but AC is the ticket.
It was a major factor in deciding which machine I would purchase.
...couldn't make that level of investment and disregard the option of working with such a common material as Al.
rc

[WookieWelding]

DCEN with alum is by no means for the beginner and is for 1/4 inch and thicker alum requires a grade 5 helium i am currently working on mastering this process