[infernoST]

Hi all
If you're using a multi process machine (Mig/Tig/Stick) that is a DC only machine why can you weld aluminum using a spool gun on the mig process but not on the tig process? This has me a bit confused.

Thanks

[Farmwelding]

Spool gins still use DC power because it is a wire feeding that requires a constant voltage supply. AC tig welding is needed for cleaning action on aluminum. Technically for small repairs you can use DC on aluminum if you do it right and it's not for structural welding aluminum.

https://www.millerwelds.com/resources/a ... ce-control

[RamboBaby]

I've been wondering the same thing and the only thing that I can come up with is maybe because it's a spray transfer process which is exponentially hotter than short circuit process. You can tig weld aluminum on dc with pure helium and at much lower amperage than with argon because the helium makes the arc nearly twice as hot as does the argon. It's also a much cleaner weld than argon.
That's all I got but it's just a guess.

[infernoST]

Thanks for the reply Farmwelding. I'm new to this and am going to purchase an Everlast PowerMTS 251si which will be my 1st welder which is DC only and while doing my research many say that you can't DC Tig aluminum which makes doing your welder research that much harder, I guess I will get the spool gun down the road and play with the tig aluminum.

[infernoST]

I've been wondering the same thing and the only thing that I can come up with is maybe because it's a spray transfer process which is exponentially hotter than short circuit process. You can tig weld aluminum on dc with pure helium and at much lower amperage than with argon because the helium makes the arc nearly twice as hot as does the argon. It's also a much cleaner weld than argon.
That's all I got but it's just a guess.

I was getting the same thing from my research about using helium but there is even a debate about that in certain circles. I'm gonna order my Welder then experiment and continue to do research on it.

[RamboBaby]

Ask to speak to technical support at Everlast. I can't remember the guy's name but he is very helpful and he can most likely tell you the answer to this question. I believe he does the repairs on defective units.

[infernoST]

Will do, Thanks RamboBaby.

[RamboBaby]

I just found the answer. It's because with mig its all electrode positive (cathodic etching only happens on the positive side of the wave form with tig) so your base metal is being cleaned 100% of the time.

[Oscar]

Yea with MIG, the spoolgun (just like solid steel wire MIG) works on DECP, which is what provides the cleaning action while at the same time melting the electrode/wire into the puddle. You can't do 100% DCEP on a DC-TIG because even though you'll have cleaning-action, the tungsten will not be able to handle all that heat, and will quickly deteriorate/melt. It has a high melting point, but not that high.

Now, you can do DCEN on aluminum, but you need Helium for that, and it is a very specialized process that an amateur/beginner will likely not be able to master easily/quickly. Besides, you still need a lot of amperage for welding aluminum.

[infernoST]

Thanks guys for the follow up and additional information