[Adam Mc Laughlin]

Hi Everyone

WHAT is the best gas for TIG welding aluminum?
I hear conflicting answers:

Pure Argon ??
75/25 Argon Helium ??

Any advice?

Adam

[Rick_H]

Pure Argon is the most common unless you are welding very thick alum and need some extra penetration then the helium mix is appropriate

[Adam Mc Laughlin]

Hi Rick

OK. So... What is thick Aluminum and what is the mix you would use then?

I.E. if I had to put a transmission case back together or a cylinder head?

Adam

[Rick_H]

I consider 3/4" - 1" to be thick, and then I still preheat the piece....however, I have used it on thinner materials and it does help but it is a lot more costly and not needed. The price of helium right now is expensive.....

When I have used it the mix was 80/20. So I would say depends on what welder you are using, and what thickness you normally weld.

[eric325]

I heard somewhere that pure helium gives you the best penetration is this true??

[Adam Mc Laughlin]

THAT is what I was told....

Adam

[Braehill]

Adam,
I would say that the best cover gas to weld Aluminum is the cheapest that you can use and still get a suitable weld. Most times Argon would fit that bill perfectly. If your welder isn't large enough to weld a certain size with straight Argon, then a mixture of Helium can extend the size range a small amount. That being said, you still aren't going to be able to weld 1/2" plate with a 180 amp welder.

Any more than 50% Helium starts to cause the arc to suffer, as Argon ionizes better than Helium. Helium adds alot to the price and most times is not required. But if you have money that you need to waste, you can weld all things Aluminum with straight Helium, that's where the name Heliarc comes from, the original cover gas.

Len

[Adam Mc Laughlin]

Hi Len

Thank you for the very informative reply!

I have a friend whom owns a machine shop and he repairs aluminum heads and blocks with a 250 amp machine. I think it is a Panasonic machine or something like that; an Asian brand that is large and green.

I personally use A Synchrowave 250 at my house, and this is the biggest that I think I can run with the available current that I have. 220 V at 100 A
Occasionally I have a transmission case to fix, something like this. I am also a tinkerer or sorts, was wondering what the best way to assemble aluminum was. I do a few odd jobs here and there for people ( actually something per week ) and I am thinking that if I have the tools and ability at the house.... I will find more uses for the gear once it is here.

We all know how that goes!

Adam

[Braehill]

Adam,
You can always preheat Aluminum to increase the thickness that you're able to weld. Transmission cases and cylinder heads for the most part are not all that thick. They're large casting, but made up of mostly thin sections throughout. Heads can be put in a gas grill and transmission cases can be heated with a rosebud or even a small propane torch if preheating is required.

Residual oil in the cast is a bigger problem than their actual thickness, and no cover gas can help with that, but a preheat will.

Len