mig welding aluminum

[bipolarandy]

I need to weld a piece of Al but all I have now is 25% co2 argon mix , what will happen if I use this ? do i need pure argon?
-Andrei

[aametalmaster]

Yes pure Argon is needed...Bob

[jeremy k]

What process are you using? mig/tig - yes pure argon on both

[Dodge]

Mix will contaminate the weld. It will have black deposits in an around the weld and generally be a poor quality weld. Basing this off memory of about 5+ years ago, so if anybody wants to confirm or deny this....

[Hillbillysmith]

It will have black deposits either way you go, but you are right Dodge. It will contaminate the weld if there is any CO2 in the gas. So, use pure argon.... If I remember right, I think you can use argon mixed with Helium. As long as it's an INERT environment you'll be good. I just did aluminum MIG today, but I used 100% argon.

[Thomas Dean]

I had to qualify some alumn. weld procedures sevral reays back and we found that a tri-mix gas was the best...92%argon, 6% helium, and 2% sorry I can't remember. But Hillbilly is correct also with a argon/helium mix, and argon is the most accepted shield gas. When welding thick alum., especially 3/8" and up, preheat by first using a flame with little or no oxy., then adjust flame correctly and heat until all the black is gone. Once at this heat you will find the welding is easier and faster.

[KYBOY]

We always used pure Argon. Switching the liner in the mig gun line from a coiled liner to a teflon liner sure makes the fragile aluminum wire feed easier. Not nessasary but nice. I much prefer that to a spool gun for aluminum. I use to work for a company that made Aluminum Coal truck beds. "Coal Buckets" as we call them here in Ky..

[bipolarandy]

Thats some great info guys , thanks alot.
I guess its another tank with pure argon for me

[Dodge]

Another thing we found was using a gun that had rollers to pull the wire thru rather than the machines rollers pushing the wire thru helped. Not with contamination of course, but with overall weld quality and preventing malfunctions. Expensive, but we had less jamming at the rollers. Aluminum wire, being softer than steel wire, has a tendency to "catch" inside the liner, especially if there is a sharp or tight bend in the liner. We would try to keep the liner stretched out and as straight as possible to prevent any binding.

That'll cost ya another 4 cents

[bipolarandy]

i bought a spool gun with my welder, havn't had a chance to use it yet because i dont have a second tank...