aluminum wire questions

[ssdavis70]

I have a Millermatic 251, and I need to know if I need to change my liner and tip to use aluminum wire, the current liner is .030 to .035.. os is using .035 aluminum wire pushing it to close? All help is very appreciated, thanks.

ssdavis70

[yorkiepap]

Aluminum....

Hey ssdavis70,
Yes, you need to change both liner and tip to convert to welding aluminum. The .035 liner will be the correct one to install and has to be teflon or nylon/poly. In addition, you must run straight 100% Argon for alum. and aluminum has to be welded a bit on the fast side and hot. Generally you should be in the 450-600 ipm range depending on thickness of material and gas flow in the 24-30CFH range. I use 5356 95% of the time because it's stronger than 4043, and feeds much nicer. There are occasions I do use 4043 because of the possibility of weld cracks on specific material. And lastly, cleanliness is the top priority to get good solid alum welds. Aluminum is quite finicky and a good SS wire brush and acetone or toluene will generally do the job nicely. Practice...practice...practice with alum.. You will get the feel of it and don't hesitate to experiment with your heat settings.....Good luck.....Denny

[Bert]

I got luckie and had the 30A gun included in the package with my MM251. I was told not to run alum from the machine itself, in fear it might kink up. I figured if I use just the gun for alum, I won't ever have to change the liner in my MM251...I guess it should be ok as long as your hose doesn't have a hard curve in it...I have a friend that tigs 1/4 inch alum with his 180, and didn't get penetration with 100% argon. Miller told him to use 75% Helium and 25% Argon. Can he use that with his MIG also?

[yorkiepap]

Aluminum parameters...

Hey Bert,
You were smart getting the spoolgun with your unit if you are going to be doing aluminum on a regular basis. Changing liners is not a picnic. That's why I have 2 MIG welders(shop/mobile) set up for alum.. I have never had a problem with penetration with 100%AR and I do 1/2" regularly for the company I work for. Sounds like the loss of penetration may have been from too low a heat setting. Yes, he can use the HE/AR mix on his MIG....Denny