Welding Tips and Tricks

This question might have already been asked but I'll ask it again anyway.
I'm welding production on aluminum boats, 5356, and they are using a 75/25 argon/co2 mix. My question is why would they use this instead of straight argon.
Also, I'm using a miller XR-alumafeed powered by the miller alumapower 350 with the xr pistol and for the life of me I have the hardest time getting my settings right. I typically weld on .090 as the thinnest up to 1/8. I was running at about 21 volts and 440 wire speed. My frustration comes when every time my gun has issues they switch it for a new one and this always throws my setting off. My latest issue happened after I switched over my drive roller in the gun and my wire speed went from 440 down to 390 to get the same results. if anyone has an explanation that would be great. Also if anyone has suggestions on what my setting should be floating around that would be helpful. I weld mostly lap and inside corner joints with no prep after being cut or bent if that is of any help.

Huh... I am very curious to see why 75/25 is used. That is very peculiar to me.

Farmwelding wrote:Huh... I am very curious to see why 75/25 is used. That is very peculiar to me.

Yup.. Sounds odd..

https://www.millerwelds.com/resources/a ... ding-hints

'The most common shielding gas for MIG welding aluminum is 100 % argon. Flow rates of 20 to 30 CFH (cubic feet per hour) are acceptable. C25 or argon Co2 mixes are not acceptable.'

Bye, Arno.

Sure its not 75 argon and 25 helium or hydrogen?

I might have miss identified the gas being used because it's a argon/co2 regulator, not a straight argon one.

The bottle label should have the analysis printed on it.

That regulator is interchangeable with 100% CO2, 75/25, and 100% argon (and other mixes), with only slight inaccuracies in the reading. The gasses and mix have similar densities and will read similarly at the gauge. It doesn't get significantly inaccurate until you work with helium mixes.

Steve S

Vulpine welder wrote:I might have miss identified the gas being used because it's a argon/co2 regulator, not a straight argon one.

What does the bottle say?

My question is: How's it working?