Did you know that using a 50/50 mix of argon and helium shielding gas will make any aluminum weld better?
Especially the thick stuff.
Really, Its like adding another 20% of amperage.
That really helps when you just barely have enough amperage.
I have a miller dynasty 200dx and for really thick aluminum castings, It just does not have enough balls.
But When I add helium along with a preheat on the gas grill, suddenly , I have enough amps to get the job done.
..and another benefit is that it welds cleaner too.
And another tip...Did you know that you can do some aluminum welding jobs with DCEN and straight UHP helium for shielding gas? If the metal is pretty clean.
UHP stands for "ultra high purity". and thats what you need. Not the stuff they fill balloons with.
I remember one particular job that this worked on was an fishing sinker mold.
The mold was made from heat treated 7000 series aluminum and the guy did not want to lose the hardness from the heat treatment.
All the mold needed was a small fill of a dinged area.
So we Hooked up some UHP helium, increased the flow rate to about double what I would have used with argon, lit up , puddled, added a drop of aluminum filler rod...and done.
No pitting, and the mold barely got hot.
But there is another use for helium, helium mix that is... if you have a small inverter welder that only puts out 100 amps or so and you have some pretty thick steel to weld. Using a helium mix makes it penetrate a lot better. Sometimes even too much if you are not careful.
Remember, Helium gas is what they used to use all the time...