Stainless and Miller 252

[rhubbard]

I'm trying to weld 20 and 22ga. stainless sheets. The 252 only gives settings down to 18ga. for stainless. This was my first clue.

I'm using Tri_Mix gas at 20 CFM and .023 wire. I'm using 17.5 volts and 150 FPM for 22ga. I'm burning the wire down to the tip, at times, and only intermittently getting a good ark. Getting a lot of popping and my welds have a brown soot on them.

The 252 goes down to 22ga. mild steel, I've noticed some of the smaller MIGs go down to 24ga. Would they be a better choice?

Is what I'm trying to do possible and practical?

Any help or suggestions would be appreciated, thanks!

[con_fuse9]

Whenever you are burning the wire back to the tip - not enough wire speed.
That popping sound, more like machine gun, less like sizzle - not enough wire speed.

Now if you up the wirespeed you will put more heat into the weld. wire speed is proportional to current so you are effectively upping the Amps.

Stainless distorts like mad anyway. Doesn't seem to get brittle when you quench (at least not if you let it cool down to non-glowing temps - say 1000def F). So you MIG in very short burts, And use a damp rag to cool it down.

Oh, and don't use tri-mix. Try 98/2 instead (or 96/4 AR/CO2). Tri-mix puts more heat into the material, something you don't need.

[c wagner]

I was going to say the same thing about the tri mix.
Even 75/ 25 will work fine, especially for something that thin.