Too much metal for too small a machine?

[aa5gp]

I have a Millermatic 180 and a SGA100 with a 3035 spoolmate gun. I'm having trouble getting the wire speed and voltage adjusted correctly for an aluminum project I'm doing. I'm welding 1 in aluminum plate to 1 inch thick aluminum pipe. The plate is beveled to 45 deg as I require 100% penetration. I've preheated to 240-250 deg f. My wire is 0.30 4043, the voltage is set @ 80-100, and the wirespeed is set @ 50-55. My gas is 100% Argon set @ 30 CFH. My problem is maintaining spray transfer while pushing. When pulling, it isn't a problem. I just leave a dirty bead which requires much more grinding prior to the next pass. When I push, I get a great deal of spatter and I can't stay in spray transfer mode; It goes into short circuit transfer and spatters terribly which requires even more grinder work. I realize I have too small a machine for this job, but I though I could get by with multiple passes, careful grinding, and cleaning between passes. BTW, Miller doesn't give the IPM for the SGA100 in any of their literature so I can only guess what my current is. I used the recommended settings from the SGA100 manual for 1/4 thick aluminum. I've considered going to an argon/helium mix to reduce my voltage drop but I'm only stabbing in the dark at this point. Any suggestions would be much appreciated. Thanks

[MAC702]

Aluminum requires more heat than steel. You have too much aluminum for that machine, IMO. What is the wall-thickness of the pipe?

[aa5gp]

The pipe is 12 in long, 4-1/2 OD, with a wall thickness of 1in. The flatbar I'm affixing is 6 in wide and 6 in long.

Thanks...

[MAC702]

Wow, that piece is going to get seriously hot while welding that thickness. The heat has no where to sink to.

I can't address whether or not warping is going to be a problem. That thickness for that short is a rare project.

Curiosity demands asking what's it for?

Do you have pieces to practice other settings with, or does this have to be perfect the first time?

[aa5gp]

It got hot. I would turn down the voltage and wirespeed as it heated up. The tubes are marine strut bearing barrels (Johnson Duramax cutlass bearings). for an aluminum hulled boat. I had two of them to fabricate and I worked on them for several days. Each side required approximately 35 passes to fillet completely. I have them complete now and have since bored them to spec and pressed the bearings in. I was just confused as to why I had so much trouble maintaining spray transfer while pushing.

Charles

[MAC702]

...I have them complete now ...

So let's see 'em!