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!

[aa5gp]

I'll have to take some pics. They are on the dry docked vessel and not here. The stubs were welded on the tubes prior to boring and bearing installation to avoid distorting the barrels with heat. The struts are 20 in long. I fitted the tubes, tacked the struts to the tubes, tacked some angle across the struts close to the barrels, cut the struts off approximately 6 in from the barrels, welded the strut stubs to the barrels and took them to the lathe for boring and bearing installation. I miked the tubes before and after welding the strut stubs and they didn't distort. Since I had 4 sides to fillet, I would only make a single pass on a side before switching off to another side.

[weld_13]

im not shure about the pushing. ive never tried it because im used to using a stick welder mostly and that a big no no to mess things up with a stick welder.

[Sundown]

As far as I know aluminum gmaw should be pushed, sounds like you were loseing voltage in the push mode for some reason, maybe one of the more techey guys knows how that could happen. That sure sounds like a job for a 350P or a Dynasty 700 to me. Pictures will be interesting to see as the thickest aluminum I have tackled was 1/2" to 3/8" and it was doable with my MM210/3035 spoolgun & my Dynasty 200DX (just bearly).

[yorkiepap]

Hey aa5gp,
I do a lot of cast and extruded alum. and I believe you can do that job with your equipment if you do some practice runs on scrap the same size. You will have better results with 5356 and .035 minimum wire size. I have a similar setup as you with a 3035, SGA100 and Challenger 172. For a start, go to 85 heat and 85 wire feed with 25cfh of argon and maintain 1/2-5/8" wire stickout. If your unit doesn't go into spray, up the heat to 90, then more gradually if necessary. You should be running 550-600ipm minimum of wire feed to achieve spray mode. Maybe more.... You will get better results with a preheat of 350deg. and the metal has to really be CLEAN. You can accomplish the job with multiple passes but risk cracking. If you are going to stay with 4043, definitely go to .035. Let us know how you make out....Good Luck....Denny