Aluminium welding with MIG - Help...

[pk999]

Have a Sealey MightyMig 130XT, am using argon gas, have cleaned weld surfaces and earthing surfaces with grinder just prior to welding, and am using max 2 setting, with 0.8mm wire at 8 speed. Sections to be welded are 3mm box. All I have managed to do so far is attach large blobs on the surface and achieved no penetration. Have varied, speed, power settings and gas flow. all do little to help. Any clues please gentlemen (apart from buying an AC TIG set)?

 

[malcolm]

Welcome. There are a couple of pages here for setting the welder up for aluminium and then welding aluminium with a MIG. It's funny stuff and tricky with a MIG, though blobs shouldn't be the problem.

Grinder will probably run too hot and would probably cause the alu to corrode again instantly, otherwise mix the oxide in. You'd be better off with a stainless wire brush. Have a read of those pages first though - I reckon the answer will be there.

 

[shenion]

For 3mm you will probably want the welder on the highest setting. You may not have enough wire speed.

It will start cold for the first 1/3 inch of weld.

Use a 3/4" torch/work gap, torch near perpendicular and a push travel.

0.9mm wire will work better as it puts in more heat. It will also use a slower wire speed.

 

[matt1978]

I fear your machine is probably not big enough.

The Blobs you describe, will most likely just be the weld material sitting on the parent material, as you said, not penetrated at all.

Is there any way you can pre-heat the Aluminium first before trying to weld?

 

[pk999]

Gentlemen,

Thanks for the tips. I was using a small tip to work gap, as I assumed this would be more amps - but it would appear I had it the wrong way round... I have a propane torch, so will try pre heat, and just the brush to clean. Will let you know if I crack it. (no pun intended)... Thanks.

 

[pk999]

Follow up:

Finally achieved satisfactory welds using max power (2max) and fastest feed rate (10), cleaning the weld areas just with a steel brush, and moving the gun pretty fast, with max gas flow. As a matter of interest Sealey say that 3mm aluminium is the max thickness the 130XT can cope with. Welds are not pretty, but seem strong enough... Thanks for all your help.