Miging Aluminium

I would like to get set up for welding aluminium with my mig welder just incase the need arises . My mig is a SIP Autoplus 180amp, uses .6 or .8 wire I have argon, what else do I need plz? A teflon liner? I can buy some grade 4043 wire, would this be a general purpose wire? I dont know alumin grades.

Don't bother, you need the very miniuim of 250 amp DC for Ali with a MIG 350amp would be better.

0.6mm Ali wire is sooooooo thin it sticks inside the liner, whatever you use. Even when using a 350+ machine that can use +1mm wire, they tend to use hand spools.

It's possible with smaller MIGs. There's some reading on:
http://www.mig-welding.co.uk/aluminium-setup.htm and
http://www.mig-welding.co.uk/aluminium-welding.htm

I thought I had added some notes from Shenion on that page. He used a 5356 wire which is stiffer and less prone to birdsnesting. 0.8mm would be the smallest wire you'd want to try.

There are a number of threads on the forum that might be useful too.

We have a 180a mig set up for ali welding. Teflon liner, Ali drive roll (not completely necessary) . Welds like a champion... has done for years.

So, the higher the grade number the harder the wire? Would 5356 be usable as a general purpose wire or would it only do for 5356 alumin if this exists? Thanks very much.

^ 5356 will work with most of the common alloys, a poor match for alloys containing much in the way silicon (that'll be most castings). 4043 is usually considered the closest thing there is to a general purpose wire (with regards to hot cracking sensitivity).

While 4043 is softer, actual weld metal is typically lower in strength than with 5356 and more brittle. 4043 turns a manky grey colour if anodised, 5356 can suffer from corrosion cracking issues when subjected to elevetated temps

Properties and common applications of aluminium alloys
Filler selection and a bunch of other stuff

Edit. I'm with Shox Dr for the most part on this. Thinish (say under 3mm) Al and MIG is not fun, especially if after neat and/or air tight welds. Makes far more sense for thick sections but then you need a big machine

Yes, I found 1/8" easy on a small mig. Lots of fiddling with settings, wire speed and technique to get it right. I have done 0.090 (2.2mm) with the Clarke 130 and was doable with a steel backer.

hotrodder makes a good point. 4043 and 5356 work ok on aluminum stock. I tried a casting with 5356 and had cracking issues as it cooled too fast (preheat would have helped.) 4043 was too hard to feed on my 4m torch (only time I miss that 2m torch on the Clarke.)

The corrosion cracking with 5356 is hard to pin down. Many sites just say not to be used at elevated temps. I have seen users that swear by 5356 on repairing aluminum heads and have never seen a problem. I did find one table that implied the temp problem was using 5356 on 6xxx grades.

It is doable and can be good for production. I would want an 180+A MIG though and a spool gun if I was doing more than just an occasional fix. It starts cold, so air-tight welds are difficult.

I have not messed with MIG on alum in a long time. I have sice picked up a used AC/DC TIG and never looked back.

I worked for a transport refrigeration company some time ago, who used aluminium MIG quite a lot. To get around the cold start / hot finish issue, we used run-on and run-off tabs which were then removed after welding.

The welds never looked especially tidy, but they were sound enough. The frameworks carried 3 and 4 cylinder diesels coupled to V4 compressors, so were subject to a fair bit of vibration but never failed in normal use.

Typical material thicknesses were 3 to 6mm from memory, some machines used spool guns while others were standard wire feed due to access difficulties.

Originally Posted by shenion

The corrosion cracking with 5356 is hard to pin down. Many sites just say not to be used at elevated temps. I have seen users that swear by 5356 on repairing aluminum heads and have never seen a problem. I did find one table that implied the temp problem was using 5356 on 6xxx grades.

Stress corrosion cracking, barely scratches the surface of a heavy going subject but that article suggests that even the boffins don't have a complete handle on it yet so we don't stand much of a chance. I guess it's just easier/safer for the manufacturers to not recommend it's use for weldments that'll see sustained service over 65C regardless of other factors.

Cylinder heads... i suppose the nice thing about/reasoning behind using 5356 is more to do with the following machine work. 4043 is a bitch to machine and while there are better matching wires (4145, 2319) for the alloys that cylinder heads are cast from finding 'em ain't easy.