tips for mig welding aluminium

Zedn · #1 (**permalink**) 02-04-2011, 03:45 AM

I have decided that it is time i added aluminium welding to my skills. I spent about half an hour tonight playing around with my mig on 1.6mm and 3mm Al. I managed to get a pretty good result once i figured you need a fast wire speed and move quickly.

Im wondering if anyone is experienced with mig welding aluminium and can give me any pointers for spot welding and also reducing build up at the start of the weld.

When i try to tack the piece in place, the tack is really messy and dirty and doesnt flow. Once i start welding, its perfect after about 20mm, but the first bit is a big clump that doesnt penatrate.

I intend to spend a few hours over the weekend to get the hang of it but thought i would get some pointers first.

Buying an AC tig is not an option.

Modena · #2 (**permalink**) 02-04-2011, 04:20 AM

I watched a short youtube video once of a guy showing how to weld thin car panels, and apparently a similar technique can be used on al. Basically squeeze and release, move ~5mm, squeeze and release, doing this quickly to retain heat, so its really an ongoing overlapping line of spot welds. Comes out in a pretty nice stack of dimes if you do it well. I've only done this on steel, never tried al (yet)

Zedn · #3 (**permalink**) 02-04-2011, 04:32 AM

I think that would make my problem worse because it is the start of the weld that is ugly and then it gets nice as i go.

FWB · #4 (**permalink**) 02-04-2011, 06:47 AM

i have gotten a much nicer bead, cleaner, less poopy, if i heat or warm up the items i'm going to weld either with a flame or oven. AL sucks to mig, move fast, AL is a natural heat sink, it'll get very very hot fast.....

Fred

Jerry Clayton · #5 (**permalink**) 02-04-2011, 07:09 AM

if buying a tig isn't an option , how about trying to trade your mig in on the tig?

Up here places like C & R radiators use a special gun that wiggles the wire---I think they use Lincolns welders

renovationinnov · #6 (**permalink**) 02-04-2011, 09:17 PM

the guy next door migs boats for a living said to try you feeder rollers that there not to tight / loose
then check your liner & check your allyspool for **** [ his words] on the wire try running a rag over it to keep it clean ' , he said to run a old piece of soft carpet on the spool all the time to remove ally corrsion off the wire [ you don,t know how long it has bben on the shelf
hope this helps rob

Zedn · #7 (**permalink**) 02-05-2011, 12:53 AM

Quote:

Originally Posted by renovationinnov

the guy next door migs boats for a living said to try you feeder rollers that there not to tight / loose
then check your liner & check your allyspool for **** [ his words] on the wire try running a rag over it to keep it clean ' , he said to run a old piece of soft carpet on the spool all the time to remove ally corrsion off the wire [ you don,t know how long it has bben on the shelf
hope this helps rob

Thanks Rob,

Il check it out. I spent some time welding today and im really happy with the result. I am just working on scrap at the moment, but after today i think im ready to start on the car. Its still a bit rough for the first 10mm of the run, but i will check the spools not binding up at the start and slowing the feed. Im getting good penatration at least so appearance doesnt matter too much as i will grind it smooth.

Cheers.

Liam

mickmate · #8 (**permalink**) 02-05-2011, 07:43 AM

Get it mechanically clean with a stainless brush and make sure you're getting consistent feed. The two biggest factors I found with MIG on ally was the angle of the feed (15 deg from perpendicular) and I found a brand of wire that really worked better than what I started with. The cleanliness of the wire may have had a lot to do with it also. There's some good tips here http://www.millerwelds.com/resources...cess-at-Home-/
Sounds like you might want it a bit cleaner and hotter to start with then travel a bit slower for more deposition and cooling.

LT65 · #9 (**permalink**) 02-05-2011, 08:15 PM

Use a nylon liner just for the ally. Clean clean clean use a stainless brush only on the ally NOTHING else, the ugly lump is a cold start. Maybe start from the other end LOL.
Perhaps start in from the end to heat the job then come back to the end and go over your cold start , been a while since i've done lots of ally welding but this might help other than a TIG.

Zedn · #10 (**permalink**) 02-05-2011, 08:34 PM

Quote:

Originally Posted by LT65

Use a nylon liner just for the ally. Clean clean clean use a stainless brush only on the ally NOTHING else, the ugly lump is a cold start. Maybe start from the other end LOL.
Perhaps start in from the end to heat the job then come back to the end and go over your cold start , been a while since i've done lots of ally welding but this might help other than a TIG.

Im not sure if that would overheat doing it that way, but i will give it a try. I have found that it is still penetrating and looks ok when its ground. I am going to be covering my footboxes with Al so the welds will be ground flat any way.

Thanks for the advice everyone.

Liam

Wbulk · #11 (**permalink**) 02-05-2011, 08:36 PM

This is the best web site for welding information I have found. I have it set up so I get an email every week when he comes out with a new welding lesson.
http://www.weldingtipsandtricks.com/

jetsbaby · #12 (**permalink**) 02-05-2011, 08:39 PM

I have a Miller 252 mig with the 30A spoolmatic gun...I have great results with the larger wire spool then the .030 and .035 size..The keys to welding aluminum especially thin metal is to cool the puddle down fast which is accomplished with the larger wire..Also use a step and pause technique. All most looks like it when you get it down right..