Welding Aluminum, Need help

[Chuck Moreland]

I'm making a first attempt at welding aluminum with my MIG. I've got basic skills welding steel, but this is a different animal.

The filler and base are not fusing, not at all. It just clumps up in the tip, quickly clogging it. I tried increasing the stick-out, to no effect.

The base metal is just getting burnt, turning ashen.

I'm using 100% argon, .030 wire and a low amperage 110 machine.

When I bought the AL wire, the guys at the shop warned me I was in for problems. They were right.

Any tips on how to do this? I know, use a TIG. But anyway to do this with my MIG?

[911nut]

Clean any lubricants or oils with a degreaser. Next, remove oxides by chemically etching or wire brushing. Aluminum oxide is a refractory and will cause lack of wetting. Use direct current reverse polarity (electrode positive).

[addictionMS]

I have been told that the steel wire you have been using has some oil on it and to do Al welding, you really need to have a dedictaed wire feed tube.

Jim

[Rot 911]

Read this: http://www.lincolnelectric.com/knowledge/articles/content/compactmig.asp

[qikcpa]

i had a little bit of luck welding al with a mig. i had to swap out the gun/torch as well as the cable. from what i could gather even the slightest dust particle of steel on the al wire would cause a big mess. used etcher and a new wire brush (again to avoid steel contamination). you could check miller.com and lincoln electric's site for faq and forums. I think that was where i got most of my info to do it.

[widebody911]

What I did was buy a new 'wand' for doing aluminum, with a teflon liner. It only takes 10-15 minutes to swap from my Fe setup to my Al setup. I've only done a little bit of Al welding, but I did buy a welding book, and one thing I learned from the book was you have to 'push' the weld, rather than pull like you do with steel. This pre-heats the base material and allows better penetration. It works; when I 'pull' it globs, when I 'push' it sinks in.

It will also help, with this setup, to have the cable as straight as possible. Any friction at all will cause the wire to build a nice bird's nest at the roller. I also use a .035 tip with .030 Al wire.

The book was $10 @ the welding store, and while it was targeted toward professional welders, I think it was till money well spent.

[unclebilly]

Wire feed with aluminum always turns the weld and surrounding metal black, you need to clean it up later with a dedicated stainless steel wire brush (if you use on that's been used for steel, you'll drive steel into the aluminum and it will look rusty).

I'd say you're doing things right.

[TerryH]

It's been years but if I remember we used to preheat the aluminum and use helium instead of argon.

[P Clingman]

I weld alum every day with the mig using a spool gun and the welds come out as good as a tig just much faster. For heavy plate you need
to preheat to get good penetration I run 030 5086 at about 120 amps DC
with the spoolgun + and about 30 to 40 cfh strait argon. It sounds like you have no gas or wrong gas or wrong polarity or the machine is on AC. Palmer

[billyboy]

I would concur with Palmer and say the symptoms sound like no gas or too low a flow of gas. Also welding in a breezy spot will blow the gas away.

[billyboy]

one other thing, tip clogging when everything else is right, is caused by too low a wire feed speed for the amperage.

[KCPSG]

I also agree w/ P Clingman
you need a spool gun to weld aluminum.....aluminum is too soft to travel through the liner of your regular set up. and when you try to tighten up on the wire feed it just deforms the wire. also increase the gas pressure a little if you are outside.

[Chuck Moreland]

Good input, all.

I'll have another go today. I'll turn up the gas pressure, clean the metal better, speed the feed, and push instead of pull.

Sounds like I've done just about everything wrong

At least I'm having no problems getting the wire to feed.

Thanks for the excellent feedback so far. The breadth of knowledge / experience on this board continues to amaze.

[Oldporsche]

I know that I was taught to run Aluminum with AC and TIG. I have never used a MIG unit to do so.

A little preheat will help of the material is very thick.

David Duffield

[84toy]

Chuck, these guys have given you good advice. I have both TIG and MIG and I never use the MIG to do fine work. It's really designed for fabrication work. One more tid-bit of advice..... After each weld, snip the end of the wire off to get the proper length and fresh wire. This helps the start. Pre heat a big benefit, clean a must and if it is a used oil retaining piece, I would put it in the oven and cook out the impurities before welding. Good luck.....

[dfink]

Make sure that you have the surfaces perfectly clean. Any contamination on the aluminum will cause the clumping you describe the comtaminates float to surface and the aluminum dumps out the bottom. Get a stainless steel brush [Not regular wire] to clean the surfaces with and never use it to clean anything else. I found the stainless brush to be the best at getting a good weld. This was with TIG and not MIG. I think we also used a different flow rate for the argon when welding aluminum. Been a while since I welded much but so I hope this helps a little.

[valenciacarrera]

Make sure you pre-heat the items to be welded around 250F and just before you weld make sure the surface to be cleaned with a clean wire brush or carbid knief. There are many ways to weld aluminum for different application. MIG or TIG can be used with combination of AC or DC. I prefer AC just because it has a self cleaning property. However, the draw back is not enough heat input if you are welding a thick piece. Also, it is important to know the class of aluminum for the given application. For instance, for a 6061 T6 material, it needs to be heat treated and stress relief. One last thing, make sure you store the welding wires in a dry and clean environment. The contaminants in welding wire will definitely cause a porisity in the weld. Porisity can be a pain since you can not see it from the surface.

[billyboy]

After you clean the aluminum for welding, you can put a little carbon soot from your acetylene torch burning with out oxygen, near the area to be welded. Then preheat with the rosebud on the oxy/acetylene. When the black of the soot goes away, you are just below the melting point of the aluminum and it's time to weld.

[lendaddy]

I don't know exactly what you're trying to weld, but 110V welders have several disadvantages. That being said I'm sure it can be done even with those "lil" welders . You do NOT need to preheat the AL, but cleanliness is king. Also, it will take you a while to get use to the way it looks when it's flowing compared to steel. There is no color change so you really have to pay attention. A little oxidation (the black soot) on the sides of the weld is normal, just clean it when you're done.

For cleaning, I would use brake cleaner.

Thom is right about another setup(gun/liner) for AL, and the teflon liner is also a great idea. As mentioned, a spool gun will give you your best results, depending on your current setup it could be the difference between night and day.

One observation I made was that the AL was flowing/penetrating almost immediately. After years of running steel you get it in your head that the puddle will be obvious, but with AL it's not. I think this is why most prefer TIG on AL, because the puddle "shows" more, those that have done both know what I mean.
MIG on aluminum sucks monkey ass until you "get it" then you'll love it. Good luck.

[lendaddy]

Another thing, with AL MIG, the rule is:

When in doubt....give it the juice! You can run real hot on AL. You will actually reach the point where the wire is molten before it even gets to the substrate. This is called spray transfer, and it is fantastic Bring the love, bring the heat.