aluminum welding with mig

[kumma]

Sounds like there are a few more than capable welders on the board. Heres a shot of my first attempt at mig welding aluminum. Took a little while adjusting heat and speed as well as hand position but I think its working pretty well now. Im laying a bead down pretty good with very little splatter. This is on 1/8 x 1 aluminum pieces that are going to be used as a rack for washing out screens. Doesnt need to look pretty just hold up. Any tips or suggestions. Is the bead to large?



I dont know what all the fuss is about with mig and aluminum, I havent run into any problems with feeding or anything else for that matter. Seems like it just takes time to figure it out. Using a Miller 135 with argon and .035 wire.

[cstreit]

i haven't attempted welding alum. with my mig yet. Can you tell me what alloy wire you used?

[John Rogers]

When I started to make a set of long aluminum ramps for getting the race car on the trailer I found my 110v MIG welder was seriously stressed. I sold it and bought a 220V with much more power and it welds great. Aluminum needs a lot more heat and I found that preheating helped some since the heat disapates so quickly. I used the wire and gas recommended by the weld supply shop for 6061T6 and had no issues. I also have a couple of wire brushes that are used only for aluminum since they can pick up iron particles that will contaminate the aluminum welds. Your weld looks pretty dang good I'd say.

[928ram]

I looked into this several years ago when I was going to repair a crack in a 928 fender (in the end I found a replacement fender), the tips I remember from asking were to be sure to get the right alloy for the job (would have been more critical on the thin fender), get a liner designed for alum. (Teflon I think) , alos I think I remember that Alum. welds better with the welders polarity reversed(?).
The reason for the liner was that the alum wire would flow smoother and that the contaminants from steel wire could cause the alum. wire to corrode and get stuck in the liner used for steel wire.

[turbo6bar]

How's the penetration? If you think MIG and Al is easy, try TIG + Al. It's humbling.

[Tim Hancock]

Check the back side to see if you are getting penetration. You will still see the joining line, but it should be melted there and will not be a crack anymore. If an actual crack is still there, you did not penetrate enough, at least when you are welding thin stock. Also try to break your sample, if it breaks right where the original crack is, you did not penetrate well enough. I had to practise alot before I could trust my tig welds on >050 aluminum aircraft fuel tanks. Initially I thought it was fairly easy and my sample welds "looked" awesome, but I soon found that I was not getting full penetration and the welds would easily fail at the joint. On thin stock you should actually see a slight bulge on the backside to be sure you actually penetrated.

All this info should translate to mig welds as far as penetration goes.
Cleanliness is critical and it looks like your sample wall cleaned well. Just make sure you use a dedicated alum only stainless steel wire brush for a final clean right before you weld. It is also desirable to clean your tack weld before finish welding as there will be impurities in the tacks you just laid down.

[qikcpa]

Also, there are some specific metal preps available for welding Al. i found all the above to be true. I even have a seperate gun/liner just for Al.

[surflvr911sc]

That bead is huge imo. Not really your fault, that's what mig makes you do unless you are really good w/ it. A good weld should require little, if any, finish work to look good.

IMO you can't beat TIG. You just about melt the metal (AL, SS, etc) together and only feed when necessary. It may take a little longer to get right w/ different metals but the result is unequaled.

[kumma]

I used ER5356 wire. Heres a picture after I put it in vice and smashed it with a hammer a couple of times. It held up well, the weld didnt crack and it bent on either side of it. Not scientific but im not building an airplane just a small rack. Excuse the poor picture my camera sucks indoors.



As far as penetration, I butted the 2 pieces right up to each other and on the back I can still see the joint. Towards the end of the run its puddled a bit as the heat built up. Its nothing like steel, the joint is still there and there is no heat affected zone to judge by. Should I bevel the joints first or leave a little gap between the pieces?

With all the talk about how its a nightmare to mig aluminum I was not expecting to even be able to lay a bead down at all. So far Im pleased with it. I used a new stainless brush and have a new liner which I didnt replace yet.

I'd love to try a tig machine, just dont have the cash to buy one. I have an aluminum mountain bike which has impressive welds that I just drool over, so a TIG machine is definatly in my future. Im going to take some tig welding classes at the local tech college so I can get to use one before jumping in and buying one. New credit card and wanting new tools makes for a big problem for me.

[Tim Hancock]

If it didn't break you are in good shape. As I stated earlier, with aluminum butt joint welds, you will see the original joint line on the back side, but if you penetrated, it will just be a visible line, but not an actual gap that you could feel with a fingernail or something (think of it as a stain).

For that relatively thin material you do not need to leave a gap or bevel and it is good if you have a little hump showing up on the bottom when welding thin aluminum, if you don't you probably are not getting full penetration. None of this matters if the item you are building is lightly loaded, but when strength is an issue just make sure you fully penetrate.

It looks like you have it figured out plenty good for what you are making.

[RickM]

One of the biggest hurdles with MIGing aluminum is feeding the wire consistently...or at all.

Lendaddy (Joel) has shown some of his MIGed aluminum work and Ohh Man it's a thing of beauty.

Let's get him on this thread for advice.

[lendaddy]

This was already mentioned here, and I can't believe I never brought it up before. Clean!!!!!!!!!!!!!!!!!!!!! aluminum MIG hates contamination. We actually clean all our parts in a vapor degreaser before welding to remove all contamination and oils. You will not believe the difference this makes. I would imagine a home user could get by with brake cleaner or alcohol. This cleaning made the go/no go difference for our process here.

Also, FWIW your bead doesn't look "that" wide to me, but it's hard to get perspective. If you're already that far along you'll be a champ in no time, practice is key. Regarding TIG, you can't beat it for "pretty" and really for uniform strength either. It's simply incredibly slow by comparison and much less handy. Try filling largish gaps with AL TIG, good luck. But with a snug fit TIG is a joy, hell it's fun! Choices choices

Oh yea, Rick mentioned wire feed. This IS a biggie. If you can afford it (not that bad) a spool feeder is golden.

[ErricZ]

Why not try a little mix gas? Al seems to work better with an Argon/CO2 mixture, esp. when MIGing it.

You know you're good when you can TIG to the end of an Aluminum sheet and not melt the thing away in your hands.