MIG welding Aluminium...

[alanganes]

I am looking at a few projects where the ability to weld some aluminum parts would be really useful. These will likely be 6061 square, rectangular and maybe round tubes, welded together or to 6061 plate. Typically would be 1/8" wall tube and similar thickness plate.

I have an older MIG machine, a Lincoln Idealarc SP-200. I have used it mostly only for steel and on a few occasions, stainless. It has always worked great for that sort of thing.

I'm mostly looking for info from folks who have done this. Just wondering how difficult it is to MIG aluminum, and if you think this machine would be up to the task. Curious what sort of settings/filler/gas would work best to get in the ballpark, in your experience.

I've TIG welded aluminum just a few times, though nothing complex. It was a bit of a challenge to get a few passably decent welds. Would it be any "easier" (relative term...) to get OK MIG welds?

Just for the record, this is not "mission critical" stuff, meaning that nobody will be killed or maimed if one of my welds were to fail, nothing will fall from the sky, etc. On the other hand, I would prefer for my welds not to fail...

Just hoping to tap the collective wisdom here.

Thanks,
Al

[airsmith282]

from what i know on the subject you dont mig aluim you tig it or you can use HST rods with a propane tourch also sudotec 78 rod wiht a tourch also works how well not sure oin that , or if oyut mig and use a aluim spool gun like the lincon 140 and 180s do then you can do aluim that way as well..

and yes your machine can hadle it if a 180 can do it then a 200 sure can so long as you can use a spool gun kit of some sort ...

you could try brazing it but i dont know enough about brazing to say if it would works iam kinda new to brazing my self and so far only done steel ,,,

[Ken_Shea]

You can most definitely Mig weld aluminum, takes a different shielding gas then for steel, like argon, I have used years ago some sort of mixed gas for that but do not recall the name, your gas supplier will know.

Ken

[EdC]

From my experience it is possible. You will need to change the liner in the whip to eliminate filler contamination, use straight Argon and 5356 filler...

Now most MIG Machines used for Aluminum have a "pull" type gun with feed rollers in the head as Al can have a tendency to kink and jam in the liner when pushed. So you need the set your feed roller tension to let the wire slip when you pinch it with your fingers at the contact tip to avoid a backlash if ti does burn back to the tip or get jammed.

I prefer a Spool Gun set up personally.

[Deja Vu]

one extra litle note for the liner...after replacing and ready to "experiment"(in your case), try to position your work so the liner/feed allows as straight a run conveniently so the wire passes through with as little friction as possible.

[seattle smitty]

The usual way to weld aluminum with a MIG power supply is to hook up a spool gun, or with a "pull" gun like a Cobramatic. The trouble with trying to push aluminum wire through a MIG cable/gun is that the wire is so soft and the drag of the cable is so great that the wire wants to wad itself up into a "bird nest" between the drive roller and the cable. However, with care you may be able to make it work:



Go to the welding supply store and buy a Teflon liner for your cable. Keep it for use only with aluminum wire.

Make sure you have a knurled drive roller.

Don't try to use aluminum wire smaller than .035"

Use a .045" contact tip with .035" aluminum wire, or drill out an old smaller tip several thousandths over .035".

Use straight argon gas. You can rent a bottle.

Make sure you get the right alloy wire for the job. This won't affect the feeding of the wire, but it sure will affect the weld.

When you set up to do the job, you want the cable to be stretched out as straight as possible. Drape it over the backs of chairs or whatever to have a straight run (therefore, low drag on the wire) from power supply to gun. Keep re-positioning the work as necessary to keep the gun and cable lined up.


Good luck. This is done, and you can probably do it. However, if you plan on doing a fair amount of aluminum, you may want to come up with a new or used spool gun (pull-guns like the Cobramatic are expensive). Spool guns feel kind of clunky at first, but they work at any angle and you don't have to worry about keeping the cable straight. If your welder wasn't designed specifically to take a spool gun, you'll need an intermediate control box. Go to the Lincoln site, and they'll tell you all about it.

People will tell you that you really should have a TIG machine to do aluminum, but you can do lots of jobs with a spool gun and the machine you have; aluminum boats are all welded with spool guns because they lay down a bead far faster than TIG. Also, don't forget that some aluminum welding jobs can be done with a gas welding outfit, if you are a contrarian and like to learn unusual skills.

[derekm]

I'd make sure you have plenty of practice materials to hand...Argon is the Gas, wire is thicker and It takes a swift and steady hand to make it work. That said, you can get some beautiful results (very TIG like). but it takes a more "art" than welding steel with a MIG. I didnt find any problems getting a strong weld more the opposite of it all melting (high conductivity of the Al), hence the "swift hand" and didnt have any probs with wire jamming IROC.

[bob308]

i pushed .060 al wire through 8' leads for years. we welded mil spec. 1 1/4". thick al. plate. the leads needed to be water cooled, the guns were stright. they did not have the curve of a steel gun.

[Tinkerer]

I've done quite a bit of Alum welding from sign cabinets to awnings. Argon is the gas you'll need. The teflon liner is a must. I've pushed .30 thru a ten foot whip with no trouble on a older SP-100 just had to pay attention and not coil it but .35 is easier yet. Clean the drive wheel groves when adjusting the tension I had it just tight enough that it would not slip when pushing on the wire. Place a felt wipe after the wheel I use a polishing disk for the dermel tool just cut a slit in it. Get a new stainless wire brush to knock the oxide off from the weld area then get right to it if you wait as much as five minutes re wheel it. Also a SS small hand brush is handy. Your SP-200 should do fine on 1/8" stock just take some scrap and play a little... Oh when you have the welder set right it will sound like bacon cooking when you weld. Welding Alum is not as big a challenge as most think it is and some what you to believe... you can do it.

[alanganes]

Thanks very much for the replies. Lots of good info here, I really appreciate it. I have a new, second gun and cable that came with the machine, maybe I'll outfit that one with the teflon liner and keep it set up just for aluminum work.

Another question or two, if I may. Any recommendation on wire? I happen to have a small spool of ER5356 filler (0.030, I think). I'm not worried about buying a spool of a different filler, if that would work better or run more easily. Again, this is for 6061, 1/8" thick.

This all got me thinking, why is it that one can MIG aluminum with DC, but TIG requires AC? Or does it? Just curious.

I'll be getting all this stuff together over the next few weeks, once I give this a try, I'm sure I'll have lots more questions. It is great to get this info first hand from guys who have actually done it.

Thanks again.

-Al

[EdC]

.030" 5356 should be fine.

[alanganes]

EdC, thanks for that. Now that I looked back, you did mention that filler already.

If I find I can actually get to the point where I am able to generate decent welds, I may hunt around for a spool gun. For the time being, my lead is not exceptionally long now and I will be working on small-ish stuff. So I'll easily be able to position the work and the machine such that my lead is straight and smooth.

Appreciate the reply.

-Al

[alanganes]

So I went out to the shed to retieve my new-in-the-box spare Tweco MIG gun. A bit dusty, but all there and unused. When I look inside the box, Bonus!, there in the box is another smaller box. It says right on it "Teflon conduit for 0.035 aluminum or stainless filler wire"! How cool is that? Neat-O, I guess I don't need to buy one of those now.

My question(s):
Is this ONLY good for 0.035 wire? I have a small spool of 0.030, could I use that with this liner, or is it better if they match? Another small spool of larger wire will not bother me, if it would work better.

In perusing the Lincoln website, it mentions that one should NOT use a knurled drive roller, but one with a "U" shaped groove rather than a "V" groove. That seems contradictory to what Smitty said in his very helpful and detailed reply. Am I misunderstanding one or the other?

Thanks for the input, guys.

-Al

[Tinkerer]

Al... that's cool you can use that liner up to .35 that is the same liner I have should have a orange color code on it I and used .23 and .30 in it. I just used the wheels that came with it more of a channel then a U but you can use the U drive wheels if you have them as for the knurled wheels they can chew up the surface causing more drag.

[JND]

Try the smooth,or U shaped rolls first,if they slip then switch to the knureld roller.Sometimes the knurled rolls are nesecary,eventhough they chew up the liner faster.You'll notice that black burn area around the weld,thats what there talking about brushing off QUICKLY while warm it's alot easier.If you crank the heat and speed up, after some practice you can get the weld clean and flatter,play with the angle of the gun to achive this.When you weld start at the thinist area,and move towards the web,or thicker area as the heat builds,it makes a nicer weld.
Nick.
P.S.Put everything else on the table up,and make sure you ventilated,there will be alot of grey smoke,and splatter.Especialy while learning.:D

[10KPete]

It looks like you have all the correct info for your foray into MIGing aluminum. The only thing that's still a bit unclear is about the feed rolls maybe. Use smooth groove rolls, correct size for the wire, you shouldn't need anything with more grip. Don't tighten the rolls any more than necessary to reliably push the wire or you'll have wireballs every time the arc stutters.

Another thing that really helps, and not just with aluminum, is to put a lubricating wiper on the wire between the feed rolls and where the wire enters the liner. This is simply a little felt pad and a binder clip (one of those blue steel paper clip things with two folding handles) that 'pinches' the wire. Dampen the pad with some Marvel Mystery Oil; don't need much. This will dramatically cut the wire friction in the liner and really improve contact tip life. And no, you won't notice any more smoke. :D

One pound guns or Cobra-Matics are THE way to go!!




This all got me thinking, why is it that one can MIG aluminum with DC, but TIG requires AC? Or does it? Just curious.


DC TIG is great for aluminum but is best used on heavier sections. A 2% Thoriated tungsten and pure helium with 4043 filler is the formula. Single pass 1/2" deep welds are simply great.

Pete

[seattle smitty]

Most aluminum TIG welding is done with AC because the reversing polarity helps break up the surface oxide layer that forms on aluminum even right after you've energetically wire-brushed it. Aluminum is welded by other methods when production rates are more important, as in boat-building. And, as Pete tells us, for TIG welding heavy sections, which I have never done and will take his word on.

[QUOTE=10KPete]
One pound guns or Cobra-Matics are THE way to go!!

I don't use my spool gun enough to like it; it still is a heavy, clumsy, clunky thing (I feel the same way about those Dillon/Heinrob gas torches). But I got to try a new pulsing MIG machine with a Cobramatic-style torch on aluminum, oh lordy, that was an erotic experience! If I were ever going to build myself an aluminum boat, I'd buy one of those machines in a jiffy!

[alanganes]

Again guys, thanks for all of the great info. I spoke with a local welding supply place today, that have a pretty good deal for the gas, so I will likely be getting an tank of Ar next week sometime. I know I have some other feed rollers around here, I've never looked too closely at them, as I have always used the same big spool of filler that came with the machine. Have to dig them out and see what I have. Been gathering up scraps of 6160 to practice on, as well.

Then I expect I'll be back here with more questions to find out what I'm doing wrong...

Thanks again for all of this great info. You guys have probably saved me from many wasted hours of screwing around. It's nice to have a decent starting point.

-Al

[10KPete]

Most aluminum TIG welding is done with AC because the reversing polarity helps break up the surface oxide layer that forms on aluminum even right after you've energetically wire-brushed it.
That's exactly correct. AC is 'self cleaning' because the current reverses for half of the AC sine wave cycle and 'pulls' the oxides off the weld puddle.

However, for the same reason only about half of the current is putting heat into the weld! Most of the new units allow one to shift the zero line of the sine wave thus shifting how much current goes into the weld. And, like the Synchro-Waves did way back, the sine wave can be 'squared up' so more energy is going into the weld also. Think about the 'area under the curve'. The square wave has more energy than the pure sine wave.

The other 'problem' with AC is arc instability. It wants to wander all over the place. That's why the high frequency units came in, to allow the arc to 're-strike' when the AC current cycle crosses the zero line. But AC at very low currents can be quite problematic and joint design is the ruling factor there.


Aluminum is welded by other methods when production rates are more important, as in boat-building. And, as Pete tells us, for TIG welding heavy sections, which I have never done and will take his word on.

The problem with DC is that everything must start out very clean. The rod must be kept inside the shielding gas, the back side of the joint needs to be very tight (or back gassed) to keep oxide formations from being 'sucked' into the back of the deposit. But it's not really that hard and is actually great fun because you can do a lot more weld with much less effort than with AC. A butt joint in 1/4" plate shouldn't be beyond the average guy and anything thicker is cake. With practice one can achieve excellent welds down to 1/8" thick plate provided attention is paid to the joint design.

The other thing to point out is that the filler alloy is picky with DC. For example, when welding 6061 the filler needs to be 4043. 5356 filler yields a very 'dirty' deposit internally. This is a problem because 4043 doesn't give a color matched weld for anodizing!

I have done heavy welds where the base passes were made with DC 4043 and the top passes with AC 5356. The DC passes went a long way to heating up the mass enough that AC could be used for the top passes. Even then, the AC was done with a Syncro-Wave 350 and the wave shift cranked all the way over. But it made it and passed all the x-ray and section testing. Whew!


I don't use my spool gun enough to like it; it still is a heavy, clumsy, clunky thing (I feel the same way about those Dillon/Heinrob gas torches).

Ah, you'll get used to it. It just becomes an extension of yer fist. But I do like the Cobra heads waaaayyyy better.


But I got to try a new pulsing MIG machine with a Cobramatic-style torch on aluminum, oh lordy, that was an erotic experience! If I were ever going to build myself an aluminum boat, I'd buy one of those machines in a jiffy!
Man, aren't those the cats meow!! Talk about heat control! I swear a guy could weld pie tins together if he had enough practice.

In my dreams someday..........

Just remember, a welder has a big advantage over a cabinet maker when it comes to filling up 'mistakes' .....
















those mahogany electrodes are hard to come by!

Have fun!
Pete

[bobhdus]

The thing to mention about the "U" groove rollers is that they will reduce the amount of dancing that the wire will do when it comes out of the tip. Some of the other rollers may work fine but depending on tension to get through without slip or birdnest they can distort the wires cast/helix. Something that you may or may not notice is the first weld on a part is usually the worst one. As the Aluminum gets wamer they smooth out. Sometimes I preheat but its not necessary depending on the process used. I am using Pulse GMAW at work now and with it I can adjust arc length and arc cone. But not affordable for my home shop welding budget. If I do aluminum at home I use oxyacetylene HTS2000 or Ney380. Have fun!

[wmgeorge]

This all got me thinking, why is it that one can MIG aluminum with DC, but TIG requires AC? Or does it? Just curious.

Thanks again.

-Al

TIG DC for aluminum, good question. I saw that discussed somewhere can't remember where right now, but it can be done. One reason for the AC is it cleans the base metal when welding. Maybe someone else will jump in here with the correct procedure. My TIG setup now is Miller Maxstar inverter with DC only.