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MIG welding Aluminum

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Lucrum

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I did mig welding on aluminum for some time back in the 1980s. A 120V welder is useless for that. The polarity is reversed, as others have pointed out, and I also had much better welding when I used a helium/argon mix. I ended up using two bottles (one argon, the other helium) and two flowmeters, teed to the welder's gas line, and adjusted the flows to what worked the best for the castings we were welding. Helium brings the heat up a lot and you can use less amperage.

Teflon liner, rubber roller so that the aluminum doesn't get deformed by the rollers. No preheating at all.

We also welded a lot of cast iron using nickel wire. Lots more hassle than aluminum. The best aluminum guys are those that have never welded steel. No habits to unlearn. Aluminum has a very narrow plastic state temperature band and steel welders can get frustrated by its sudden melting away into a puddle.

Oxyacetylene welding aluminum is a futile pursuit.

Dan
Interesting, thanks. I have a 240V MIG with reversible polarity. But no bottles for gas and as such haven't even attempted aluminum yet.
 

4trade

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You certainly need good welds for this but it's not impossible to do that with a small welder. My Mig is only 120A and I have easily welded billets weighing around 5kg/12lb. You definitely need to do test pieces and if you're not able to sustain a good puddle then increase the preheat temperature until you can.
You need to preheat that part almost melting point to weld it that low amps. 120 amps don´t have enough penetration to weld it like it should weld....we are talking airworthy parts here.
 

Head in the clouds

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You need to preheat that part almost melting point to weld it that low amps. 120 amps don´t have enough penetration to weld it like it should weld....we are talking airworthy parts here.
As you like... I have done it, regularly, as a matter of course. It does require some understanding of the variables. Fine wire is a must. An exceptionally high wire feedrate is another. I wasn't saying it is easy but its not that difficult either. Not so many years ago I employed 4 full-time aly welders in my shop so I have a rough idea of what I'm talking about, with respect.
 

4trade

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I have literally few miles of aluminum welding seam experience, and MIG welding examination/class? (don´t know proper English word) with x-ray examination for aluminum welding. My advise for this guy is pure practical/ safe depending what i know for this discussion. It can be done, but it need preheat, experience and proper welding machine.

He got 120 amp, cheap basic MIG. That welding machine produce 120 amp only for spot weld, but constant welding arc amps is closer 80 amps true. Spot welding is out of question for this kind of aluminum welding. This kind of welding machine is really too weak for that kind of job. Lack of experience and welding machine that don´t fit is wast of time and money for him.

200 amps welding machine do that job much better (with preheat) because it will keep 120 amps arc constantly, but his machine will drop amps somewhere 80-90 constant. It will weld cold run seam and that is not airworthy part.

Cheers
Vesa
 

Sir Joab

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Well, I've gone and tried all of these suggestions and no success... I got out the old Oxy-Acetylene torch and was able to weld a couple of pieces together... but it's far too unwieldy in my hands. I always blow through the tube walls...

So now I've been looking at TIG welders. I found one that fits my budget. It's AC or DC (switchable), has the foot pedal control, "high-frequency start", and can output a maximum of 200 Amps. Does this thing look like it would do the job? I'd love to have a TIG welder anyway, but it needs to be able to weld those heads.

The welder: TIG Welder - Eastwood AC/DC TIG Welder | TIG Welding | TIG Welders

--Joe
 

Head in the clouds

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Well, I've gone and tried all of these suggestions and no success... I got out the old Oxy-Acetylene torch and was able to weld a couple of pieces together... but it's far too unwieldy in my hands. I always blow through the tube walls...

So now I've been looking at TIG welders. I found one that fits my budget. It's AC or DC (switchable), has the foot pedal control, "high-frequency start", and can output a maximum of 200 Amps. Does this thing look like it would do the job? I'd love to have a TIG welder anyway, but it needs to be able to weld those heads.

The welder: TIG Welder - Eastwood AC/DC TIG Welder | TIG Welding | TIG Welders

--Joe
A 200 amp machine should do the job fairly easily - with sufficient preheat - but I'm a bit concerned about this Eastwood one. I have a modern 200 amp inverter TIG which is much smaller than the old induction (transformer) variety but mine is way bigger than this Eastwood one. I know they do ever more clever things with electronics and this Eastwood one has a low duty cycle but even so... some manufacturers are not always entirely honest about the performance of their products - a bit like plane manufacturers you know?

I can't read the labels on the controls of this TIG either but it seems to have very few adjustables, the most useful for aly are AC freq control useful for arc focus but not essential (cycles/sec (Hz) pref 20-200Hz), pulse freq useful (0.5-100Hz), pulse duty (10-90%) AC balance essential (cleaning width - 20-80%).

Mine claims welding of 12mm aly (cold) that one claims 1/4" which is only half that...

Mine has a 60% duty cycle at 200A (theirs is 45% at 160A) so that may account for the difference in size and you would not need a high duty cycle for home use.

Their price is very good if it is US made, mine is chinese and has AC, DC, MMA and is also a plasma cutter and cost the same, most chinese stuff here is way cheaper than US goods.

Since they know their product I would ask them whether it will do the job you want to do, then if it won't you have reason to return it. Keep in mind that your job is probably one of the highest demands you will require of it.
 

dino

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A plain buzz box welder attached to a TIG torch can be made to work for welding aluminum. By no means ideal but do able.

Dino
 

SVSUSteve

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A plain buzz box welder attached to a TIG torch can be made to work for welding aluminum. By no means ideal but do able.

Dino
The question though is "Can it be made to work in such a way that a rational and sane person would be willing to bet their life upon it?".

I freely admit that I'm still very much an amateur when it comes to welding and I'm still learning so this is a serious question and not an attempt at a thread derail.

most chinese stuff here is way cheaper than US goods.
Just like in the US!
 

dino

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If your life depends on it and you don't like the idea idea of experimenting take the advice of others and have it done by a certified welder.

Dino
 

Sir Joab

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If your life depends on it and you don't like the idea idea of experimenting take the advice of others and have it done by a certified welder.

Dino
It's an intake port on each head... The mechanical stress is about as minimal as it gets. I'd use JB weld if I thought it would take the heat and vibration. :ponder:
 

dino

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The intake risers I welded up for my Subaru were welded by a certified welder in 8 minutes using TIG and cost 30 bucks. Outsourcing a small job like this lets you get experience by watching as the weld is being done.

Dino
 

SVSUSteve

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If your life depends on it and you don't like the idea idea of experimenting take the advice of others and have it done by a certified welder
I don't mind learning to do it myself because I don't think it needs to be quite the level of a weld coming out of the Electric Boat Company. The question was is that particular technique able to be made "to work" sufficient that it's comparable to other techniques in the hands of someone with comparable skills in each.

Granted, I'll never be welding on an engine (because I see no need for it) but my interest is in the application of the various techniques for other parts of the aircraft.
 
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