Mig welding aluminium

[Gary Fowler]

I would forget about trying to weld that thin wall tubing. It would be pretty hard to weld that with a high frequency TIG rig and a professional aluminum welder. Try the propane brazing wire. I saw a demo on that where the guy welded up a 1/2" diameter hole in coke can and it is stronger than the parent metal also. I dont know if it was the same stuff as the link because I couldnt get it to work. I got price for the brazing wire a while back and it was like $40 per pound but a pound would do a lot of work on that tubing. Search you tube for a video of the newest aluminum brazing video.

 

[Stimw]

I have always used Acetone for cleaning. It dries completely and leaves no residue. Just be careful because it is extremely flameable!!
At a previous job I spent 8 hour shifts welding 4' X 12' X 1/4" aluminum panels bent in U shape relining the floors in 38' Aluminum dump semi trailers that had worn through from gravel hauling. I used a spool gun.
First problem is cleaning, second problem is blocking all wind or even air movement. Both are critical.
You are probably also having problems with feeding, aluminum dosen't push well for any distance. The wire can also be dirty or have oxidation on it.

 

[wired1101]

Another issue could be binding in the tip. The wire expands at a faster rate and to a greater degree that steel wire. This causes the variation in feed rate and the bunching you get. I use an oversize tip when welding aliminium and try to keep the liner as straight as possible.

 

[woodsmith]

Thanks for all the advice.

I have possibly bitten off more then I can chew with this and the brazing rod method may well be the sensible option.

It does seem to be a very 'all or nothing' process and very difficult to get anything consistent. It means I can't risk it on a job as getting it wrong ruins the whole project.

The wire is 0.8mm and the tip is 1.2mm I can switch to 1.5mm but I was finding that I was getting the wire melting at the threaded end of the tip.

I shall try some DuraWeld rods, I think they are similar to the Alumiweld stuff but I can get a starter pack of the DuraWeld rod on Ebay uk.

I guess I should put my welder back to steel welding and hope I haven't messed it up. Changing to a teflon liner seems to have lead to gas leaks and a faulty solenoid valve that won't shut off. I have probably lost most of my mini bottle of Argon now so can't really do much more with it.

Guess I'll use the wire for baling drinks cans!

 

[tcartwri]

I have seen some guys do a beautiful job gas welding Al. Something to consider.

 

[rhett]

Hi, to help stop the wire from 'birdnesting - fouling' use the next size larger gun tip. It really does help, if you notice the wire expands and binds in the tip stopping the wire feed resulting in a mess at the rollers. I actually use a Oxy/Acet tip cleaner to slightly enlarge the tip diameter.

 

[swines]

I have welded aluminum with my MIG and then with a TIG. No contest in weld ease and final weld product - TIG because of the AC cleaning action and heat control. What everyone else has said - and then I'm going to add one more. Increase the flow rate of the argon. The blackened welds are most likely because you've lost the shield, and you're incorporating carbon from the carbon dioxide in the air. If not from that - then the aluminum was not cleaned properly. But, even with a TIG, I use a larger cup and a little more gas flow for aluminum.

1. Clean the weld surfaces with acetone before you brush them. This will get contamination off of the metal and you won't brush it into the metal surface.
2. Brush with a stainless brush dedicated for aluminum.
3. Wipe the surface again with acetone using a clean paper towel.
4. Weld immediately after cleaning.
5. Increase the flow rate on the argon.

 

[yomax4]

By looking at your pic's..You are not that far off. Like stated above, You need to learn on thicker material 1/8 or so. Keep the gun straight, tension only as tight as needed and practice. Your welds look like most 1st attempts. You will likely never be able to do a perfect job and that's why they make Tig units, Spool Guns, Push Pull and Twin Pulse Synergic options..

 

[Hooked_on_HP]

You didn't say what wire you were using. If you are trying 4043 give up. It is to soft to push through a liner and if you tighten up the rollers it will flatten it causing more problens at the tip.. You need 5356 wire. This is a stiffer wire.You have to run the 5356 a little hotter than the 4043. I still don't think you will have sucess welding tubing that thin. But you will be able to weld thicker aluminum if you ever need to. About the only way to mig weld somthing that thin is with a pulse machine. Even with my spool gun I can only do a good job of welding material .080 or thicker.
Bill

 

[Shield Arc]

I didn't read every word in this thread, so forgive me if this has already been mentioned!
I sort of remember trying to do this years ago, (30) before buying my first Tig welder. I had a Miller S32S remote wire feeder that I ran on my 450-amp diesel drive. I bought the shortest Mig gun I could get, with a nylon liner, U-groove drive rolls for the feeder, and hung the feeder above the work, so gravity could help me. Had to keep the Mig gun as straight as possible at all times, or I'd spend the next 5-minutes cutting the bird's nest out of the drive rolls. It can be done, but what a PITA!

Here is a couple pictures of a 1/16th inch corner joint I did when I first got my spool gun. I'd still rather use Tig! I never have been comfortable welding thin material, even to this day 3/8 inch is about my limit!