Welding aluminum

[JRSutton]

I'm good enough with a stick welder or mig welder to make my own general repairs, but far from an "expert".

Have a friend with an aluminum trailer that has some stress cracks in a non-critical area. He was asking if I could weld them.

I said no since it's aluminum - but it did get me thinking.

Aside from tig (I'm couldn't possibly justify new equipment) - just how hard IS it to weld aluminum?

I've never done it, never seen it done, don't know anybody who does it.

Just never had the need. So I've never even looked into it.

CAN you even do it with a mig welder?

Must be very easy to blow through the material, no?
 

[guido]

Hello JRSutton,
Aluminum can be welded with a MIG. If you have run a MIG with steel it may not be hard to learn for you. Cost of equipment is the issue.
If it is not a critical area, can you plated instead? Drill a hole at the end of the cracks first. It will prevent further cracking.
Guido.
 

[thebigyellowtruck]

depending on the thickness of the aluminum you can stick weld it too. I stick welded my 1/8" thick aluminum loading ramps without an issue.
 

[bjb in TX from Ne]

If they are truly "stress cracks" then the area may actually be "critical"...
 

[Puddles]

In most cases you can get by with the average Mig welder. You'll need U-groove drive rolls for the size aluminum wire you want to run. And a nylon liner in your Mig gun. Shorter the gun the better. And if you can do it, place the feeder above the work. Let gravity help you. If by chance your Mig welder will accept a spool gun that would be the way to go, or a push pull gun. You will need 100% argon gas.
To help things out, preheat the first couple inches of the weld zone. See how these two welds are cold for the first couple inches? (Right side).




 

[Puddles]

Few months ago I played around with some aluminum SMAW. Haven't done this since the early 1980s. Now I remember why I didn't like it.



 

[Puddles]

I would much rather Tig weld aluminum.


 

[the tractor vet]

Now i am by no means and expert on this welding Alu. thing as i was forced into it out of need from owning a dump trailer . What i have learned is (1) you need more heat (amp) it must be clean and when you think it is clean clean some more .(2) you push the weld not pull. Next if the Alu. is stress cracking then the metal is done for.
 

[wisbaker]

If you have MIG it isn't that much to go TIG. As for welding Aluminum it is a lot easier than we believe as far as skills go BUT you need knowledge to know what the heck you're doing. I am not a welder and all my aluminum welding experience was during work shops at the EAA convention, If you know what you're doing as far a set up I find it easier than steel. As far a thinness at EAA we saw guys welding pop cans together. After a 1/2 hour instruction they had my 14 y.o. daughter pushing a 3/8" wide bead across two 1/8" thick aluminum plates she was welding together with an Oxy-acetylene torch. The instructor said the last time he saw a bead like that was on a 1930's coach built aluminum Rolls Royce body.
 

[sd pete]

My son tig welds it and he does it for a living. I know nothing about it. His welding has to pass a ridgid inspection. Thats all I know.
 

[Stick welding]

MIG and TIG are entirely different and require different machines. How can "stress cracks" not be critical? In a classroom with a qualified instructor and the proper machine set up, it's a lot easier than doing it on your own with marginal equipment. Aluminum is tricky to learn. It does not turn red hot. It gets shiny and next you know, you have a big hole. It might save you a lot of grief to have someone experienced with aluminum weld it for you.
 

[Bernie/MA]

I've welded aluminum for 40 years. Trailers are built out of 5000 series aluminum so you have to use 5000 series wire in your MIG, like 5356. If you don't the welds will crack. Found out the hard way, had to do a whole job over.
 

[JOB]

Today's mig welder on aluminum works better when you preheat the area to be welded. What I have done is make an acetylene only flame and blacken the area with soot, then open the oxygen and make a neutral flame. Heat the blackened area till the soot is gone, then weld it. The above method works good for tig also.

For tig you need to preheat the area with a torch or else use your tig torch to preheat some. Watch the weld area as it turns fluid and add some filler rod and weld as if you were gas welding. There is a little in technique involved that was not mentioned. I had a female apprentice that was tig welding after I gave her a couple of demos. I have never seen aluminum get hot and make a big hole right away. The weldor would have had to have done something way wrong.

I had the chance to learn oxygen/acetylene welding aluminum many years ago but we had a Tig machine so I passed it up, big mistake.
 

[Stick welding]

I never said aluminum would make a big hole right away. I said it doesn't get red hot and you can end up with a hole if you don't know what to look for. If you have the right machine for the thickness you're doing, you shouldn't need to preheat unless it's a thick section. Most TIG welders use a foot pedal so they can up the amps at the start and then adjust down and up where necessary.
 

[jon f mn]

Where do you live? If you are near enough I would do it for you. You can run al. wire through a reg mig gun but it sucks. You need 100% argon gas to do it and it works better with harder wire like 5356. As said either a push/pull gun or spool gun works best because the wire is so soft it is hard to get it to feed. You can use stick too, but again it's tuff, especially on thin stuff. You are better off to find someone who has the right equipment and get it done right. The proper equipment is faily expensive partially because it takes more power for aluminum because the heat spreads and disapates so fast. On my miller with the spoolgun I almost never use high range for steel but almost never use low range for aluminum.