I spent some time practicing MIG welding aluminum today. It’s a difficult skill to master.
I spent a lot of time reading articles and tutorials all over the web about MIG welding aluminum. Some of the articles helped, some simply confused me. Most people recommend using 4043 .035″ MIG wire for general purpose aluminum welding. That didn’t work for me.
I tried working with the 4043 for about 30 minutes. It wouldn’t feed through the gun properly even with a brand new Teflon liner. When I could get it to feed for long enough to attempt to weld I’d just burn holes through the 5000 series 1″ aluminum tubing I’m using even at the lowest voltage setting on the welder. It was pretty frustrating.
I was ready to give up and wait for the spool gun to arrive early next week. I do have one roll of .030″ 5356 aluminum welding wire so I figured I’d give it a shot. I’m glad I did. I can learn to weld with this wire. Using the .030″ with a .035″ tip works perfectly on my Hobart Beta-Mig 170 welder. I’m kinda surprised how fast I have to run the wire speed setting. I guess that’s normal and I shouldn’t be surprised. I just need to order more wire so I don’t run out.
I finally got to the point that I felt comfortable enough that I could do simple tack welds so I could start assembling the base tray of the roof rack. It was right around then that my left eye started swelling. I guess I didn’t get the welding hood down the whole way and a bit of arc flash got me. It was bad enough that I knew I should stop welding and get out of the sun. It scared the crap out of me. I decided it was time to upgrade my welding helmet to one of the auto-darkening types. They sell them at Jordan Lumber so I picked one up. Wow, what an improvement. I can see what I’m doing and it doesn’t hurt my eyes!
Check out the photo gallery below for examples of what aluminum welds should not look like. It’s an random selection of the learning process today before the eye pain started.
Hey, Rufus.
Welding tubes like this is not an easy skill under the best circumstances. Just to give you some background I’ve been welding for more than 10 years, and now I work as a cert’ed weld inspector.
I enjoyed reading you article and I have a few comments.
One possible reason for your previous feed issues is A) you are probably using vee-groove rollers, which will cause “wire shaving” with the soft 4043 wire, especially if you’re using a lot of pressure on your rollers. Those tiny shavings in turn end up clogging your guides, tip, and liner. (A lot of people will recommend 5356 with conventional wire feeders because of it’s higher yield strength.) With AL you should ONLY use smooth “U” groove rollers. And use the absolute minimum of roller pressure! You should be able to stop the wire feeding from the tip just by pinching it. It’s also helpful to get teflon wire guides as well. The copper ones, being harder than aluminum may also cause wire shaving.
If you can’t stop the wire easily with your fingers, chances are a jam will break the wire, cause a “bird’s nest”, and cost you a lot of time re-threading the wire. Even if it doesn’t break, trying to push through a hang-up with brute roller force might damage your plastic liner or guides.
The method of metal transfer with Al is quite different than what you’re probably used to when welding steel.
With only a 150 amp welder you’re using “short circuit transfer” with steel. With SCT if your Volts and WFS are tuned correctly, causes the crisp “crackling” sound, like peeling packing tape.
Al MUST be used in the “spray transfer” mode. (SCT doesn’t provide enough “cleaning action” to break through the tenacious surface oxide layer on any aluminum.) The spray transfer mode is very quiet, it sounds like frying an egg. When properly tuned, spatter should be only occasional.
For .030″ Al wire, spray transfer occurs between 500 IPM/22Volts, and 750IP/24V
For .035″ wire, good spray is between 400IPM/23V, and 700IPM/24V
Note that the latter requires between 120 and 200 amps. the former requires 100-150 amps. It’s questionable that your machine can produce reliable Al spray transfer weld with .035″. Therefore, with your underpowered machine I’d advise you to select .030″ wire and get a spool gun (with u-groove rollers) for best results. The small, delicate .030″ Al wire is likely to cause feed issues with traditional feeders no matter what you do.
Also, check out this website by Ed Craig who in my opinion is the world’s master of MIG welding.
http://www.weldreality.com/aluminum-welding-2.htmelding.