Thread: MIG Welding Aluminum
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Unread 05-07-2005, 00:26
eugenebrooks eugenebrooks is offline
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Re: MIG Welding Aluminum
Quote:
Originally Posted by sanddrag
I know you can weld aluminum with a MIG welder, but do you absolutely need a spool gun? I've read a few manuals that just say use 100% argon gas and a larger tip for expansion and so on and so forth. No mention of a spool gun. So, does it really work? If not, how much do spool guns (and related/required accessories) cost?
SandDrag:

I did the welding on 1280's robot last year. There were both sections of 1/8 aluminum in 6061-T6, flanges on 1/2 axles in 4130 steel that we heat treated after welding, and other small parts. We used a Lincoln TIG-185 with a water cooled torch adapted to it. The rig was pretty close to topped out when welding the aluminun and the heaviest steel pieces. The water cooled torch was pretty essential at these currents.

The spool gun is optional, it's role is to avoid kinking in the wire feed when attempting to weld soft aluminum wire. If you already have a MIG welder, you can try it out with aluminum wire and see if the welder is capable of dealing with the welding you want to do before investing in a spool gun.

Inexpensive MIG welders can run a little short on voltage/current when attemtping to weld aluminum. Aluminum conducts heat away from the weld like a bandit. Aluminum is welded "hot and fast" in order to minimize heat input to the material so that the heat treatment is not unduly affected. Your typical 115 volt MIG welder will not be capable of welding 1/8 aluminum and this thickness of material is likely to appear on a FIRST robot.

Although I would reccomend a TIG welder for aluminum, if you are going to buy a MIG rig for aluminum I would be very careful to check the process limits for the welder you are considering buying. The brochures available for the Lincoln SP-135 and SP-175 indicate that you will need at least the SP-175 in order to deal with 1/8 inch aluminum. Remember that power is voltage times current, and some welders might have impressive current figures while falling down a bit in voltage, and therefore come up short in delivering heat.

Have fun,
Eugene