just bought a hobart handler 140 (already love it), and was just wondering on what gas to use for aluminum. my welder will be set up for mild steel (75% argon 25% CO2). it would be nice to be able to use this mix with aluminum as well, as it would be easy to just switch spools of wire, but the manual says to use a 100% argon mix when welding with aluminum. will the 25% CO2 make a difference welding aluminum?
I can't find a reference, but I think aluminum may react with CO2. Aluminum is produced by reacting aluminum oxide with carbon when electrical energy is injected, so I guess that the reaction may go backwards and produce energy
You MUST use 100% Ar for MIG welding aluminum. Molten Al is highly reactive. Al powder is the active ingredient in thermite, for example. It will react with CO2, stripping away the oxygen and creating a nasty mess. Also, you really need a MIG welder with twice as much current output. along the lines of 200-300 amps. 130 amps will not perform well even with a spool gun, and running the weak, prone-to-jamming .030 Al wire. You could try to do it that way, but I would not advise. (There is no way in hell you'd be able to cram wimpy .030 Al wire through a 6 foot traditional welding lead. It'll kink and jam after 5 seconds.) MIG welding aluminum REQUIRES using the high-current, high feed speed, spray transfer mode. Here are some typical parameters: 030 wire, 500 IPM, 22 volts. 120-130 amps. 035 wire, 500 IPM, 23 volts, 150 amps. 045 wire, 400 IPM, 24 volts, 200 amps. EDIT, the guy above me has the right idea. They use electricity to force the reaction between aluminum oxide (dissolved in cryolite) and carbon, producing molten Al and CO2 gas. Normally the reaction would tend to go the other way. Aluminum has a higher affinity for oxygen.
Get the kit which will have new drive wheels and the liner, and get the right gas, and don't plan on using any thin aluminum, I was never able to have fine enough control on my machine to get it to work well on anything less than 1/8 material. Also, you will probably buildup too much heat and burn through if you try to go far, weld about 1 at a time and let the material cool. Your machine and mine are just barely on the edge of being capable of doing this. It is nearly impossible to dial it in to a reliable point.
