Is it possible to weld aluminum with a MIG welder? Can I just change out my spool of wire for some other type that will work with aluminum? Can I use 75-25 argon as shielding gas still? Will the results be worth the effort?
The 75-25 your currently using is more than likely 75%-Argon/25%-Co2. That is exactly what you want to weld mild-steel and, nothing else.
The Co2 in this mix "WILL" absolutly cause porosity when you weld aluminum. In laymen terms it will pretty much blow-up when you try to srike an arc.
As far as gas is concerned when welding aluminum MIG/TIG can be considered identicle. By that I mean to ONLY use PURE argon.
Now these guys are "TELLING" you to get a spool gun without explaning WHY. Aluminum is soft as shit. YOU know this I'm shure. That liner that connects the power source to the mig gun is usually about 10" in length.
Lets say you just throw in an aluminum spool. The spool is fed to the drive rollers. The drive rollers push the wire through that +/-10" liner and into the mig gun and then the contact tip.
If sized right for the wire-size your using, the contact tip will create enough resistance that the Aluminum wire will coil up inside the liner to the point you'll end up with a birdnest. Anyone that has MIG welded before will have fuked-up at some piont and welded the wire to the contact tip and kept holding the trigger down. Then you flip up the side cover on the power source where the wire spool is, to find a nice little bird nest of wasted wire.
The reason for the "SPOOL-GUN" is that it shortens the distance between wire-spool and drive-roller to contact tip to a few inches. They use a small +/- 1lbs wire roll. There are also stainless and mild-steel rolls that will fit in a spool-gun.
If you were MIG/TIG welding overhead you could use a Argon/Helium Mix because the helium, being lighter than air will help with shielding. Also a helium mix will "BURN" hotter than pure argon and could be paired up with a low power machine to increase output. But seriously dont even try this unless you have the money to experiment.
Welding is one of those things where you just have to try all kinds of setups on scrap or non-critical parts, along with some decent research and talking with other welders untill you find out what really works.
daroberts3 To directly directly answer your question, fuck yeah you can MIG weld aluminum. Use a Pure argon mix and a spool gun.
