DC (direct current) is usually used for welding stainless steel and mild and low alloy ... only its 212 Auto-Set MIG, on which you simply set the wire size and metal thickness before welding ...

The Millermatic 180 and 211 Auto-Set MIG welders take all the guesswork out of MIG welding by allowing the user to simply choose material thickness ... to 3/8-inch mild steel.

Arc welding using the Metal ... wire electrode the negative pole is connected to the work piece. If the oxide film is thick (oxidised aluminium work pieces), the film has to be removed mechanically ...