All we had at work were AC welders. I talked with the person at Airgas about welding aluminum. Go negative for aluminum instead of positive for a better weld on an AC welder, not as good as a DC welder, but I got the job done. I could get a quarter inch puddle instead of 1/16 or 1/8 puddle before blowing a hole through. About a month after I finished all my aluminum welding the welders were replaced with AC/DC models.