Direct current provides a much quieter, more stable arc, with much less spatter on the finished weldment. It is the preferred setup for most serious welding, aside from a few odd situations (such as severe arc blow), and tig welding on aluminum (where the positive side of the AC cycle is needed in order to break through the oxide layer covering the surface of the aluminum). The popularity of AC only machines is due to their low price tag and near indestructibility, which are both great if you don’t burn rod all day. The price of an AC/DC machine is typically 1.5 to 2 times that of an AC only unit, but if you plan on welding all day you might appreciate the increase in control provided by A DC machine. Don’t get me wrong... AC machines work, but DC is a whole lot friendlier. |