What is the difference betwwen AC and DC TIG welder?
DC is Direct Current. It's fairly self explanatory and used for welding mild steel, stainless, cast iron, etc. Current only flows directly to the work piece.
AC or Alternating Current turns your torch into a ray gun! When the machine is switched into AC you can set it to switch back and forth between the torch being positive and negative 10–300 times per second! The main use of this function is for aluminum welding. Aluminum has what's essentially two layers, the base aluminum, and aluminum oxide protecting the base metal. The base metal has a melting point of only 660 degrees, while the oxides don't melt until past 1200 degrees. Because of this the oxide must be cleaned off or else the parent metal will liquefy before the arc even makes it through the oxide layer, this is where AC comes in. As the current cycles to the torch being positive, the shielding gas becomes ionized and blows or cleans the oxide layer off. This is called ionic bombardment. The cleaning action of AC is what allows aluminum to be welded.
