What cleaning action occurs during electrode positive mode?

In electrode positive mode, also known as reverse polarity, the workpiece acts as the anode while the tungsten electrode is the cathode. This configuration results in a significant cleaning action where contaminants such as oxides and other surface impurities are effectively removed from the work surface.

The cleaning effect occurs because the positive workpiece attracts electrons, which helps to break down the oxide layers and other contaminants, leaving a cleaner surface for welding. This is particularly important when working with materials like aluminum or stainless steel, where a clean surface is essential for achieving a good quality weld.

The other options revolve around different aspects of welding. While heating the workpiece more effectively relates to the overall energy input in welding, the primary action in electrode positive mode is the cleaning of the surface. Similarly, the lifespan of the tungsten electrode and the amount of shielding gas required are influenced by other factors, but they do not directly pertain to the cleaning action that takes place during reverse polarity.