Current and weld time is pre-set to suit the diameter to be welded

The stud is then placed on the plate.

Upon triggering a pilot arc occurs as the stud lifts to a pre-set height. The main arc in the weld end of the stud and creates a molten pool in the plate.

Return spring pressure forces the stud into the molten pool. The ferrule contains the molten metal and shapes the fillet.