Drawn Arc Welding process

At the point that the start button/ trigger has been depressed, the equipment allows approximately 40V to pass through the pilot cable, which energises the handtool solenoid, at the base of the handtool body.  

At this point the main shaft now lifts up into the centre of the energised coil, thus lifting the weld stud from the work piece in order for the pilot arc to establish, subsequently progressing to the main arc.

At this time the shaft has started to plunge back towards the molten work piece, all of which is contained within the ceramic ferrule.

At this point the two materials have bonded causing a welded stud.   

See figure below for the sequence.