2. Describing arc stud welding as 6 steps

1. The stud is positioned in the gun collet, with the stud protruding slightly from the protective flash shield.
2. Press the stud against the work surface to complete the necessary circuits. Press the trigger to initiate the weld cycle.
3. When the gun solenoid is energized, the stud is withdrawn from the work surface, inducing a pilot arc which cleans both the stud and work surface.
4. The controller automatically releases the main welding current. This weld arc causes a pool of molten metal to form at the base of the stud and on the work surface.
5. The controller then de-energizes the gun solenoid, allowing the stud to plunge back into the molten metal. As the weld pool solidifies, it forms a homogeneous joint.
6. Withdraw the weld gun from the welded stud, and position the next stud in the gun collet.

(The source of the following description is different from the above.)

Drawn arc stud welding is a process by which a metal stud is joined to a metal workpiece by heating both parts with an electrical arc. It permits strong, one-sided welds on base metals with thicknesses starting at 0.048" (1.2 mm), and produces welds in as little as 0.06 seconds.
A key factor that differentiates stud welding from other fastening processes is that the fastener is attached to the workpiece without marring the other side. This method provides highly reliable fastening for a wide variety of applications and allows almost any size or configuration of a metal stud to be welded quickly to a workpiece, while providing maximum weld penetration and reliability.
The process utilizes a DC power supply to create the arc, a stud welding tool, metal fasteners, and in some cases, ferrules.
There are three common techniques:
Drawn Arc Stud Welding ? For this technique, a flux loaded stud is loaded into the stud weld tool chuck, and a ferrule (a disposable ceramic shield that contains the molten pool of metal) is placed over the end.
Short Arc Stud Welding ? While this process is similar to drawn arc, it does not use a flux load or ferrule. It also offers the shortest welding times of all the drawn arc stud welding options.
Gas Arc Stud Welding ? As it employs insert shielding gas with no flux or ferrule, this process is easier to automate, although it provides less fillet control and less depth of penetration in comparison with the drawn arc technique.