The process „drawn arc stud welding with shielding gas“ is used for welding studs of a diameter of 3 to 12 mm ( 16mm). In general, the positive pole of the power-source is connected to the workpiece. The stud will be inserted into the chuck of the stud welding gun and positioned onto the workpiece, possibly by adding a ceramic ferrule.
Initiating the welding process: by means of a lifting mechanism, the stud will be lifted and at first an auxiliary arc (pilot arc) of a low current will be drawn. Then the main arc will be drawn between the tip of the stud and the workpiece. The main arc of a high amperage must be adjusted to the diameter of the stud. The cross sectional area of the stud and the opposite workpiece a partially melting.
After the lapse of the adjusted welding time, the stud is moved towards the work piece and both melting zones join tightly. The power-source turns off, the melting zone solidifies and cools down.
In order to obtain a good gas-protection, an adequate appliance is indispensable. At the upper part of the chuck, the gas chamber should be sealed by means of a rubber sleeve.
Down at the workpiece, lateral slotts are required to allow the gas to escape.
The use of appropriate shielding gas is of great importance: mild steel and stainless steel: 82% Ar and 18% Co2, for aluminium; pure Argon or Ar and He.
