Stud Welding Aluminum.

Stud welding Aluminum may be accomplished with conventional arc stud welding equipment, using either the capacitor discharge or drawn arc capacitor discharge techniques. The conventional arc stud welding process may be used to weld aluminum studs 3/16 to 3/4 in. (4.7 to 19.0 mm) diameter. The aluminum stud welding gun is modified slightly by the addition of a special adapter for the control of the high purity shielding gases used during the welding cycle. An added accessory control for controlling the plunging of the stud at the completion of the weld cycle adds materially to the quality of weld and reduces spatter loss. Reverse polarity is used, with the electrode gun positive and the workpiece negative. A small cylindrical or cone shaped projection on the end of the aluminum stud initiates the arc and helps establish the longer arc length required for aluminum welding.

The unshielded capacitor discharge or drawn arc capacitor discharge stud welding processes are used with aluminum studs 1/16 to 1/4 in. (1.6 to 6.4 mm) diameter. Capacitor discharge welding uses a low voltage electrostatic storage system, in which the weld energy is stored at a low voltage in capacitors with high capacitance as a power source. In the capacitor discharge stud welding process, a small tip or projection on the end of the stud is used for arc initiation. The drawn arc capacitor discharge stud welding process uses a stud with a pointed or slightly rounded end. It does not require a serrated tip or projection on the end of the stud for arc initiation. In both cases, the weld cycle is similar to the conventional stud welding process. However, use of the projection on the base of the stud provides the most consistent welding. The short arcing time of the capacitor discharge process limits the melting so that shallow penetration of the workpiece results. The minimum aluminum work thickness considered practical is 0.032 in. (0.800 mm).