Page 99 - Module DMV20173

5. 0 JOINING PROCESSES

5.3 RESISTANCE WELDING

1. Resistance welding is a process in which contacting metal surface are joined by the
heat obtained from resistance to electric current flow.

2. Equipped with water-cooled to keep the temperature low.
3. This process forms a small nugget at the interface of the two plates (Figure 5.7 (a))

4. The maximum thickness is about 3-4 mm.

5. Welding quality is dependent on the cleanliness of the material, free of dirt, scale and
other contaminants.

5.3.2 PROCESS SCHEMATIC

There are three stages in making spot weld (Figure 5.7 (b)):

1. Electrodes a brought together again the metal and pressure is applied.
2. Current is tuned on momentarily.

3. Hold stage, in which current is tuned off but pressure is continued, this hold time

forges the metal while cooling.

(a)

(b)

Figure 5.7 Welding small nugget area (a) Resistance welding process (b).

BPLK 131 DMV 20173