Spot welding is a kind of resistance welding method in which the weldment is assembled into a lap joint and pressed between two electrodes, and the base metal is melted by resistance heat to form a spot.

Spot welding can be divided into single spot welding and multi spot welding. Multi spot welding is a kind of spot welding which uses two or more pairs of electrodes to weld two or more spots at the same time or according to the automatic control procedure. Spot welding is an efficient, economical and important joining method, which is especially suitable for welding the stamping or rolling thin plate lap members with thickness less than 3 mm and without air tightness.

Spot welding is mainly used in the following aspects:

(1) Sheet stamping parts lap, such as car cab, car, harvester fish scale screen, etc.

(2) Thin plate and section steel structure and skin structure, such as car side wall and ceiling, trailer panel, combine funnel, etc.

(3) Screen, space frame and cross reinforcement, etc.