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Spot welding

Joining process where two sheets are joined by heat and pressure created by two conductive electrodes.

Illustration of Spot welding

The process

Two plates [1] are placed together first and then positioned between two water-cooled metal rods [2]. The metal rods act as electrodes and are connected to an external power source. The electrodes are then pressed together to plates which in turn is pressed together causing a current to be passed through the plates.

The result is that the material is melted at the contact point [3] due to the large thermal energy generated by the current and pressure. Power is cut when a certain amount of heat energy is reached at the point of contact. After the plates have fused together, and after the weld has been partially cooled, the electrodes are removed from the plates and the bonding process is complete.