Spot welding is a form of resistance welding. It is used primarily to weld thin sheet metal. It is a reliable and widely used technique. Spot welding is a process whereby the two pieces of sheet metal being joined are forced together between two thick copper electrodes. A high current is then passed between these electrodes through the spot being welded creating a short-circuit. Heat is generated by virtue of the material’s resistance causing the material to melt and fuse at the spot between the electrodes. No additional material is added as part of this joining process. Spot welding can be used for various metals, e.g. iron, but also aluminium.