Projection welding is similar to spot welding but for the fact that the welding takes place at the projections on the surface of the metals and flat shaped electrodes are employed. The projection present in the material to be welded can be used for localisation of spot heating. In most cases, a projection is created at the required place by pressing, milling or turning. When a current is passed, the projection gets heated up (the heating being dependent on the dimensions of the projection). The projection is squeezed by the application of electrode force. Projection can be round, oval, oblong, square or any convenient shape.