Resistance Seam Welding
This is similar to spot welding except that the copper alloy electrodes are in the form of circular rollers. The overlapping sheets are held under constant pressure between the roller electrodes, which rotate at constant speed and carry current. A series of spot welds whose nuggets are overlapping on each other are formed which give the appearance of a continuous seam. The process is employed in fabrication of oil I tar drums, railway coaches, automobile industries and transformer cooling fin fabrication, etc.