Welding electrodes are installed in the weld head to touch and maintain contact with the workpieces through the full weld schedule. The welding electrodes play three different roles in resistance welding:
maintaining uniform current density, concentrating current at welding points, and maintaining thermal balance during welding.
Electrodes are available in many shapes. Electrode material and shape are determined by considering the force necessary for welding and the thermal conductivity of the workpieces.
In conventional macro-welding, e.g. car body assembly, the electrodes are made of copper alloys and usually water-cooled. However, in micro-welding, the electrodes are made of a wide variety of conductive and refractory materials depending on the parts to be joined, and are air-cooled.
For more information about the resistance welding process read our Fundamentals of Resistance Welding.
Also see: RWMA 11, RWMA 13, RWM14, RWMA 2, RWMA 3