RESISTANCE WELDING

This is a process of welding in which heat is obtained from resistance of the work to the flow of current and then applying pressure. No filler metal or flux is added.
PRINCIPLE OF RESISTANCE WELDING:
In this welding,a low voltage(typically 1 volt) and very high current(typically 15000 A)is passed to the point for a very short time(typically 0.25 sec). This high ampere current heats the joint.The following are the types of resistance welding.
-Spot welding
-Seam welding
-Projection welding
-Resistance butt welding
-Flash butt welding
-Percussion welding
Electrodes for resistance welding: Since electrodes carry large amount of current/ pressure and also help to remove the heat from weld zone. Thus to prevent overheating, the electrodes must have higher electrical conductivity and hardness, hence copper alloys are preferred.
Copper-Cadmium for welding Al and Mg.
Copper-Chromium for welding MS and low alloy steels.

Go through the advantages/ disadvantages and uses for every type of welding.