ELECTRIC RESISTANCE WELDING
Electric resistance welding is an important and widely applied non fusion welding process. This write up covers the basic principles of various resistance welding processes, effects of the parameters, applications of these processes and the equipments needed for them. When a high electric current is passed through a small area of two butting metal surfaces, heat is generated at the Interface.
Heat generated H = I2 x R x t
Where
I = current passed
R = resistance of the interface
t = time of application of current.
When the interface attains a coalescent state, a huge pressure is applied to the heated interface to form the weld joint. Sheets, tubes, wires or even rods can be welded using various resistance welding processes. The parameters viz., current, time of application of current, pressure, duration of pressure applied and electrodes depend on the process used, materials to be welded, thickness of the job and also the application to which the welded joint is put in.