Spot welding of different metals-Copper

Resistance welding copper is perhaps the most difficult case owing to the high electrical and thermal conductivities of copper. If is not possible to obtain sufficient heat from the resistance of the metal or the joint and is therefore necessary to increase the resistance between the outer surface of the sheets and the tips. This can be realised by employing high resistant electrodes and low mechanical pressure. The heat at t he joint is produced by conduction from outside. It is extremely difficult to spot weld copper strips thicker than 1.5 mm.