Resistance WeldingResistance welding describes a number of non-fusion processes used for welding a range of materials. In these processes an electric current is passed through materials held between two copper electrodes and heat is generated in those materials due to their electrical resistance. Pressure is also applied to the materials by the electrodes to effect the welding operation. Processes included in this group are resistance butt-welding, resistance spot-welding, flash-butt welding, and resistance seam welding. In most processes the electrodes are cylindrical with shaped contact ends but for seam welding the electrodes are in the form of wheels or rollers. The equipment for all resistance welding is of an automatic, robotic or semi-automatic type. In semi-automatic mode an operator is required to position the welding head and initiate the welding sequence. Equipment is normally expensive and even more so for robotic operation. No filler metal or shielding gases is used in these processes. The processes are used mainly in such applications as car and vehicle production lines, and manufacture of aeroplanes. They are normally restricted to welding materials under 3 to 4mm thick. The main safety issues and electrical, hot metal ejection, and possibly, noise.
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