Resistance Welding

This paper is directed to engineers interested in the application of resistance welding to the industries. The discussion foreshadows some of the latest tendencies of development. It deals with some fundamentals of design though it is not written as a complete treatise on the subject, nor especially for those engaged in the designing of resistance welding machinery. Differentiation is made between the older form of resistance butt welding and the later method of flash butt welding. The probable action taking place in the flashing zone is discussed, along with the effect that increased potential across the weld has on this action. The main object in flash butt welder designing should be to combine the maximum degree of acceleration of the metals into the flashing zone with the proper and necessary e. m. f. A study of the power division of a typical butt welder shows that the efficiency may be as low as 7 per cent or lower, but that nevertheless it competes with other methods of welding when applied to problems of mass production. The effect of external resistance in a flash butt welding machine is to offset variations in die contact and variations in stock resistance, thus stabilizing the flow of current in the flashing zone. The power factor of welding machines is not regarded by the designers as a major element, since the time of application of the current is at most but a few seconds.