The New Student's Reference Work/Electric Welding

Electric Welding, the process of welding two pieces of metal together by using the heat produced by an electric current. The process developed by Elihu Thomson is practically the only one used. In this the pieces to be welded are held in proper supports, and a large electric current at a very low pressure is sent through the joint from piece to piece. The passage of a large current causes a local production of heat in the metals on each side of the joint, and the metals are pressed together when at the proper temperature, a perfect weld being formed. Practically all kinds of metals can be welded in this way, and even different metals can be welded together, as copper and brass. Welds can also be made by this method in pieces whose shape would prevent welding by ordinary processes. The current used is an alternating current, often of thirty or forty thousand amperes and of correspondingly low pressure. Welding-currents are produced by a special transformer which forms part of the apparatus. The apparatus takes different forms, depending on the shape and size of the work to be handled. For joining two wires it has a very simple form, but for welding pipe or welding artillery-projectiles machines of special form are required.