Electric Welding

Electric Welding, a process of welding by aid of an electric current that heats to welding-point the two surfaces that are to be united. Suppose two wrought-iron bars are to be welded end to end, they are each gripped close to the portion that requires heating, and a very large current passed from one grip to the other along the intervening portions of the two wrought-iron bars. These are pressed closely together, but offer such resistance at their imperfect junction that they are rapidly rendered white-hot, and reach that special condition of fluidity that enables them to unite into one piece. At the junction they will bulge out when first united, and require subsequent hammering down. Alternating currents that have been transformed from fairly high potential to perhaps 10,000 amperes at low potential, are preferably employed, as they can be readily produced by a transformer and need not introduce much resistance into their circuits, except where the weld has to be performed. [Transformer, Welding.]