Construction Features of Special Resistance Welding Machines

Although the design of so-called standard resistance welders is more or less fixed, the construction of a special resistance welding machine involves a series of design factors which are only approximate and for which one allows large limits. An attempt is made to outline the elementary features of construction for successful operation by enumerating the factors which must be known. A method of obtaining the proper transformer capacity, types of switches for changing the amount of welding current, and means for regulating the time of application of the current are indicated. Important mechanical conditions to be considered are also touched upon. This is followed by a description of the construction features of a few outstanding resistance welding machines of special design used at the Hawthorne Plant of the Western Electric Company. Although most of these machines are of relatively small total current capacities, the current densities used are quite high. The machines described are used for welding precious metal contacts, permalloy wire, bronze brushes, switchboard plug parts and copper rod.