Recent Developments in the Monitoring of Resistance Welding in Mass Production Industries

There is a growing tendency towards the development of more sophisticated microprocessor or computer based control and monitoring systems for resistance welding. The need for such equipment is self-evident, however, there is an even greater need for simple, cheap devices which permit the accurate setting up and routine checking of the basic welding parameters and condition of the equipment. Two such parameters are electrode force and secondary resistance and recent developments in transducers and electronics permit both to be easily measured.

A force measuring system has been built which is capable not only of measuring the maximum electrode force obtained in a welding cycle but also gives the value at the point when weld current is initiated. Such equipment permits the optimum squeeze time to be set so as to prevent the current initiation on a rising pressure cycle. Developments in electronics now permit the measurement of true resistance in the presence of high currents even in inductive circuits. This has permitted the building of an instrument capable of either checking the total secondary resistance or the resistance of individual components such as cable resistances or the resistance between electrode caps and their holders.