Weld current has been recognized as an extremely important parameter since the development of the resistance welding process. Together with time (cycles) and electrode force, weld current directly affects weld quality and appearance.

Fortunately, in many applications of resistance welding, some margin of error exists with respect to most weld parameters. However, with some newer metals, including coated and high-strength low-alloy (HSLA) steel and aluminum, the control of welding parameters over a narrower range has become more important. Also, special kinds of welds, such as those involving projection welded fasteners, pose unique requirements. Weld monitoring can help fabricators improve productivity when performing these types of welds.

In its simplest form, a weld monitor is a current sensor combined with a display that gives a readout of weld current in amperes. Some monitors allow the setting of high and low limits, or tolerances, on the acceptable range of current and weld cycles. Other monitors add sensing of electrode voltage and can calculate resistance. Still others can measure electrode force and displacement (tip movement during the weld).

Depending on your application, monitoring one or all of these parameters can help you make improvements in quality and productivity. Next >>