Jing Bai

Date of Award


Degree Type


Degree Name

Master of Engineering Science


Electrical and Computer Engineering


Dr. Lyndon Brown


Resistance spot welding (RSW) is widely used as an efficient joining technology for assembling metal components in the automotive, biomedical and electronics industry. The demand for improved welding consistency has led to switching from voltage control to current control. In addition, commercially available micro-spot welders may also provide power control mode.

Power can be interpreted as the square root of the geometric mean of voltage and current. From this view point, the three existing power strategies can be seen as differently weighted geometric means of voltage and current. In fact, any weighted mean of voltage and current can be used as a viable control variable. Based on this insight, it is recognized that there should be one specific weighted mean of voltage and current that can lead to the least variance in the weld process. This provides a new tool for the weld engineer to maximize the quality of their welding processes. For welding 0.152mm gauge stainless steel, a 40% weighting on the voltage produced the most consistent weld nugget diameter was found. And with this control parameter, a 60% improvement in variance in weld nugget size versus constant current control was achieved.



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