Study of Series Spot Welding (Part 2)

Application of Series Spot Welding

Abstract

Experiment has been conducted on shunting current and tensile shear strength in series spot welding without back up bar (Series clad welding) and series projection welding which are considered as applications of series spot welding. And theoretical consideration is made about shunting current in twin spot welding. Further the effect of prewelded spot existing between electrodes on shunting current is discussed.
As the result of experiment and consideration the following were concluded.
(1) For a mild steel lower plate thicker than 3 mm, good welding results are obtained by series spot welding without a back up bar when an upper plate of stainless or mild steel is 0.5-1.0 mm in thickness.
(2) Shunting current of series projection welding is about 20% larger than that of series spot welding.
(3) When a prewelded spot exists between electrodes, upper and lower plate currents decrease or increase depending on the position of the prewelded spot, but the sum of upper and lower plate currents remains constant.
(4) Shunting current of twin spot welding is 0.5-0.1 times as much as that of series spot welding.