We addressed a part manufacturer with a four-station carousel arrangement used to manufacture separate, but similar, resistance spot welds on a part (See Figure 1). To simplify the weld setup, a common weld current level was desired for all four weld guns. Work was done to evaluate the weld current level and current range (minimum to expulsion) for each weld gun in the carousel. This effort comprised evaluations using different weld times and electrode geometries to pick the optimum welding conditions for the application. The weld current and current range compatibility is illustrated in this article.
Figure 1 – Arrangement of the Four Weld Gun Carousel
The electrodes included two types of radius-faced and a truncated cone electrode design. Weld times ranged from 115 ms (7 cycles) to 300 ms (20 cycles) weld time and weld force at a nominal and higher force. There were differences noted in the current levels based on electrode geometry. One weld electrode style, the weld times and force levels were selected for evaluation based on the initial test data for the four guns.
Figures 2 and 3 illustrate the effect of weld time and Figure 4 illustrates the effect of increased weld force on weld current compatibility.
Figure 2 - Weld Current Compatibility Between Four Weld Guns at 110 ms Weld Time
Figure 3 - Weld Current Compatibility Between Four Weld Guns at 300 ms Weld Time
Figure 4 - Weld Current Compatibility between Four Weld Guns at Higher Weld Force
After selecting the electrode style, the optimum weld current level and force settings were identified for use on all four guns. Either the 110 ms or 300 ms weld time could be used for welding the component because of the easily manufacturable current ranges. However, a single electrode force was specified and needed to monitored more closely.
This article also appeared in the American Welding Society - Detroit Section Sept. 22 e-Bulletin.
Warren Peterson
Welding Technical Director
United Technical Solutions