The impact of process parameters and pin-to-shoulder diameter ratio on the welding performance of polycarbonate in FSW

Abstract

The utilization of friction stir welding (FSW) for the joining of polymers and composites is gaining increasing recognition due to its capabilities. In this study, the weldability of 4 mm thick polycarbonate (PC) plates in FSW is examined. Statistical modeling tools were employed to investigate the effect of four control parameters, i.e., rotational speed, travel speed, weld tool shoulder, and pin diameter, on the geometrical characteristics (residual thickness) of the weld region and the mechanical performance of the weld components under flexural and tensile loads. A screening experimental procedure with an L9 Taguchi was initially performed to calibrate the control parameter levels. During the welding procedure, the temperature profiles were continuously recorded to verify the materials’ solid state. The welding efficiency of the joint was also assessed, with a 90% welding efficiency achieved in the study. The morphological characteristics of the welded zones were assessed through optical and scanning electron microscopy. The samples welded with 4 mm/min travel speed, 10 mm shoulder diameter, 1000 rpm rotational speed, and 3 mm pin diameter had the highest mechanical performance. Overall, a shoulder-to-pin diameter ratio between 2.5 and 3 achieved the best results. The findings provide valuable information for the weld performance optimization of PC sheets, which can be employed successfully in real-life uses. Graphical abstract