DOUBLE-SIDED FRICTION STIR WELDING OF POLYCARBONATE

Double-sided friction stir welding (DS-FSW) involves welding on one side of the material and then reversing it to weld on the opposite side. The process is similar to conventional FSW, where the material is joined by the mechanical action of a rotating tool. DS-FSW is particularly useful for creating strong, defect-free joints in thick materials. The primary objective of this study is to test the effect of process parameters on the quality of welds produced by DS-FSW. The parameters under investigation include tool shape (cylindrical vs. threaded), welding direction (advancing vs. retreating sides), and plunge depth (no weld overlap vs. overlap through the thickness). Full factorial design of experiments was conducted to test the combined effect of the joining parameters. The material used herein is polycarbonate (PC) with a 6.35-mm thickness and the experiments were conducted with constant feed rate and tool rotational speed. Additionally, temperature distribution during welding was monitored using a thermal camera. The strength of the welds was evaluated through tensile tests, and the welded joint was visually inspected for defects. It was found that the maximum joint strength was obtained with threaded tool, same advancing side along the seam, no dwell time, and overlapping weld nugget. The results provide valuable insights into the effects of welding process parameters and guide future applications of DS-FSW in polymeric materials.