Effect of different tool pin geometries on force, torque, microstructure and mechanical properties of friction stir welded acrylonitrile butadiene styrene and polycarbonate joints

In this research, the effect of tool pin geometry on the development of heat, torque and force during friction stir welding of acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) plate by using double shoulder tool was examined. The overarching aim is to investigate a suitable tool pin geometry that can provide a considerable amount of weld properties. The experiments were conducted with L₉ orthogonal array full factorial design based on the Taguchi method by considering a combination of two factors and three levels. Three different pin profiles, including plane tapered, threaded cylindrical and threaded tapered tool pin profile were considered with varying tool rotational speed (800, 1200, and 1600 rpm). The variation in microstructure and mechanical properties with the change of torque, forces and heat input generated during weld is observed and analyzed. A maximum ultimate tensile strength (UTS) of 21.61 MPa and joint efficiency of 70.55% was obtained at 1600 rpm by using tapered threaded tool pin profile. Microstructural analysis of maximum UTS revealed thin and uniform interface layer with mechanical transportation phenomenon.