Experimental optimization of the mechanical properties of friction stir welded Acrylonitrile Butadiene Styrene sheets

One of the joining methods of engineering thermoplastics is friction stir welding which is based on frictional heat generated through contact between a rotating tool and the workpiece. In this article, Acrylonitrile Butadiene Styrene sheets are friction stir welded using a metallic tool. Mechanical properties of the welded sheets are investigated under varying processing parameters. Empirical welds are performed using design of experiment theorem and analyzed by statistical methods. The main factors are geometry of the tools such as pin profile, diameters ratio, and welding process parameters include rotational and linear speeds. The orientation of the tool is another important factor, named tilt angle. A fully central composite design for welding process is assessed using analysis of variance and is optimized through response surface methodology. Tensile yield stress is considered as response of designed process experimentally by standard test method. Analytical and experimental results showed an optimized weld strength up to 97% and 101% respectively for cylindrical and conical pinned tools compared to tensile strength of the parent ABS sheet. Finally, significant factors and optimal conditions obtained to be 2° of tilt angle, 900 rpm for rotational speed, a conical tool with diameters ratio of 20/6 and linear speed of 25 mm/min.