Friction stir welding of thermoplastics using a newly designed tool

•Successfully eliminating root defect of ABS welded sheets using newly designed FSW tool.•Investigation of the effect of FSW parameters on tensile strength of welded specimens.•Obtaining higher tensile strength using convex pin.•Observation three different fracture modes regardless of pin shape.•Meaningful relationship between tensile strength and processing parameters.

Although friction stir welding (FSW) is a recent addition to plastics joining technology, it has been shown to have many benefits over traditional welding, particularly in terms of joint quality. In FSW of thermoplastics, traditional tools usually form a slit on the backside of the welded specimens. Therefore, a serious problem named “root defect” occurred and leads to a poor tensile strength of the workpiece. In this paper, a newly designed tool with two shoulders, touches upper and beneath surface of the workpiece has been used in order to weld acrylonitrile butadiene styrene (ABS) sheets. The new tool named, “self-reacting tool”, successfully eliminated back slit of the welded parts. Moreover Shape of the pin (simple and convex), rotational speed and translational speed are used in experimentations as the variable parameters affecting mechanical properties. Tensile strength is considered as the mechanical property of welded parts in this research. Obtained results show that pin shape has the greatest effect on tensile strength of welded parts.