Application of Friction Stir Spot Welding to Polypropylene Material on the CNC Machine and Determination of Optimum Welding Parameters

The Friction Stir Spot Welding (FSSW) method is a derivative of the Friction Stir Welding (FSW) process, which is a new welding process that recently has received considerable attention from the automotive and other industries. The studies of the different researchers, in this method tool geometry, tool rotation speed, tool penetration depth and dwell time had been indicated which effected the tensile shear strength of joining. In the study, 4 mm thick polypropylene (PP) sheets were done lap joints with FSSW in the CNC (Computer Numerical Control) machine. In the joining tool rotation speed, tool penetration depth and dwell time parameters by researching, in the strength of lap joint variation were examined. Welding process was applied with the aid of a written program using the ISO GM code system on the CNC vertical processing machine. In order to find the most optimum welding parameters, the welded samples were carried out the tensile tests according to TS EN 12814-2 standard. In this study, the maximum tensile force and the most optimum welding parameters have been determined as a result of tensile tests applied to the welded samples. The maximum tensile force has been achieved at the tool rotation speed of 1000 rpm, dwell time of 60 s and tool penetration depth of 6 mm. The maximum tensile force was obtained as 2907 N for the welded joining. This value is equivalent to approximately 50% of the base material.