Investigation of the Effect on Joining Strength of the Tool Geometry in the Friction Stir Spot Welding Applied to Polypropylene Material

Friction stir spot welding (FSSW) method is prone to automation. In this way, by integrating the robot and automation systems have been easily developed. Thanks to the method, the effective overlapping joints can be obtained a short processing time. In the study, 4 mm thick polypropylene (PP) sheets were done lap joints with FSSW in the CNC machine. On the two different tool geometries were studied and the effect on weld joining strength of the tool geometry was 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 tool geometry, 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 tool geometry have been determined as a result of tensile tests applied to the welded samples. The maximum tensile force with the Tool 2 has been achieved at the tool rotation speed of 1000 rpm, dwell time of 90 s, tool penetration depth of 5,75 mm. The maximum tensile force with Tool 2 was obtained as 4038 N for the welded joining. This value is equivalent to approximately 70% of the base material.