Influence of Pin Profile on Quality of Friction Stir Lap Welds in Carbon Fiber Reinforced Polypropylene Composite

In recent years, interest on friction stir welding has grown more since such a joining technique allows welding of light weight alloys like aluminum and its alloys which are difficult to weld or even unweldable with the traditional fusion welding processes. This process can also be one of the joining processes considered for welding polymer matrix composites such as polypropylene composites which find a number of applications in different industries. This paper presents the effect of tool pin profile on surface appearance and tensile shear strength of friction stir lap welds in carbon fiber reinforced poly- propylene composites with 4 mm thickness. Four high speed steel tools with different pinprofiles of threaded cylindrical, threaded cylindrical-conical, simple cylindrical-conical and threaded conical were employed for this study. Using these tools, lap welds were made under similar conditions of tool rotational speed, welding speed and tilt angle. Specimens were prepared for tensile shear testing. The tensile shear test results showed that the threaded cylindrical-conical tool produced a weld with better surface appearance and higher tensile shear strength.