Optimization of process parameters on friction stir welding of high density polypropylene plate

Thermoplastic materials are now easily joined by friction stir welding. Joining of thermoplastics in friction stir welding which is based on frictional heat generated through contact between a rotating tool and the work piece. The determination of welding parameters plays an important role in weld strength. In friction stir welding of thermoplastics, traditional tools form a slit on the backside of welded specimen which leads to root defect causes poor tensile strength. Due to the high transparency of this polymer, it was to possible to analyse easily the morphological changes induced by the welding process on it. In this investigation the welding parameters studied were the tool rotation speed which varied between 800 and 1200 (rpm), transverse speed which varied between 40 and 200 (mm/min), axial force ranging from 1 to 5 (KN). An attempt was made to join the polypropylene plate of 5 mm thickness with different tool profiles (square, cylindrical and triangular threaded pin profile). The quality of the joint was evaluated by means of tensile strength and micro structural analysis. (C) 2014 The Authors. Published by Elsevier Ltd.