An approach to weld dissimilar polycarbonate and high-density polyethylene by friction stir spot welding

The friction stir spot welding of polymeric materials has been examined extensively; conversely, only a few researchers have addressed the friction stir spot welding of dissimilar polymers. In this study, the possibility of friction stir spot welding of dissimilar polycarbonate to high-density polyethylene is examined, which has not been previously investigated. The influence of welding parameters, namely, tool rotational speed and dwell time, was investigated experimentally, whereas the plunging depth, plunging rate, and tool geometry were kept constant during all tests. The induced temperature and the weld lap shear force were recorded and analyzed. Both materials are welded successfully by friction stir spot welding. At 2300 rpm and 40 s dwell time when the polycarbonate sheet was on the top, the maximum lap shear force of 0.37 kN was obtained. The findings demonstrated that an effective weld might be attained at a moderate frictional heating temperature slightly below the melting temperature Tm and glass transition temperature Tg of both welded materials. At very low temperatures, poor weld quality was obtained. When temperatures extensively increased, the results deteriorated to exhibit weak joint lap shear values because of the presence of cavities and pores in the weld junction.