Friction stir spot welding of polycarbonate by a new design tool

Microstructures, tensile properties and fracture energy of a friction stir spot welded polycarbonate (FSSW) were studied at varying rotational rates and dwelling time. The problem of common FSSW welding is the remaining of characteristic keyhole. This can act as a concentration place in mechanical tests. To order solve this problem authors took advantage of innovation for designing the welding tool. The results show that in constant dwell time, strengths increase until 800 rpm and then decreases. In constant rotational speed (400, 800) the strength increase by increasing in dwell time but in 1600 rpm the best result was achieved in 10 Sec dwell time. Fracture energy which was exploit from stress-strain curve were in good agreement with strength of welds.