Preliminary study on friction stir spot welding of plastic sheets with non-metallic tools

Abstract

In recent years, 3D printing technology of engineering plastics is often used in various fields to develop prototypes of parts. Friction stir spot welding of lap joints of different engineering plastics has considerable potential for industrial applications. This study used a self-developed non-metallic tool to successfully form the PLA joints on a modified conventional drilling machine. The results show the average downward force and average welding torque decreased with increasing the rotating speeds and dwell times. The stir zone width is slightly increased with increasing the rotating speed, and its signification increased with the dwell time. The increase in stir zone width on the different rotating speeds and the dwell times is similar to the increasing trend in average temperature. The average temperature multiplied by the dwell time defined as the bonding factors is similar to the diffusion bonding. The stir zone width is increased with increasing the bonding factor because there has still some distance between the shoulder to the lap surface, the stir action by the shoulder is not easy riches to the lap surface, so the stir zone only occurs within the FSP zone and the stir zone width never exceeds the shoulder diameter.