The experiments of plastics FSW with different dimensional stir tools were carried out. The tests showed that a full and
smooth joint can be obtained with 30 mm in
shoulder diameter, 10 mm in pin diameter, 1660 r/min in rotation speed and 25 mm/min in welding speed. The welding temperature was directly proportional to rotation speed. The effect of welding speed was complex,
increasing welding speed reduced the heat input and increased the normal force Fx acting on the pin, friction heat power and welding temperature. The diameter of tool shoulder can affect the friction heat power between the shoulder and the welded surface, increasing the diameter of tool shoulder can increase the welding temperature and be helpful for the overflow and splash of the welding material. The effect of pin diameter is complicated, increasing the diameter increases the relative sliding speed between the pin and the welded material, which leads to the increasing of the welding temperature, meanwhile increasing the diameter increases the endotherm power and the area for heat transfer, which reduces the welding temperature.