This process of friction stir welding is mainly used for joining aluminum, magnesium and other metals. It avoids the problems associated with melting, such as cracks, porosity or reduced strength in the weld area, and it is commonly used in industries such as aerospace, automotive and shipbuilding. The equipment requirements for friction stir welding are not very high; the most basic requirement is the rotational motion of the weld head and the relative motion of the workpiece, and even a milling machine can simply fulfill the requirements for small flat plate butt welding. However, the rigidity of the welding equipment and fixture is extremely important. Stir heads are generally made of tool steel and the length of the head is generally slightly shorter than the required depth of the weld. It should be noted that the friction stir weld ends with a keyhole in the terminal. Usually this keyhole can be removed or sealed by other welding methods. To solve the keyhole problem, a telescopic stirring head has been developed, which does not leave a weld keyhole after welding.