In ___________, the heat required for welding is generated through friction at the interface of the two components being joined. In friction welding, one of the components remains stationary ( 固定的) while the other is placed in a chuck( 卡盘 )or collet( 夹头 )and rotated at a high constant speed.The two members to be joined are then brought into contact under an axial force.After sufficient contact is established, the rotating member is brought to a quick stop (so that the weld is not destroyed by shearing ), while the axial force is increased. Oxides and other contaminants at the interface are removed by the radially outward movement (径向排除) of the hot metal at the interface.The pressure at the interface and the resulting friction produce sufficient heat for a strong joint to form.The shape of the welded joint depends on the rotational speed and on the axial pressure applied. These factors must be controlled to obtain a uniformly strong joint.