2. Controlled friction

2.1 Principle

Developed first, controlled friction welding involves welding on a direct-drive machine, i.e. one in which the motor supplies the friction torque directly during the heating-up phase.

Such a machine schematically comprises (figure 2 a ) :

• a rotating chuck attached to a spindle driven by the motor via a clutch and brake;

• a non-rotating chuck or vice, coaxial with the first, associated with an approaching table and capable of exerting friction and forging forces on the assembly.