The weld is made by rotating one component against a fixed component under pressure.

This action generates sufficient frictional heat for at least one of the materials to become plastic at the joint interface. At this point, rotation is stopped rapidly and the components forged together.

The result is a highly effective bond over the whole joint area, without melting the materials.

Rotation speed, friction time, friction and forge pressures and length-loss must all be carefully controlled. These are the basic process parameters, variable for different components and materials. Generally, at least one component must be circular at the joint face.