A cylindrical ring assembly centered at the node of the booster body. The clamp ring supports the stack in the welding stand and transmits the required welding force from the stand to the stack, while preventing the escape of acoustic energy from the stack to the stand.
The clamp ring is often isolated from the booster body by O-rings. In this case, the clamp rings usually have some means to prevent the rings from rotating about the booster body. Otherwise, the horn would not maintain proper rotational alignment to the part that is being welded.
In special cases, the clamp ring may be rigidly attached to the booster body in order to provide additional rigidity and accuracy. See rigid mount booster.
Also see nodal flange.