In a conventional centrifugal disk finisher, the abrasive pieces and the object or objects to be finished are placed into a stationary containment vessel which encloses a spinning disk that substantially acts as the floor of the containment vessel. The spinning disk imparts centrifugal force to the abrasive pieces, which collect on the inner wall of the vessel, then eventually fall towards the spinning disk due to gravitational force. The object is finished, that is, polished, by contact with the abrasive pieces experiencing rotatory and gravitational forces.
A persistent difficulty in centrifugal disk finishers has been the design of the interface between the spinning disk and the stationary containment vessel. One source of this difficulty is that small abrasive pieces and abraded particles from the pieces and the object being finished become lodged in the interface between the spinning disk and the inner wall of the stationary containment vessel. Another source of this difficulty is that the material used at the interface wears out quickly due to friction so that the disk finisher requires frequent maintenance.
Various techniques have been used to address this difficulty in known centrifugal disk finishers, such as minimizing the size of the interface, that is, reducing the size of the gap between the spinning disk and the inner wall; using a disk having edges formed so as to direct the pieces and particles away from the interface; and forcing a fluid, such as water or air, into the interface so as to purge the particles and provide lubrication.
However, the technique of minimizing the size of the interface and the technique of using a disk with specially formed edges depend on the availability of precisely formed parts and the maintenance of a constant angular velocity during operation of the disk finisher. The technique of forcing a fluid into the interface depends on the availability of a high pressure, high volume fluid supply, and uses a gap of large size, which prevents both the finishing of small objects and the use of abrasive pieces cf small size. Additionally, the use of water as a fluid is sometimes undesirable.
Furthermore, all known disk finishers experience critical wear after a relatively short amount of use, such as 400 hours, and require replacement of the worn out portion or portions of the disk finisher.