Investigation of the material removal model for bonnet tool polishing with precession

Bonnet tool polishing is a novel aspherical polishing method. This paper describes a method to obtain the local removal rate for the polishing process by using bulbous flexible membrane covered with a polishing pad and pressurized by an internal fluid. During the polishing process, the precession process, in which the bonnet tool can not only spines itself, but also precesses along the local normal on the specimen surface, was applied. The local removal rate model was established according to the Preston Equation. The influence of the precession process on the material removal rate was analyzed, also the polishing pressure distribution was obtained according to the experiment data. It is confirmed by the experiments that the dwelling time has a linear relation with the local removal depth. Preston coefficient can be calculated from the experimental data. Finally the expression of the local removal rate in bonnet tool polishing was acquired experimentally.