Material removal and tool path ripple error of bonnet polishing using pads with different groove patterns.

Bonnet polishing, which is a sub-aperture polishing method, is crucial to the production of aspherical lenses. However, sub-aperture polishing generates regular residual periodic ripples, which result in tool path ripple (TPR) error and reduce surface precision. This study investigated the effects of groove patterns in the heads used for bonnet polishing on material removal and the peak-to-valley (PV) and root-mean-square (RMS) error resulting from TPR. The effects of groove pattern (i.e., no groove, annular grooves, or radial grooves) on the tool influence function and TPR error were investigated through simulation and experimentation. Experimentally, the pad with annular grooves achieved the highest material removal rate, which was 56.3% and 14.0% higher on average than those achieved by the pads with no groove and radial grooves, respectively. However, the pad with radial grooves achieved the lowest PV (1.5834 nm) and RMS (0.7487 nm) TPR error, which were respectively 27.8% and 20.4% lower than those achieved by the pad with no groove and 43.3% and 46.0% lower than those achieved by the pad with annular grooves. In summary, annular grooves enhance material removal, and radial grooves improve surface quality. [ABSTRACT FROM AUTHOR]