Influence of motion modes on surface quality in CCOS

One of the important factors that affect the polishing results is the motion modes of the polishing pad in the process of Computer Controlled Optical Surfacing (CCOS). This paper presents a systematic study for the motion modes in CCOS by using a polishing pad. A series of theoretical and experimental studies have been undertaken to investigate the influences of two typical motion modes, called planet motion and orbital motion, on the polished surface, regarding to material removal rate (MRR), middle-spatial-frequency errors, surface roughness, etc. Firstly, the theoretical removal function of the two motion modes was established, and the experiments were carried out by given polishing parameters. A comparison was made between the results of experiments and simulations by the established polishing model. Then, the effects of the mentioned two motion modes on middle-spatial-frequency errors were simulated by the numerical superposition method, and the results were also verified by actual polishing results. Finally, the surface roughness generated by the two different motion modes was examined and compared. The research work shows that the planet motion has higher material removal rate, lower middle-spatial-frequency errors and lower surface roughness, by compared with orbital motion mode, which is helpful for optimizing the polishing strategy during CCOS.