Multi-scale modeling and simulation of material removal characteristics in computer-controlled bonnet polishing

Computer-controlled Bonnet Polishing (CCBP) is an enabling technology which is capable of fabricating ultra-precision freeform surfaces with sub-micrometer form accuracy and surface roughness in the nanometer range, especially for difficult-to-machine and ferrous materials. However, the material removal mechanism of computer controlled bonnet polishing (CCBP) usually exhibits multidisciplinary and multi-scale complexity and hence our understanding of the material removal characteristics is still far from complete. As a result, this paper presents a multi-scale theoretical model for the prediction and simulation of the material removal characteristics in the CCBP process. The model is established based on the study of contact mechanics, kinematics theory and wear mechanisms. A series of spot polishing tests as well as simulation experiments by the theoretical model were conducted. The predicted results agree well with the experimental data. The successful development of the theoretical model helps to make the CCBP process more predictive, and so that optimizing the manufacturing process, and forms the theoretical basis for explaining some material removal mechanisms in CCUP, such as the critical polishing depth for minimizing pad scratching.