Design of an ultra-precision CNC chemical mechanical polishing machine and its implementation

Abstract

The chemical mechanical polishing (CMP) is a key process during the machining route of plane optics. To improve the polishing efficiency and accuracy, a new CMP model and machine tool were developed. Based on the Preston equation and the axial run-out error measurement results of the m circles on the tin plate, a CMP model that could simulate the material removal at any point on the workpiece was presented. An analysis of the model indicated that lower axial run-out error led lower material removal but better polishing efficiency and accuracy. Based on this conlusion, the new CMP machine was designed, and the ultra-precision gas hydrostatic guideway and rotary table as well as the Siemens 840Dsl numerical control system were incorporated in the new CMP machine. To verify the design principles of new machine, a series of detection and machining experiments were conducted. The LK-G5000 laser sensor was employed for detecting the straightness error of the gas hydrostatic guideway and the axial run-out error of the gas hydrostatic rotary table. A 300-mm-diameter optic was chosen for the surface profile machining experiments performed to determine the CMP efficiency and accuracy.