A novel functionally graded lapping and polishing method for the improvement of material removal uniformity

A novel functionally graded lapping and polishing plate (FG-LPP) is proposed in this paper to solve the nonuniform distribution of the material removal rate on the target surface by using the normal homogeneous lapping and polishing plate (H-LPP) according to the Preston equation. The working mechanism of the FG-LPP has been numerically investigated to analyze its edge and boundary effect on the distribution of contact stress in workpiece. It is found that the elastic graded layer can be made by dividing it into many rings with different Young's modulus on the lapping and polishing plate that could significantly reduce the boundary effect on the distribution of contact stress in workpiece, and by using the matching module the edge effect on the distribution of contact stress in workpiece could be eliminated as well. The mathematical model has also been developed to predict the distribution of the contact stress between the workpiece and FG-LPP by adding the compensation function to consider the effect of the strains in x and y direction on the stress in z direction, and this model has been validated both numerically and experimentally. It is found that by using the FG-LPP both of the material removal uniformity from the K9 glass and its resultant surface finish can be improved as compared with the traditional H-LPP.