Investigation into material removal influenced by edge effect in polishing

Abstract

Edge effect is unavoidable in polishing process when the polishing pad passes by the workpiece edge, which influences the entire form accuracy of free-form surfaces of optical components in computer-controlled polishing, or even reduces their effective aperture. This article focuses on a theoretical and experimental investigation into the material removal influenced by edge effect for polishing along a certain path. The contact pressure distribution models for polishing the workpiece edge are summarized and modified into four representative models: linear model, skin model, linear skin model and divided skin model, which are adopted to calculate the theoretical material removal profiles orthogonal to the straight or curved polishing path, in this article. So, the material removal models are built in the process of polishing along tool path instead of polishing on a single point. And experiments are carried out to choose the most suitable contact pressure distribution model according to the comparison of experimental profiles and the different theoretical profiles. Experimental results reveal the influences of edge effect on material removal and a modified parameter is introduced into the theoretical material removal profile for the curved path to coincide with the experimental profile better. In addition, some qualitative analyses about how to reduce the edge effect are also given in this article.