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.

Deterministic polishing of freeform optical surface by iterative intersection tool path in an off-axial three-mirror anastigmat imaging system

“…The normal force, rotation speed of polishing tool and other parameters except the feed speed are regarded as constant. Therefore, equation (14) can be represented as…”

“…But the polishing efficiency is not considered sufficiently in this article. Several contact pressure distribution models are compared in edge polishing by Zhou et al, 14 and a more accurate equation of material removal is presented. The influence factors of edge effect are also analyzed, but the defect in edge area cannot be eliminated.…”

Effect of material removal state on the selection of theoretical models when scratching single-crystal copper using the load modulation approach

“…However, when conducting scratching process with different directions, the machined depth shows different values, and the material removal state is also related to the combination of the geometry and the machining direction. [24][25][26][27] Thus, in our previous study, 28 the theoretical model is established by considering the tip geometry as a three-sided pyramidal with a spherical apex. Different material removal states have a large influence on the probe-sample contact area, which is the critical value in the theoretical model.…”

Modeling and optimization of material removal influenced by sliding velocity in polishing

“…14 However, the orbital motion of the polishing pad would lead to a relatively large processing area, thus the edge effect during the polishing, which refers to the nonlinear removal behavior as the tool runs over the edge of the part surface, is severe. 15 As a result, the orbital motion is only suitable to fabricate the large part surfaces. The polishing of the small surface components usually employs a rotational spindle at a specific angular velocity with a small spherical tool.…”