SURFACE ROUGNESS IMPROVEMENT OF OPTICAL GLASS USING ABRASIVE JET POLISHING

Abstract

Surface finish plays an important role in product quality due to its direct effects on product appearance. Hence, improvement of the surface finish is an essential requirement in industrial products. In an attempt to improve the surface finish of N-BK7 optical glass material, some common methods have been used, such as grinding and lapping. However, the N-BK7 optical glass surface finish has not yet been significantly improved by using these methods. Therefore, this study proposes abrasive jet polishing (AJP) process that can considerably improve the N-NK7 optical glass surface finish. In addition, this study also takes into account optimal parameters for the AJP. Based on the Taguchi’s L18 orthogonal array experimental results and the signal-to-noise (S/N) ratio, the optimal parameters for the N-BK7 optical glass are found. These optimal parameters are to be as follows: a pressure of 5 kgf/cm2, an impact angle of 40°, a standoff distance of 12 mm, the abrasive material of Al2O3, an abrasive concentration of 20%, and a polishing time of 45 min. The surface roughness (Ra) of specimen is improved from 0.350 µm to 0.018 µm by using the optimal AJP parameters.

Keywords: Abrasive jet polishing, surface roughness, Taguchi method, ANOVA, optical glass