Surface Roughness in Ultra-High Precision Diamond Turning of Silicone Hydrogel Contact Lenses

Abstract

The research work presented in this paper highlights the use of the process of ultra-high precision diamond turning when machining advanced contact lens polymers. The study is focused on investigating the effect of diamond cutting conditions on the surface quality of the polymers machined. A silicone hydrogel (Definitive 74) was used in this study. The surface roughness measurements were taken using a surface 3D profilometer. Response surface methodology techniques were employed to create predictive models for surface roughness with respect to the cutting speed, feed rate and depth of cut. The predictive surface roughness models were successfully generated for the polymer and the cutting speed and feed rate were identified as the most influential parameters on surface roughness.