Comparative Analysis of Shape Defects Induced by the Micro-Machining of Glassy Polymers

This paper aims to investigate the cutting behavior of optical glassy polymers in order to identify the shape defects induced by the micro-machining processes. Polycarbonate (PC), Allyl Diglycol Carbonate (CR39), and polythiourethane (MR7) polymers are considered in this study to perform micro-machining experiments using the orthogonal cutting configuration. The comparative analysis is carried out by conducting the cutting experiments on hybrid samples that are composed of two types of polymers (MR7-PC, CR39-PC, and MR7-CR39) and then comparing the topographic state of the machined hybrid surfaces. Results show that PC is by far the polymer that generates the most shape defects because of its high rate of spring-back. This finding has been validated by nanoindentation experiments that reveal the highest mechanical reaction of PC at the time of nanoindentation unloading. This study demonstrates also that the measured thrust forces could be an indicator for predicting the spring-back defects induced by micro-machining.