Experimental investigation and numerical simulation of burr formation in micro-milling of polycarbonates

Abstract

Polycarbonates are naturally transparent amorphous polymers, used extensively nowadays to replace some of the applications of glass. Polycarbonates possess excellent impact and heat resistance, which made them suitable candidates for automotive, semiconductor, medical, household, and many industrial applications. Although polycarbonates are mostly formed by molding, further processing, especially machining of them still remains challenging. The objective of this study is to focus on an important issue during machining of polycarbonate, named burr formation. This study aims to identify the reasons and conditions behind the burr formation, and to investigate the effect of machining conditions, tool wear and tool coating on the amount of burr formation. In addition, the Finite Element Method (FEM) analysis using AdvantEdge software has been used to analyze the behavior of material and to investigate the burr formation during up-milling of polycarbonates. It was found that tool coating doesn't have a significant effect on burr formation, as both TiN and TiAlN coatings were found to be ineffective in the reduction of burrs. The burr formation, interestingly, was found to depend on the combination of depth of cut and feed rate, rather than a single parameter alone. It was found that the FEM modeling was able to predict the burr heights within 1.6% - 10.8% accuracy. To conclude, the selection of cutting parameters by identification of ductile regime is found to be the most effective way of controlling the burr formation and obtaining smooth surface finish in polycarbonate glass.