Experimental investigations on ultra-precision machining of polycarbonate and related issues

Abstract

Optical plastic lenses are progressively substituting glass optics due to their lightweight and low costs. Polycarbonate (PC) is considered as one of the leading optical materials due to its good mechanical and optical properties. Ultra-precision machining is the most suited process to develop PC optical components. Nevertheless, ultra-precision machining is considered as one of the deterministic processes to ensure the surface quality required for optical components. However, it is important to understand the behavior of the material during each stage of manufacturing. PC offers many challenges during its processing to achieve the nanometric finish and sub-micron form accuracies. In this article, the various issues of PC machining are discussed through experimental investigations. The effect of machining variables, that is, machining parameters, cutting temperature, and vacuum clamping on surface quality is studied. The results show the importance of the selection of optimum conditions for machining PC with good surface quality. The PC optical component is developed with surface finish (Ra) 18.1 nm and profile accuracies (Pv) of 0.116 µm. The study is helpful to understand the various issues involved in PC machining and hence to minimize their effects on surface quality.