Experimental Study on the Determinants of Surface Finish in Automated Polishing of Moulds

Abstract

Polishing of core and cavity surfaces after machining is a vital operation in the processing of plastic and metal cast products. It is carried out in order to achieve a certain degreeof surfacefinish-roughness or smoothness-on the machined surface, depending on its application as an end product and also for release from the cavities during ejection of the parts after moulding. Polishing is a high skilled manual time-consuming process in the overall cycle time of mould manufacturing. In this study, a CNC toolpath is generated in order to polish the core and cavity on the same machine where it is machined initially. The machine parameters for the polishing of the surfaces are optimized through a DOE set up. The surface finish achieved through machine polishing is inspected and recorded using a surface roughness tester and toolmaker’s microscope. It is observed, through the study that a combination of higher interference values between the tool face and the surface being polished along with higher feed rates proved to be determining factors in providing better surface finishes as high as 0.5μ Ra in machine polishing.