Papers by Author: Joseph A. Arsecularatne

Abstract: High speed machining (HSM) is finding wider applications due to its economic advantages, such as faster material removal rates, and its technological merits, such as improved surface finish. Nevertheless, the application of HSM also brings about some undesirable results. For example, the tool life and surface integrity of a machined component are greatly affected by the large amount of heat generated, but heat dissipation during an HSM has not been well understood. This paper aims to achieve a quantitative understanding of the heat dissipation in HSM using a bar turning configuration. Based on the calorimetric method and utilizing water as the heat transfer medium, the temperature rise in water was measured to determine the fractions of heat dissipated into the chips, the tool and the workpiece during machining. The obtained results show that the chips take the largest portion of the heat generated and this fraction increases with the increase in feed.

Abstract: This paper discusses the temperature characterization for nano-polishing of polycrystalline diamond composites (PCDCs) by combined experimental and theoretical modelling. It was found that a higher polishing pressure-speed combination results in a higher temperature rise and material removal rate. To optimize the nano-polishing of PCDCs and achieve a surface roughness of Ra = 50 nm, the interface temperature at polishing needs to be maintained at an appropriate level.

Abstract: This paper presents a cost-effective technique for achieving optical surface finish of thermally stable polycrystalline diamond (PCD) composites using dynamic friction polishing (DFP). The effect of polishing parameters on the material removal rate and surface characteristics of polished specimens were studied. The surface characterisation was carried out by optical microscopy, atomic force microscopy (AFM), scanning electron microscope (SEM) and its attached energy dispersive X-ray (EDX) analysis. It was found that optical surface finish of PCD with roughness Ra = 50 nm could be obtained efficiently with nearly a ten fold reduction in polishing time compared to the currently used method in industry.

Abstract: Micro-indentation has been widely used to evaluate the mechanical properties of materials. It has also been considered to be an important measure in the study of machinability of difficult-to-machine materials such as metal matrix composites (MMCs). Because of the complexity of deformation of an MMC and the interaction in the vicinity of contact zone between the indenter and work material, an analytical or experimental method is unable to predict the detailed deformation process. The present paper uses the finite element method to investigate the behavior of MMCs subjected to micro-indentation by a spherical indenter including the development of stress and strain fields in the MMCs during loading/unloading. Particle fracture, debonding and displacement, and inhomogeneous deformation of matrix material were explored and compared with the experimental results reported in the literature. The analysis also provides an insight for understanding the formation of residual stresses in machined MMC components.