S. To

A multi-perspective knowledge-based system for customer service management

Abstract The e-business arena is a dynamic, complex and demanding environment. It is essential to make optimal reuse of knowledge of customer services across various functional units of the enterprise. On the other hand, it is also important to ensure that the customer service staff can access and be trained up with dynamically updated knowledge that meets the changing business environment of an enterprise in customer services. However, conventional way of customer service management (CSM) is inadequate to achieve the multi-perspective of an enterprise for achieving knowledge acquisition, knowledge diffusion, business automation and business performance measurement so as to drive the continuous improvement of the customer service quality. In this paper, a multi-perspective knowledge-based system (MPKBS) is proposed for CSM. The MPKBS incorporates various artificial intelligence technologies such as case-based reasoning (CBR) and adaptive time-series model which are used for decision analysis, performance measurement and monitoring. A prototype customer service portal has been built based on the MPKBS and implemented successfully in a consultancy business.

Effect of reinforcement in ultra-precision machining of Al6061/SiC metal matrix composites

Abstract The effect of reinforcement on surface generation in diamond turning of Al/SiC metal matrix composites is investigated. The surface generation is affected by the cut through and pulled out mechanisms in cutting the reinforcement. Better surface finish can be achieved with the use of whisker reinforcement and smaller volume fraction of SiC reinforcement.

A theoretical and experimental investigation of surface generation in diamond turning of an Al6061/SiCp metal matrix composite

Abstract In this paper, the surface generation in ultra-precision diamond turning of Al6061/15SiCp metal-matrix composites was investigated based on different analytical approaches which include parametric analysis, cutting mechanic analysis, finite element method (FEM) analysis and power spectrum analysis. Parametric analysis was performed to explore the in situ inter-relationships between the process parameters and the surface roughness. The surface properties of the diamond turned surface were extracted and analyzed by the power spectrum analysis of the surface roughness profiles. Different surface generation mechanisms were deduced based on the cutting mechanics and FEM analysis. The results of the theoretical analyses were verified through a series of cutting tests conducted under various cutting conditions and a good correlation between the theoretical and experimental results was obtained.

A Microplasticity Analysis of Micro-Cutting Force Variation in Ultra-Precision Diamond Turning

This paper describes a microplasticity model for analyzing the variation of cutting force in ultra-precision diamond turning. The model takes into account the effect of material anisotropy due to the changing crystallographic orientation of workpieces being cut. A spectrum analysis technique is deployed to extract the features of the cutting force patterns. The model has been verified through a series of cutting experiments conducted on aluminum single crystals with different crystallographic cutting planes. The results indicate that the model can predict well the patterns of the cutting force variation. It is also found that there exists a fundamental cyclic frequency of variation of cutting force per revolution of the workpiece. Such a frequency is shown to be closely related to the crystallographic orientation of the materials being cut. The successful development of the microplasticity model provides a quantitative means for explaining periodic fluctuation of micro-cutting force in diamond turning of crystalline materials.

Materials induced vibration in ultra-precision machining

Abstract In this paper, the development of a microplasticity model for predicting the effect of crystallographic orientation on the shear angle and the chip formation, as well as on the variation of micro-cutting force are discussed. The model forms a basis for the study of material induced vibration phenomenon encountered in ultra-precision machining. Material induced vibration has its origin in the variation of micro-cutting force caused by the changing crystallography of the material substrate being cut. It is a kind of self-excited vibration which is difficult to eliminate solely by machine tool design or process control. The magnitude of such vibration inevitably affects the surface topography of the workpieces in ultra-precision machining, and this sets a limit on the performance of an ultra-precision machine. A framework of a model-based simulation system is proposed to determine quantitatively the magnitude of the vibration and its effect on the surface topography of a diamond-turned surface. Features predicted from the system are found to correlate well with experimental findings.

Ageing characteristics of cast Zn-Al based alloy (ZnAl7Cu3)

Microstructure and ageing characteristics of a cast Zn-Al based alloy (ZnAl7Cu3) were studied using X-ray diffraction, electron scanning microscopy and back-scattered diffraction techniques. Two stages of phase transformation, i.e., decomposition of zinc rich η phase and four phase transformation, α + ε → T′ + η, were detected during ageing at 150°C. Electron back-scattered diffraction technique was applied in distinguishing both zinc rich η and ε phases.

Friction-induced fluctuation of cutting forces in the diamond turning of aluminium single crystals

Abstract This paper presents a multidisciplinary approach to the analysis of the fluctuation of cutting forces in the diamond turning of crystalline materials. The analysis is based on a microplasticity model for shear angle prediction and a cutting force model incorporating a friction variable which is estimated from the power spectrum analysis. The results reveal that the pattern of periodic fluctuation of the microcutting forces is not only due to the crystallographic orientation of the materials being cut but also to the friction between the chip and the tool face. The frictional effect is found to cause a change in the pattern and the periodicity of the fluctuation of the cutting force. The power spectrum predicted from the cutting force model incorporates a friction variable which can be chosen to match the experimental power spectrum, thus providing a new way to assess the frictional condition, and can be used as a diagnostic tool to monitor the tool wear and cutting conditions during diamond turning.

Molecular Dynamics Simulation for Ultrafine Machining

This article surveys the advances of molecular dynamics (MD) simulation in the research of ultrafine machining and related technologies. Modeling methods, including interatomic potentials and boundary conditions, are addressed. Algorithm strategies for MD simulations are discussed. By applying simulations with Tersoff potential, a case study of the material removal mechanism of the polishing based on coupling vibrations of liquid (PCVL) is presented.

Use of EBSD to study stress induced microstructural changes in Zn-Al based alloy

Abstract Tensile stress induced microstructural changes in an eutectoid Zn–Al based alloy were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD) techniques. Both Zn-rich η ′ T and e phases were identified by EBSD using predetermined lattice parameters of the phases. It was found that tensile deformation resulted in decomposition of the Zn-rich η ′ T and e phases in the furnace cooled (FC) eutectoid Zn–Al based alloy. With increasing strain, the decomposition of the η ′ T and e phases developed in the high stress concentrated neck zone and the rupture part of the FC-tensile deformed specimen. The measured preferred crystal orientations of the Zn-rich phases in the FC-tensile deformed Zn–Al alloy were in a good agreement with previous XRD investigation.

Ultra-precision machining induced surface structural changes of Zn–Al alloy

Abstract Ultra-precision machining was carried out on a furnace cooled (FC) eutectoid Zn–Al alloy specimen using a new technology of single point diamond turning (SPDT). Microstructural changes and phase decomposition at the surface of the ultra-precision machined alloy specimen were investigated. It was found that the ultra-precision machining induced external stress resulted in decomposition of the e phase and crystal orientation changes of the Zn-rich phases: η and e , at the surface of the machined FC Zn–Al alloy specimen, which were in agreement with the tensile stress induced phase transformations and crystal orientation changes in the FC Zn–Al alloy specimen.