Papers by Author: Su Juan Wang

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Authors: Chi Fai Cheung, Wing Bun Lee, Sandy To, H.F. Li, Su Juan Wang
Abstract: The fabrication of high-quality optical microstructural surfaces is based on fast tool servo (FTS) machining. It makes use of auxiliary piezo-electric driven servos to rapidly actuate the diamond tool with a fine resolution and a sufficiently high bandwidth for machining optical microstructures with submicrometer form accuracy and a nanometric surface finish without the need for any subsequent post processing. However, the achievement of a superior mirror finish and form accuracy still depends largely on the experience and skills of the machine operators, acquired through an expensive trial-and-error approach to using new materials, new mircostructural surface designs, or new machine tools. As a result, this paper, a model-based simulation system is presented for the optimization of surface quality in the FTS machining of optical microstructures. Preliminary experimental work and the results are also presented.
Authors: Sandy To, Chi Fai Cheung, Su Juan Wang, Wing Bun Lee
Abstract: Optical communication is gaining popularity in telecommunications; most obviously evident is the increase in demand for a large variety of fiber optic components. V-groove structure quality is critical to the functionality of the fiber connector as it governs the position of the optic fibers. The main parameters, which determine the V-groove quality, include core pitch, surface roughness and the position of centerline. In this paper, a series of cutting conditions were applied to investigate the effect of different machining parameters on the V-groove quality. In the experiment, the V-groove structure is machined by a 40° single crystal diamond tool on aluminium alloy with different cutting conditions. Based on the findings, the relationship between the cutting conditions on the surface roughness was explored. The implications of these findings on the improvement of the surface finish of V-groove profile are discussed.
Authors: Su Juan Wang, Suet To, Chi Fai Cheung, Wing Bun Lee
Abstract: Ultra-precision raster milling (UPRM) can directly achieve the fabrication of threedimensional non-axisymmetric freeform components with nanometeric surface finish and submicrometric form accuracy. During the past few years, a lot of research on computerized numerical control (CNC) machining technologies has been conducted; however, little of this research makes any contribution to UPRM. This paper studies the mechanism of scallop height generation for UPRM. Through analyzing the cutting edge locus and the scallop height generation mechanism, a model for feed-intervals and for raster-interval scallop height generation, are presented. Parameters such as selection of feed direction (vertical cutting and horizontal cutting), feed rate, spindle speed, tool nose radius, swing distance, feed length and raster distance have been taken into consideration in the scallop generation models.
Authors: Tsz Chun Kwok, Suet To, Chi Fai Cheung, Su Juan Wang, Wing Bun Lee
Abstract: Microlens arrays are widely used as critical components in a large number of photonics and telecommunication products. The increasing demand for high-tech products provides an expanding room for the development of the micro-fabrication technology. This study presents a tool compensation for correcting the form error of fabricated microlenses in ultra-precision machining with fast-tool-servo (FTS) system. After presentation of optimal cutting conditions deduced on the basis of cutting experiments of microlens arrays, a tool radius compensation method will be proposed and evaluated in this paper. This methodology makes use of form measurement data from a Form Talysurf system to modify the C program employed in the software of ultra-precision machining FTS system – SOP. The form error was successfully reduced after implementation of tool compensation.
Authors: Su Juan Wang, Chi Fai Cheung, Sandy To, Wing Bun Lee
Abstract: Recently, the high quality and high productivity in fabrication of freeform optics has been of primary interest in manufacturing industries, such as die and mould manufacturing, aerospace part manufacturing, and so forth. However, the fabrication of freeform optics is currently expensive and vastly complex. Ultra-precision raster milling can produce non-rotational symmetric surfaces with sub-micrometric form accuracy and nanometric surface finish without the need for any subsequent post polishing. While, there is little research work focus on this kind of machining method. This paper presents a framework of a tool path generation system for freeform surface ultra-precision raster milling. This system includes model of freeform optics, tool path generator, interference monitor and an optimization model of machining parameters. The tool path generation system can generate interference free and optimal tool path for machining freeform surfaces. Some simulation results have been presented to illustrate the performance of the system.
Authors: Suet To, Hao Wang, Bing Li, Chi Fai Cheung, Su Juan Wang
Abstract: Nowadays faceted reflector design has become popular in automotive illumination systems. The advantage of a compound surface enables it to achieve the required hot spot intensity by directing more than 60% of the generated light towards the road, thereby largely illuminate the area through the aperture. The research is oriented to fabricating the mold insert on ultra-precision raster milling (Freeform 705G). In this paper, the tool path generation method for automotive headlamp reflectors is studied, and a practical gouging detection and avoidance algorithm is proposed. The surface roughness and form accuracy (peak-to-valley height) are then calculated theoretically using mathematical formulae. Through the tool path generation of a small but representative surface patch with a gap, a possible way is finally found to generate the tool path for such a class of freeform surface with special equipment.
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