Papers by Keyword: Single Point Diamond Turning

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Authors: Ming Chu Kong, Wing Bun Lee, Chi Fai Cheung, Suet To
Abstract: The formation of tool marks in single-point diamond turning is a fundamental study of the effect of materials swelling and recovery on surface roughness on a machined surface. A series of orthogonal face cutting tests has been conducted among plate aluminum alloy, oxygen-free high conductivity copper and electroless nickel phosphorus under the same cutting conditions by the use of facet tools with different front clearance angles. The results show that the regular width of the undulating pattern in tool marks could be explained by side swelling and the micro-waviness within a tool mark is caused by burnishing and recovery.
Authors: Xiao Dan Xie, Yong Li, Cam Vinh Duong, Ahmed Al-Zahrani
Abstract: Traditionally, single point diamond turning (SPDT) can not process ferreous metals because of acute tool wear. Ultrasonic vibration-assisted cutting(UVC) provides a promising solution for the problem. In this paper, for the aim of directly obtaining mirror surface on die steels, UVC method was used combining with SPDT process. Experiments were carried out on an ultra precision turning machine, cutting parameters and vibration parameters were well-chosen, and two kind of feed rates, two kinds of prevailing die steels were experimented. Mirror surfaces were successfully achieved on face turning, with the best roughness of Ra16.6nm. And the surface roughness, surface texture and tool wear in machining process were discussed.
Authors: Jae Young Joo, Chang Suk Kang, Soon Sub Park, Sun Kyu Lee
Abstract: In this paper, we demonstrated the machining process of a novel Light Emitting Diodes (LED) beam shaping lens, called TIR Fresnel lens, for GaN-based blue Chip Scale Packaged (CSP) LEDs. Upon achieving a precise alignment of the tool and identifying the best manufacturing condition, we have successfully fabricated a prototype of this lens on poly methyl methacrylate (PMMA) plate. The form error of the central aspheric lens was less than 1 μm deviation, and surface quality of the Fresnel facets were sufficient for Total Internal refraction without any burr or adhesion of the machined chip. Fabricated TIR Fresnel lens reduced the viewing angle of the testing CSP LED from 140° to 17.4° in FWHM. The proposed lens produced extreme compactness as well as high collimation efficiency, thereby applicable to an ultra-thin optical system.
Authors: Wing Bun Lee, Chi Fai Cheung, Suet To
Abstract: A multi-scale model is proposed to explain the effect of material induced vibration and the quantitative relation between cutting force and the surface quality from dislocations, grain orientations, cutting tools, machine tools used in the simulation of the nano-3D surface topology in single-point diamond turning. The model-based simulation system composes of several model elements which include a microplasticity model, a dynamic model and an enhanced surface topography model. The multi-scale model brings together knowledge from various disciplines to link up physical phenomenon occurring at different length scales to explain successfully the surface generation in single-point diamond turning of crystalline materials, and offers a new direction of research in ultra-precision machining.
Authors: Chi Fai Cheung, Wing Bun Lee, Suet To, Ling Bao Kong
Abstract: One of the remarkable achievements of nanotechnology is the ability to achieve nanometric surface finishes in single-point diamond turning of high-precision components for complex optical surfaces. A better understanding of the surface generation mechanisms is of prime importance for the development for the prediction of the surface roughness. This paper presents a study of mechanisms of nano-surface generation in single-point diamond turning of various types of materials.
Authors: Saurav Goel, Xi Chun Luo, R.L. Reuben, Waleed Bin Rashid, Ji Ning Sun
Abstract: Wear of diamond tool has always been a limiting factor in ductile regime machining of large size silicon components. In order to understand the tool wear phenomena, it is non-trivial to know the process outputs especially cutting forces, stresses and temperature during nanometric turning. In this paper, a realistic potential energy function has been deployed through molecular dynamic (MD) simulation, to simulate the process outputs of single diamond turning operation against single crystal silicon. The simulation result suggests that wear mechanism of diamond tool is fundamentally governed by these process parameters and thus critical.
Authors: Saurav Goel, Xi Chun Luo, R.L. Reuben, Waleed Bin Rashid, Ji Ning Sun
Abstract: Silicon carbide can meet the additional requirements of operation in hostile environments where conventional silicon-based electronics (limited to 623K) cannot function. However, being recent in nature, significant study is required to understand the various machining properties of silicon carbide as a work material. In this paper, a molecular dynamic (MD) simulation has been adopted, to simulate single crystal β-silicon carbide (cubic) in an ultra precision machining process known as single point diamond turning (SPDT). β-silicon carbide (cubic), similar to other materials, can also be machined in ductile regime. It was found that a high magnitude of compression in the cutting zone causes a sp3- sp2 order-disorder transition which appears to be fundamental cause of wear of diamond tool during the SPDT process.
Authors: Choung Lii Chao, Chun Chieh Chen, Chia Jong Chang, Han Shan Dong, Kung Jeng Ma, Wei Yao Hsu, Kuo Cheng Huang, Chung Woei Chao
Abstract: Stainless steel and other ferrous metals are normally classified as not diamond turnable for the unacceptable tool wear caused by the thermal-chemical reaction between diamond and ferrous metals. In the present research, stainless steel specimens were plasma nitrided at a relatively low temperature (<450oC) to prevent the depletion of Cr content at the austenite matrix and to give a hardened layer where Fe atoms are bonded to nitrogen atom to form γ’-Fe4N. Diamond turning experiments were subsequently carried out under the following machining conditions: single crystal diamond tool, cutting speed up to 180 m/min, cut depth up to 5μm and light mineral oil as the cutting fluid. The results showed that, given the same machining conditions, while rapid tool wear and poor surface finish were obtained when turning the as-received stainless steel, surfaces with Ra better than 3nm and no obvious tool wear were achieved when turning the plasma nitrided specimens
Authors: Hong Hui Yao, Tao Sun, Zeng Qiang Li
Abstract: In the respect of ultra-precision manufacturing of axisymmetric surface, the machine tool with tool swing feeding has less interpolation error sources compared to the conventional ultra-precision diamond turning machine tool. The installation errors of machine tool greatly affect the manufacturing accuracy of parts. Therefore, based on the multi-body dynamics theory , the structure characteristics of this machine tool, and the parts' relative positions of machine tool, in this paper we established the space geometric model and the integrated error model of machine tool integrated with the actual installation error of machine. The analysis results of the error model show that the relationship between the depth of axis (tool shaft and main shaft of machine) parallelism and the profile error is linear function; when the installation error of swing arm was lower than 150′′,the profile error of parts was less than λ/10.
Authors: Jian Guang Li, Wing Bun Lee, Chi Fai Cheung, Sandy To, J.J. Du, Z.Q. Yin
Abstract: Virtual manufacturing (VM), which primarily aimed at reducing the lead times to market and costs associated with new product development, offers various test-beds for the time-consuming and expensive physical experimentation. Since surface roughness and form accuracy play essential roles in the functional performance of the products machined with ultra-precision machining technology. An optimizer, VSPDT (virtual single point diamond turning) system was developed for the purpose of form error compensation and optimal cutting parameters selection. In this paper, the keys issues for developing VSPDT using virtual manufacturing technology were highlighted such as framework of system, virtual workpiece, virtual machining and inspection, etc. At the end of the paper, A VSPDT was developed and applied to predict and compensate the form error, select optimal cutting parameters by using a 2-axis CNC ultra-precision turning machine.
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