Materials Science Forum Vols. 532-533

Abstract: Double sided polishing process has become a main machining method for silicon wafer finishing process, but it is difficult to get ultra-smooth surface with the very stringent machining conditions. In this paper, the mechanism of ultra-smooth surface machining process was studied, the main parameters affecting the surface quality of silicon wafer, such as the polishing pad and carrier rotation speed, polishing press, polishing slurries etc. , were discussed and optimized, then ultra-smooth surface of silicon wafer with Ra 0.4nm has been obtained based on the above study. A new double sided polishing machine with computer control system equipped with a digital controlled press valve was developed, and the ultra-smooth machining process of silicon wafer was established in this paper.

Abstract: The magnetic coupling can availably solve the leakiness problems of machine equips. But there is a problem currently in the common synchronous magnetic coupling that the inner rotor magnet steel is demagnetized under high temperature. According to reverse design method, a kind of novel permanent induction magnetic coupling is researched. Its inner rotor is similar to that of asynchronous motor, and it does not need permanent magnet material. So it can be used in both normal and high temperature and is free from transporting medium temperature. Because of the variety of magnetic field, it is extremely complicated. Here the software ANSYS FEM is used to analyze it. Its main process can be divided into three steps: solution preprocess, solution process and solution postprocessing, thus the magnetic field strength value of every point of the coupling can be gotten, and it can be shown conspicuously with the sketches or charts. Then the power and torque also can be solved accordingly.

Abstract: Chemical vapor deposition (CVD) diamond coatings were deposited on cemented carbide cutting cools by an electron-assisted hot filament chemical vapor deposition (EACVD) equipment developed by the authors. The CVD diamond coatings were studied by Scanning Electron Microscope (SEM) and Raman Scattering Spectroscopy (Raman). The experimental results show that CH4 concentration in the source gas performs great influence on the micro-structure, surface roughness, composition, residual stress and adhesion of the CVD diamond coatings. The increase of CH4 concentration results the change of diamond crystal from {111} orientation to {100} orientation, the decrease of the surface roughness and the increase of sp2 carbon in the CVD diamond coatings. A residual compressive stress exists in the CVD diamond coatings. The residual stress decreases with increasing CH4 concentration. A higher or lower CH4 concentration tends to reduce adhesion stress of the continuous CVD diamond coatings.

Abstract: An experimental procedure was developed to separated the uncertain cutting forces generated by the minor cutting edges for interpreted the force components generated by the main and minor cutting edge. Cutting forces generated by minor cutting edges were investigated by experiments in precision hard part machining hardened GCr15 bearing steel with BZN8200 PCBN tool. With the improved chip loads, constitutive model and chip flow angle model, the predicted cutting forces show great agreement with the experimental results and verified the reliability of an improved cutting force model.

Abstract: The surface quality is a critical factor affecting the performance and reliability of advanced ceramics. This paper focuses on the application of Taguchi method for optimization of advanced ceramics lapping process parameters to obtain the best finish. An optimization experiment for lapping silicon wafer with Al2O3 was designed by Taguchi method. Surface roughness Ra and Rt are considered as criteria for optimization. Influence of parameters involving load, speed, and slurry concentration for a given workmaterial with given abrasive (material and size) are discussed, and the optimum lapping conditions are figured out. Compared with single parameter experimental results, it illustrates that the experiment design based on Taguchi method can successfully applied to determine the optimum processing conditions for advanced ceramics lapping process.

Abstract: Diamond Dressing Roller is a new kind of diamond tool for profile dressing of grinding wheel on form grinding. In this paper, internal electroplate method manufacturing process of high precision intricate diamond dressing roller is introduced. The tolerance of profiler precision degree of high precision intricate diamond dressing roller by this manufacturing process is less than 0.005mm.

Abstract: In the field of fault diagnosis for rotating machines, the conventional methods or the neural network based methods are mainly single symptom domain based methods, and the diagnosis accuracy of which is not always satisfactory. To improve the diagnosis accuracy a method that combines the multi-class support vector machines (MSVMs) outputs with the degree of importance of individual MSVMs based on fuzzy integral is presented. This provides a sound basis for integrating the results from MSVMs to get more accurate classification. The experimental results with the recognition problem of a blower machine show the performance of fault diagnosis can be improved.

Abstract: This work proposes a practical approach to generating NURBS tool paths by accurately fitting ideal paths. A two-stage fitting process is included in this approach. Since NURBS paths can make accurate, smooth sculpture surfaces, this approach can promote the use of these paths in the manufacturing industry.

Abstract: This paper presents a novel, rapid and damage-free method to polish the ultra-smooth surface of the SiC optics. First, the basic philosophy of this method is introduced, which uses the active radicals got from CF4 in the atmospheric pressure plasma zone to react with the SiC material at the optics surface to generate the vaporization of SiF4. Then, the design of the atmospheric pressure plasma jet and the corresponding prototyping polishing facility are introduced. The theoretical analysis on the necessary conditions to generate the excited radicals is also presented in this part. To verify the effectiveness of this novel polishing method, experiments on the generation of atmospheric pressure plasma and the SiC optics polishing are carried out with our prototyping facility. The experiment results show that plasma discharge is stable at the atmospheric pressure and sub-nanometer roughness of the polished SiC surface can be obtained.

Abstract: Circular arc flexible forming of sheet metal using plasma arc can be made by combing V-shape curving, the geometrical relationship between circular arc bending part and V-shape is investigated in this paper. In this thesis, the authors analyzed the relationship between a parameter γ and the degree of circular arc smoothness firstly. A simulation program was programmed using the FEA analysis software ANSYS, and the experiments were done. The results showing, when γ = 0.1
0.12, the forming circular arc is very smooth. The numerical simulation is right for the experimental results.