Advanced Materials Research Vols. 102-104

Abstract: A three-dimensional hydrodynamic lubrication model for chemical-mechanical polishing is presented based on the Reynolds equation and Reynolds boundary condition. By solving the Reynolds equation, the slurry film pressure distribution has been obtained. The effects of minimum film thickness and the wafer tile angle on the film pressure are analyzed, and the influence of the polishing applied load and rotation speed on slurry film thickness and tilt angle are discussed. At last, by experiment, it is found that the simulation results are similar to experiment results which film thickness is increasing with the increasing of rotation speed, decreasing of the applied load. It is proved that the simulation is reliable.

Abstract: The present work focuses on the numerical prediction of the manufacture quality of a sliding panel structure, in which the mobile components are floating on the immobile components and the 0.002mm thickness oil-film clearance between the mobile and immobile components. The interaction between them is the interfacial coupling interaction. A single-point spring-damping supporting element is introduced to simulate this type of interaction traditionally, in which the torsion of the mobile components is increasing with the supporting element reduced. To analogy the interfacial coupling interaction, the finite centrality supporting method is introduced to study the thin oil-film effect between the mobile and immobile components. And the manufacturing quality is predicting through the numerical study. Compared with the results derived from the numerical and experiments, the manufacturing error is in accordance with each other.

Abstract: The efficiency of CNC machining is greatly influenced by the tool path. A new hybrid algorithm for tool path optimization in CNC varied-shape grinding is presented in this paper. The algorithm was constructed by adding hill-climbing algorithm to nature genetic algorithm. In the new algorithm, the crossover operator and mutation operator were redesigned to enhance the local search capability and to accelerate convergence. Verification experiment demonstrated that the algorithm can reduce non-cutting movement of tool paths and improve machining efficiency significantly.

Abstract: In ultra-precision cutting, grinding and non-traditional machining, it is difficult to balance long travel and high precision, especially in multi-coordinate machining. Aiming at tri-coordinate ultra precision machining, this paper studies the ultra precision machining technology and theory. It attempts to seek the principle in ultra precision machining as well as construct a pilot antitype with the ultra precision tri-coordinate machining system machine.

Abstract: Application of magnetic abrasive to the field of finishing processes is increasingly popular and important. Magnetic abrasive finishing (MAF) is effective in precision machining of non-planar workpieces. To study the control of working abrasive morphology and the valid way to solve “incline effect” which is common in some industrial field, application of magnetic abrasive in gasbag polishing is presented. Besides, the polishing system is introduced, and the important factors which influence the magnetic abrasive polishing are studied. Then some tentative experiments are carried out to study its polishing effect. It is found that the difference of surface roughness value and material removal rate under different bevel angle is in small range, which indicates this approach is useful in solving “incline effect”. The work in this paper is also a good attempt for further study that polish precipitous surface of mould or other products.

Abstract: This paper discussed the polishing characteristic of single crystal sapphire (0001) when using 100°C vapor as polishing liquid and cedar wood as polishing pad. Surface roughness and scratch were compared before and after hydration polishing process. For 20 hours hydration polishing, both XRD and surface texture show that sapphire surface was changed in micro-structure and texture, even with minor scratch on the hydration polished surface, surface roughness could be decreased to Rt6.74 in X direction and Rt7.64nm in Y direction, it is about 2 nm surface layer was removed during hydration polishing.

Abstract: High speed milling cutter is a representative cutter for high efficiency cutting, there is the indeterminacy induced by small sample and lacking information in evaluating its performance. By the analysis of cutter characteristics, acquires the data of structure, material and cutting parameter affecting the performance of cutter, and constructs structural levels model of performance behavior in designing cutter. Using the theory of axiomatic design, investigates mapping approach among structural domain, material domain and functional domain, and propounds collaborative design method of multilevel high speed milling cutter. Results of performance analysis and high speed milling experiment show that the model indicates the interaction among structural levels of cutter, and the design method makes the performance of cutter satisfy the requirements of safety, stability and high efficiency cutting.

Abstract: Nowadays NC cutting processing has become one of the basic methods of machine manufacture. However, the single precision has failed to meet the demand for the modern manufacture. The surface roughness, tools wear and material removal ratio are used as the objective to research, the orthogonal experiment is built by the Taguchi methods, and the fuzzy analysis is adopted to set up semantic rules between turning parameter and the objects. Then the Taguchi method is used to obtain the optical turning parameter. The QTN200M-500U NC turning center is used to carry out the turning experiment; Results from the experiments could be used as the references for future manufacturing designs.

Abstract: It is important of the rapid manufacturing for metal function part in RP/M field at present. A novel LOM technology based on the large thickness slice and CNC machine tool is proposed, which can improve the precision and intensity for the metal function part. Under the certain precision condition, the thickness of each layer is raised maximally by the novel LOM technology. The contour machining of metal slice is performed with CNC machine tool, and the connection of metal slices is accomplished with both vacuum solid pressure heat diffusion weld and assembling metal slices; The metal function part that has higher precision and strength is obtained finally by taking these measures.

Abstract: The fast development of SAW requests higher quality surface of CVD diamond films. Nowadays the mechanical lapping method is one important way to polish CVD diamond films, but the processing cost is high due to the low machining quality and efficiency. This paper reports a new accelerant lapping technology base on mechanical lapping and exploratory studies the role of three kinds of metal of the iron, titanium and nickel in the process of lapping. Firstly, ANSYS/LS_DYNA was used to simulate the process of friction and cutting between the CVD diamond films and abrasive plate of different material to analyze the temperature distributing on the interface and weather it is helpful for lapping. Then, experiment researches were carried out using the abrasive plate with different accelerant materials ratio. The results indicate that titanium is the most potent accelerant for polishing, followed by iron and then nickel. Experimental study also found that the accelerant lapping can carried out effectively by using the abrasive plate made of different metallic materials as accelerant to the diamond film grinding.