Advanced Materials Research Vol. 797

Abstract: In order to solve the problem of the randomly arrangement of the diamond abrasives, a novel orderly arrangement grinding wheel was developed, which used magnetic field to control the magnetic particles to drive diamond abrasives orderly arrangement. Effects of magnetic flux density on magnetic particle distribution was studied. And effects of magnetic particle proportion on magnetic particle distribution was studied. Grinding experiments were carried out on the tungsten carbide YG8 and surface roughness after grinding was also analyzed.

Abstract: The machining quality of rolling bearing raceway has an important impact on bearing life. In this paper, the finishing experiment equipment of rolling bearing raceway is built and the mechanical and electrochemical mechanical experiments are conducted. The impact of clearance between cathode and workpiece, the rotation speed and the abrasive grain size on electrochemical mechanical machining quality is analyzed. The surface roughness decreases from Ra0.20μm to Ra0.04μm through electrochemical mechanical machining. The surface morphology of workpiece after finishing is observed. Contrast with the surface morphology after conventional mechanical polishing, the surface after electrochemical mechanical finishing is more suitable to the bearing raceway.

Abstract: In recent years, developments in the semiconductor and electronic industries have brought a rapid increase in the use of large size silicon. However, for many companies, it is hard to produce 400mm or 450mm wafers, because of excesive funds for exchange the equipments. Therefore, it is necessary to investigate 300mm wafer to obtain a better efficiency and a good property rate. Wafer final Polishing is one of the important methods in manufacturing of Si wafers and in thinning of completed device wafers. This research investigated the surface characteristics and optimum condition of applied pressure, polishing speed and slurry-mixed ratio to achieve the optimum condition of wafer final polishing by Taguchi method. By using optimum condition, it helps to achive an ultra precision mirror like surface.

Abstract: This paper represents a dual-plane polishing method for ceramics ball. Compared with traditional ball polishing method, its upper and lower plate are all flat and easy to use soft pad to polish, so it can largely reduce the surface mechanical damage and obtain high quality processing surface. This paper analyzes surface polishing trajectory by calculation and simulation to test the polishing trajectory uniformity. A mathematics model of polishing process is established to disintegrate the process of a balls movement. Experiment is operated in dual-plane planetary polishing machine. The result shows that perfect polishing surface and spherical error can be obtained under the proper process parameters, the surface roughness achieves 4nm and the spherical error can reach 0.217μm.

Abstract: Demands of precision molds with complicated microstructures for digital devices such as DVD pick-up system, and medical devices such as μ-TAS and solar optics etc. are increasing. To enhance precision, the structured molds must be polished after grinding or cutting in order to improve the surface roughness. In this paper, a two-dimensional low frequency vibration (LFV) polishing actuator using PZT is proposed and developed. The LFV consists of four mechanical amplitude magnified actuators, a multilayer stacked piezoelectric actuator (PZT) incorporated with mechanical transformer, and a center piece. In the polishing experiments, HIPM workpieces were polished with WA slurry by the rotation & revolution type polishing method (RRP). The surface roughness of the work pieces and material removal amount (polished amount) was also evaluated. From the experimental results, it was found that the application of low frequency vibration is useful for realizing higher precision in the polishing of micro structured molds.

Abstract: Our main purposes were to establish ultraviolet-ray aided machining (here after reffered to as U-RAM) and clarify the chemical and mechanical polishing mechanism. The inner/outer surfaces of small cup-type nickel tube is strongly required to polish, simultaneously. The present study deals with the new development of simultaneous polishing technology and the verify of polishing phenomena that uses a photocatalyst and a cathilon (a luminous dye: Cathilon Brilliant Flavine; hereafter referred to as cathilon) excited by an ultraviolet ray (hereafter referred to as UV). Measurements and observations clarified that TiO₂ of 0.18-μm grain size polished chemically/mechanically the outer surface using cathilon, and cathilon chemically polished the inner surface of small cup-type nickel tube, simultaneously. Further measurements indicated that the chemical erosion roughened the inner surface, when cathilon increased from 2.5, 5 to 20wt%. An increase of TiO₂ to 20wt% at 20wt% of cathilon did not result the flatter surface. Aluminum oxide does not provide the polishing ability due to the poor photocatalyst effect compared with TiO₂.

Abstract: This paper is to design and developing a friction sensor system (FSS) for prediction of endpoint detection (EPD) on diamond lapping of sapphire or mono-crystalline aluminum oxide wafers. The endpoint detection usually includes start region, lapping region, transient region and endpoint region to control the planarization procedure by diamond lapping with variant plate of copper, resin copper, or tin materials. Experiments have been performed with 9 tests composed by three kinds of viscosity of slurry lapping with three kinds of lap plates. The coefficient of friction (CoF) has been obtained by the designed FSS and then compared with different test parameters. The as-lapped sapphire wafers have also measured by coherence surface interferometer, CCI-Lite (Taylor Hobson, UK). Experimental results show that the hardness of plate and viscosity of slurry are critical factors for as-lapped wafer quality. The EPD of diamond lapping with resin copper plate can be determined by the CoF data and that can be used for justifying the appropriate lapping time of sapphire wafers. Future study can focus on the relationship of sub-surface crack caused by the diamond lapping process.

Abstract: In order to solve the problem about polishing complex cavity of precision mold, to improve the efficiency of processing and reduce the surface roughness, putting forward multiple entries impinging stream processing device.With making use of the collision of two strands of abrasive flow, Realizing the mutual disturbance of abrasive flow in the runner, and increasing the collision between abrasive to improve the disordering of abrasive movement, for promoting abrasive polishing to mold cavity. Johnson-Cook elastic-plastic material model is set up at the same time, using abaqus finite element simulation to simulate the impact deformation wear and cutting wear with the increasment of impact times.

Abstract: In this study, the novel finishing method of the Micro Lens Array mold is proposed. This method combines the cutting by a ball-endmill and the finishing by sphere indentation. In the previous step, U-shape grooves intersected at right angle are machined by a ball-endmill. In the following step, the ball tool indents at the intersection between U-shape grooves, consequently, the aiming lens form and the aiming surface roughness are obtained. From the results of the manufacturing experiments of the MLA mold by this method, the following are made clear : The proposed method is effective to suppress the deformation of neighboring lens forms caused by following indentation. The improvement effect of sphere indentation on the finished surface roughness is remarkable in the early stage of indentation. The transcribing deviations are 12μm or less in comparison between the radius of lens form and the ideal value regardless of radii in grooves previously cut. In case of the indentation of neighboring four (2 × 2) lenses, the deviation reduces down to 3μm.

Abstract: This paper aims at increasing the forming accuracy of microgrooves by using electroless plated Nickel Phosphorus (Ni-P) as the mold material in glass molding press (GMP) process. The mechanical characteristics and the performance of amorphous Nickel Phosphorus (a-Ni-P) plating layer were experimentally tested. In order to bring down the deformation of the a-Ni-P mold and increase the forming accuracy of microgroove molding, polycrystalline Nickel Phosphorus (c-Ni-P) was developed by heat treatment. With the increase of the hardness after crystallization, the plating layer shape changes due to the heat treatment, and the strategy to deal with the deformation and the techniques to produce c-Ni-P mold are generalized. Finally, the performance of c-Ni-P mold was experimentally tested, which confirms that c-Ni-P is an excellent mold material for glass microgroove forming.