Advances in Abrasive Technology IX

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Authors: Cheng Zu Ren, X.J. Guo, Li Wei Yuan
Abstract: In the paper, the Molecular Dynamics (MD) simulation model and the Finite Element (FE) analysis model were combined together to study the mechanism of the Electrolytic In-process Dressing (ELID) grinding. A 3-D MD simulation model for grinding monocrystalline silicon was established to acquire grinding force and its change laws, and an interpolation multinomial of grinding force was established on the basis of MD simulation result. A FE model for abrasives and the passivation film was established to calculate displacement of abrasives in the passivation film. The grinding force and abrasives displacement were iterated between MD simulation model and FE analysis model to obtain the displacement variation of the abrasives in the passivation film. The simulation result shows that, the uniform height of the abrasives in the contour of the grinding wheel is improved owing to the existence of passivation film in ELID grinding, it is related to the thickness of the passivation film, and processing quality in ELID grinding could be enhanced through controlling of thickness of the passivation film.
Authors: Zhen Tao Shang, Han Huang, S.Q. Wang, Xiao Min Sheng, Hai Qing Mi
Abstract: Electrolytic In-process Dressing (ELID) has been applied in high speed grinding of partially stabilized zirconia. Using a developed electrode system, the ELID effect on a bronze bond diamond wheel was significant. This resulted in a decrease in grinding force, and thus improved the ground surface quality. The improvement of grinding performance was attributed to the good maintenance of wheel sharpness by ELID dressing.
Authors: Z.W. Ren, Yong Qi Wang, Zhen Yuan Jia, X.J. Sheng
Abstract: The physics performance of thin-walled rotary parts made of hard brittle material on high-speed aerocraft cannot meet the technical requirements after semi-finished processing, in order to compensate the physics performance, the wall thickness should be properly grinded based on the inner surface reference in the finish machining. A processing method consisted of measuring, calculating and grinding functions is investigated. The data of complex surface is obtained with trigger measuring technology, and the reconstructed profile is calculated with cubic polynomial approaching algorithm, which has fast and stable merits in suit with efficient machining. The grinding G program is generated according to the concrete construction of machining tool. This method has been verified by experiments.
Authors: Xu Yue Wang, Ren Ke Kang, Wen Ji Xu, Lian Ji Wang, Dong Ming Guo
Abstract: Laser processing of super-abrasive grinding wheel is paying a role in a truing/dressing technique to complement mechanical methods recently. However, normal dressing/truing is difficult owing to the toughness of metal-bond materials and high hardness of diamond abrasive. Both geometric and mathematic models were developed to improve laser processing quality and predict various processing parameters, such as focal offset, and incident power, and power density to perform material removal during laser processing a metal-bond diamond grinding wheel. Various trends of the geometrical features of dressing zone in terms of the varying focal offsets were analyzed. Discussions were also given on dressing-zone geometry control. Experimental studies were carried out using different processing parameters to test the effects of laser poweres on dressing quality. Further grinding-force measurement determined the laser dressing parameters with respect to the wheel surface conditions. The normal force FN reduces up to 20%, while tangential force FT decreases to 7% too.The outcomes were shown well agreement with predicted results.
Authors: Yunn Shiuan Liao, M.Y. Tsai, James C. Sung, Yang Liang Pai
Abstract: The fundamental characteristics of dressing action on the polyurethane pad are investigated via dressing by single diamond of different orientations, dressing parameters and dressing path in this study. Experimental results show that a groove with pile-up on both side walls forms as the diamond moves over the pad with a specific dressing depth. The resulting asperities on the pad are strongly affected by the diamond orientation. Plowing is found to be the major mechanism responsible for this surface topology if dressing is conducted by the face of a diamond. On the contrary, cutting action dominates when the point of a diamond is responsible for dressing. It is also found that dressing velocity has an insignificant effect on the groove and ridges created on the pad. The depth of the groove is smaller than the dressing depth due to the spring back of the pad. When the groove created is repeatedly dressed over the same track, the ridge height and groove depth increases for each additional dressing. When two grooves cross each other, the ridges at the four corners of the intersection grow while the depth of the overlapped area decreases. These ridges will become the pressure enhancer of the abrasives to polish the wafer.
Authors: Pei Lum Tso, Yang Liang Pai
Abstract: The primary consumables in chemical mechanical polishing (CMP) are the polishing pad and slurry. The polishing pad significantly influences the stability of the polishing process and the cost of consumables (CoC). Usually a diamond pad conditioner is used to scrap off the polishing debris from the pad top. Recently, an alternative planarization process can be achieved by polishing with a "fixed abrasive pad" (FAP). In order to dress bumps on FAP, this paper use an amorphous diamond, a diamond-like carbon deposited by cathode arc system as the dresser for FAP. The amorphous diamond can produce a surface relief that ranges from a few nanometers to about 200 nanometers. With the addition of this dressing step on a rotary platform, FAP can renew its polishing surface 10 to 100 times before the bumps are used up. The pad cost for polishing can be reduced by at least ten folds and make FAP more desirable than slurry pad for silicon wafer manufacturer due to its intrinsic capabilities to produce flatter wafers with high polishing rate.
Authors: Yong Bo Wu, Xu Yue Wang, T. Tachibana, M. Kato
Abstract: This paper aims at the development of an alterative technique for truing and dressing a small vitrified CBN grinding wheel used for the internal finishing of small holes measuring several millimeters in diameter. In conventional truing and dressing, a single-tip diamond dresser or a rotary GC cup wheel dresser is employed. This levels off the improvement in the wheel truing accuracy because the stiffness of the grinding wheel shaft with an open-sided structure is low, and the shaft is thus deformed easily due to the truing force. In the present work, a new truing and dressing technique is proposed in which a Nd:YAG laser beam is employed as the dresser. Experiments were carried out with respect to the effects of the laser beam conditions (amplitude, width and frequency of pulse, and focus offset) and the relative motion between the laser beam and CBN wheel. It was found that the run-out of the CBN wheel was decreased significantly, and the wheel surface condition was improved greatly after laser truing and dressing.
Authors: Hiroshi Matsuura, Kazuhiro Hane, Yasuhiro Kunieda, Nobuhito Yoshihara, Ji Wang Yan, Tsunemoto Kuriyagawa
Abstract: The state of the wheel surface after dressing is important for processing of a surface to the nano-order level. A laser dresser was developed using ultraviolet (UV) laser light, which imparts no mechanical damage to the resin bond. One feature of this system is that UV laser energy is transmitted by a special optical fiber for UV light, and is transmitted only to the resin bond. Using this newly developed laser dresser, it was possible to ablate the resin bond to a depth of over 2 microns using a fiber with a core diameter of 200 microns.
Authors: Yasuhiro Kunieda, Hiroshi Matsuura, Sohei Kodama, Nobuhito Yoshihara, Ji Wang Yan, Tsunemoto Kuriyagawa
Abstract: This paper reports a new laser conditioning method for micro-wheels with ultra-fine grit diamond, which are used for the micro grinding of micro-aspherical optics. Resinoid-bonded micro-wheels with ultra-fine grit diamonds are used for micro grinding. Such small wheels have the problem of poor ground surface roughness due to their few effective cutting edges and low peripheral speeds. In the present work, new truing and dressing methods are proposed to produce many effective cutting edges. The new method uses the third harmonic of a Nd:YAG laser, which is suitable for processing resinoid bond material. It was found that a SD1500B wheel treated using the new method had a higher cutting edge density than one treated using a conventional method, the cup truer method. A good surface roughness was obtained using the new method.
Authors: Xiao Jun Wu, Yoshihiro Kita, Kiku Ikoku

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