• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.6
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• pp.38-49
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• 1994

In this study, grindability of some representative engineering ceramics are experimentally investigated using resin bond diamond wheel with conventional surface grinding machine, and proper grinding conditions which can be obtained from various experimental results are established also for mechanical components which are proper to domestic circumstances with high reliability. And through the results of experiment, it is confirmed that grinding energies of the ceramics, especially in the case of $Al_2O_3$, are lower than steel with same machining condition in the conventional grinding because of their fine-brittle fracture mode type removal process, though the ceramics are well-known to unmachinable materials. And moreover, the total pass numbers needed for spark-out process to be completed are depend on their mechanical properties because that grinding stiffness is different from each other. The grinding force, ginding power and ground surface roughness are also measured and compared. Furthermore, the experiments carried out in this study, some useful results are obtained with can guide to grind engineering ceramics with conventional surface grinding machine.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.561-562
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• 2006

To enhance the precision and productivity of ultra precision aspheric surface micro lens, the development of ultra-precision grinding system and process for the aspheric surface micro lens are described. In the work reported in this paper, an ultra-precision grinding system for manufacturing the aspheric surface micro lens was developed by considering the factors affecting the grinding surface roughness and profile accuracy. This paper deals with mirror grinding of an aspheric surface micro lens by resin bonded diamond wheel and spherical lens of BK7. The optimization of grinding conditions on ground surface roughness and profiles accuracy is investigated using the design of experiments.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.3
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• pp.59-65
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• 2002

In the grinding process, the degree of the sharpness in wheel grain affects the surface roughness and the dimensional accuracy. If a wheel with dull grains is used, te grinding force will be increased and the surface roughness deteriorated. To produce a precision component, the magnitude of parameters related to the wear amount of a grinding wheel has to be limited. In this study, a variation of the grinding force and the surface roughness were measured to seek the machining characteristics of the WA and CBN wheels. From the wear amount of the grinding wheel and the removal rate of workpiece, the grinding ratio was calculated. And also the wheel life was determined at a rapid decreasing point of the grinding ratio. The difference between the surface of wheel-workpiece before grinding and after wheel life was clearly verified with a microscopic photo.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1787-1792
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• 2003

Recently with the development of semiconductor technology, the miniaturization of parts and products as well as their high precision is required. In addition, as the national competitiveness is increasingly affected by the development of the micro parts through micro machining technology, the study of the micro machining technology is being conducted in many countries. The goal of this study is to fabricate micro tools under the size of $20{\mu}m$ and to machine micro holes using them. The fabrication is done by grinding and the application of ELID to the grinding wheel. The surface roughness of the micro tools is measured to evaluate the study.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.6
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• pp.694-700
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• 2011

Since polycrystalline diamond (PCD) has high hardness like diamond, it has been used as tool material for lathe and milling of non-ferrite material. A micro tool fabricated from PCD material can be used for micro machining of hard material such as tungsten carbide, glass, and ceramics. In this paper, micro PCD tools were fabricated by micro EDM (electrical discharge machining) and used for micro grinding of glass. Craters generated on the tool surface by EDM spark work as like grits in grinding process. The effects of tool shapes, tool roughness and PCD grain size were investigated. Also studied was a hybrid process combining electrochemical discharge machining (ECDM) and micro grinding for micro-structuring of glass.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.5
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• pp.60-75
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• 1990

Advanced Ceramics have some excellent prosperities as the material for the mechanical component. It is, however, very difficult to grind ceramics with high efficiency because of their high strength, hardness and brittleness. In this study, various machining experiments are carried out to obtain the basic knowledge of grinding High Strength Ceramics with high efficiency and precision for the purpose of application to Automobile parts. Advanced Engineering Ceramics such as Si$_{3}$N$_{4}$, SiC, ZrO$_{2}$, $Al_{2}$O$_{3}$ are ground with diamond wheels using conventional grinding machine. Results obtained in this study provide some useful informations to attain the high efficiency grinding of Advanced Ceramics.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.1
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• pp.9-15
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• 2019

This study focused on the application of ELID mirror-surface grinding technology to the manufacture of off-axis asymmetric large-area reflecting mirrors made of BK7 glass. The size of the parts, such as asymmetric large-area mirrors or lens, made form-accuracy or roughness especially hard to measure after machining because of the measuring range limit of measurement devices. In this study, the ELID grinding system has been set up for mirror-surface machining experiments manufacturing off-axis asymmetric lenses. A measuring method using a reference workpiece has been suggested to measure the form-accuracy and roughness. According to the experimental results, even when using only a reference workpiece, it is confirmed that the surface roughness was 8 nmRa and form-accuracy was 80 nmRMS, with a best fit asymmetric radius when using a grinding wheel of #8,000. It is found that the accuracy of large-area parts could be estimated by the proposed process.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.6
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• pp.52-58
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• 1996

This paper described on the effect of residual stocks in internal grinding of tungsten carbide materials in order to improve the grinding efficiency as well as grinding accuracy. Through the fundamental investigation is carried out for tungsten carbide materials using electroplated diamond wheel, the residual stock after grinding process is effective to the grinding efficiency. The obtained results are as follows: (1) Under the depth of cut(t) is constant and decreasing the workpiece velocity(Vw), the residual stock after grinding is increased, but the difference is little less than the difference by table speed. (2) Increasing the wheel velocity, the residual stock after grinding is decreased. Therefore in order to minimize the residual stock, the wheel velocity should be increased as far as possible. (3) The surface roughness and out-of roundness increased with depth of cut and table speed, and decreased with wheel velocity, but it may as well adopt as much as possible under the dimensional tolerance which is required for high efficiency grinding. (4) In order to remove residual stock, the spark-out grinding shoule be done, and it also can be improved about 20~25% throughout spark-out grinding, and the number of optimal spark-out times were within 10 times.

• Transactions of Materials Processing
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• v.29 no.3
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• pp.144-150
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• 2020

In this paper, we propose the generation of a double enveloping worm thread profile with a non-developable ruled surface. Thread surface machining cuts all the way from the tip to the tooth root at one time, like full-face contact machining, rather than cutting several times like point machining. This cutting can reduce the cutting duration and achieve the smooth surface that does not require a grinding process for the threaded surface. The mathematical model of the cutting process was developed from theoretical equations, and the tooth surface was generated using two parameters and modeled in the CATIA using the generated Excel data. Additionally, the machining process of the worm was simulated in a numerical control simulation system. To verify the validity of the proposed method, the deviation between the modeling and the workpiece was measured using a 3D measuring machine.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.204-209
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• 1999

The dressing time monitoring in cylindrical grinding is very important with respect to machining efficiency. Therefore, the purpose of this paper is to determine the wheel life by monitoring behavior of grinding power for Wa, 19A and GC. For this purpose, we investigated indirectly the attritious wear of grain edge, the loading of grinding wheel and the breakage of grain through the grinding power and the surface roughness under various grinding conditions. From obtained the results, the relationship between the wheel life and the average sectional chip area is examined to guide for the determination of dressing time.