• Journal of the Korean Society for Precision Engineering
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• v.23 no.1 s.178
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• pp.64-71
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• 2006

Ultraprecision machining and MEMS technology have been taken more and more important position in machining of microparts. Micro endmilling is one of the prominent technology that has wide spectrum of application field ranging from macro parts to micro products. Also, the method of micro-grooving using micro endmill is used widely owing to many merit, but has problems of precision and quality of products due to tool wear and tool fracture. This investigation deals with state monitoring using acoustic emission(AE) signal in the micro-grooving. Characteristic evaluation of AE raw signal, AE hit and frequency analysis for condition monitoring is presented. Also, the feature extraction of AE signal directly related to machining process is executed. Then, the distinctive micro endmill state according to the each tool condition is classified by the fuzzy C-means algorithm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.953-956
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• 1997

Micro drilling characteristics by EDM method was investigated. In detail, Micro tool electrode for EDM drilling was machined by use of WEDG method and micro hole was drilled using the machined tool electrode in SUS plate. The machining accuracy and time was compared in a different dielectric fluid. As a result, it was convinced that this method could be utilized as a fabrication technology of micro mold or micro 3 dimensional parts.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.332-335
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• 1997

With the advance of precision technique, the optical system is more precise and complex and the machining method of optical element which is composed of micro-grooves is developed. Especially, the method of micro-grooving using diamond tool is used widely owing to many merit, but has problems of damage of surface roughness due to tool wear and tool fracture. This paper deals with state monitoring using AE RMS in the micro-grooving. The change of AE RMS is very small with increment of cutting velocity and depth of cut. In spite of constance magnitude of principal force in machining using diamond tool of tool wear and tool fracture, AE RMS is highly fluctuated. Because changing of cutting state has relevance to surface roughness profile, surface toughness profile is expected using AE RMS.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.275-280
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• 2001

Recently, the trends of industrial products grow more miniaturization, variety and mass production. Micro drilling which take high precision in cutting work is requested more micro hole and high speed working. Especially, Micro deep hole drilling is becoming more important in a wide spectrum of precision production industries, ranging from the production of automotive fuel injection nozzle, watch and camera parts, medical needles, and thick multi-layered Printed Circuit Boards(PCB) that are demanded for very high density electric circuitry. This paper shows the tool monitoring results of micro drill with tool dynamometer. And additionally, microscope with built-in monitor inspection show the relationship between burr in workpiece and chip form of micro drill machining.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.452-457
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• 2003

As a fundamental study on developing elements with micro shape, micro mold parts machining and experiment of injection molding using it were performed. The ultra precision micro machining system with high functionality was fabricated, and utilized in the machining of micro parts. By using this machining system and micro end-mill tool, a micro circle column structure of high aspect ratio, diameter 60 $\mu\textrm{m}$, height 500 $\mu\textrm{m}$, was fabricated. And a micro lens molds were fabricated by using ball end-mill tool of 300 $\mu\textrm{m}$ diameter and diamond fly-cut tool of 150 $\mu\textrm{m}$ radius. A micro injection molding machine, which is clamping force 1.75 ton, injection capacity 2.8cc, was fabricated for injection molding experiment using micro molds. The injection molding experiment was performed by using the injection molding machine, micro cylinder structures and lens molds. This paper introduces these micro machining system and injection molding machine and demonstrates examples of injection molding using fabricated molds.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.10
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• pp.52-59
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• 2006

Micro electrical discharge machining (EDM) and micro electrochemical machining (ECM) were studied for the fabrication of micro structures. Micro EDM has been used to machine micro structures from metals. However, since the tool wear is inevitable during the machining, the tool wear is drawback for the precision machining. Micro ECM is also used for micro machining and produces better surface quality than that of micro EDM. Moreover, since tool electrodes are not worn out, micro ECM is suitable for the precision micro machining. However, the machining rate is lower than that of micro EDM. In this paper, therefore, the hybrid machining process which uses micro EDM as roughing and micro ECM as finishing is introduced. By using this hybrid machining, a hemisphere with $100\;{\mu}m$ radius was fabricated and the efficiency of the process was investigated experimentally.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.2
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• pp.5-11
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• 2005

Among the micro machining techniques, micro EDM is generally used for machining micro holes, pockets, and micro structures on difficult-cut-materials. Micro EDM parameters such as applied voltage, capacitance, peak current, pulse width, duration time are very important to fabricate the tool electrode and produce the micro structures. Developed micro EDM machine is composed of a 3-axis driving system and RC circuit equipped with pulse generator. In this paper, using micro EDM machine, the characteristics of micro EDM process are investigated and it is applied to micro holes, slots, and pockets machining. Through experiments, relations between machined surface and voltages and between MRR and feedrate are investigated. Also the trends of tool wear are investigated in case of hole and slot machining.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.217-218
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• 2006

This paper presents an investigation on the characteristics for new micro tool dynamometer by using the ultrahigh-speed air turbine spindle. Recently, the ultrahigh-speed micro flat endmilling has been investigated actively due to request of accuracy improvement and productivity of die and mould manufacturing. To perform efficient ultrahigh-speed micro flat endmilling, evaluation of ultrahigh-speed machinability must be studied preferentially and it can be identified by investigation of cutting force. The cutting forces in ultrahigh-speed micro flat endmilling can be measured by micro tool dynamometer. But general dynamometer has low natural frequency and so is improper for measuring very high frequency cutting forces in ultrahigh-speed micro flat endmilling. In this study, the micro tool dynamometer which has very high natural frequency is newly designed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.167-172
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• 2003

The machining method by using end-milling tool has been applying in machining structures of various shapes because of the availability. Recently, all kinds of industries based on the parts of micro shape are developing, and the demands of mechanical micro machining technology are Increasing suddenly to produce these parts. According to such changes, the technology of the micro end-milling machining is applying as one of the most important machining means. This research is to aim at developing machining technology for various micro structures using micro end-mill. This paper introduces micro mechanical machining system with ultra precision, and demonstrates methods manufacturing all sorts of parts and moldings for industry and examples of applicable machining by using micro end-milling tool of micro sizes from hundreds to tens in diameter.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.10
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• pp.42-49
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• 2004

Electrical discharge machining (EDM) is one of the most extensively used non-conventional material removal process. The recent trend in reducing the size of product has given micro EDM a significant amount of research attention. Micro EDM is capable of machining not only micro holes and micro shafts as small as a few micrometers in diameter but also complex three dimensional micro cavities. But, longitudinal tool wear by electrical discharge is indispensable and this affects the machining accuracy in micro EDM process. Therefore, newly developed tool wear compensation strategy called round trip method is suggested and verified by experiment. In this method, machining depth of cut, overlap effect and critical travel length are also considered.