• 한국안전학회지
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• 제25권5호
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• pp.1-6
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• 2010

When the ceramic material is being machined, micro crack and brittle fracture dominate the process of material removal. Generally, ceramics are very difficult-to-cut materials and machined using conventional method such as grinding and polishing. However, such processes are generally cost-expensive and have low material removal rate. Machinable ceramics used in this study contain BN powder to overcome these problem and for productivity elevation. This paper focuses on machinability evaluation during end mill process with CNC machining center in this study. Experiment for this purpose is performed for tool wear patterns and mechanism.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.739-742
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• 2000

Micro machining technology has been studied to fabricate small size and high accuracy milli-structure products. To perfectly overcome the conventional mechanical machining methods, the chemical mechanical micro machining(C3M) process was developed. The mechanism of C3M process is that chemical solution etches the material and results in the generation of the chemical reacted layer, and the mechanical micro tool subsequently removes the layer. From the fundamental experiments, the C3M process has been founded to have the advantages of lower machining resistance, tool wear, and higher surface quality and form accuracy than conventional methods. This study focuses on the micro grooving of both the metallic material(SKDII, A1) and hard brittle silicon oxide.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.988-992
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• 2002

Ultrasonic machining technology has been developed over recent years for the manufacture of and quality-assured precision parts for several industrial application such as optics, semiconductors, aerospace, and automobile application. The past decade has seen a tremendous in the use of ceramics in structural application. The excellent thermal, chemical and wear resistance of these material can be realized because of recent improvements in the overall strength and uniformity of advanced ceramics. Ultrasonic machining, in which abrasive particles in slurry with water are presented to the work surface in the presence of an ultrasonic-vibrating tool, is process which should be of considerable interest, as its potential is not limited by the electrical or chemical characteristics of the work material, making it suitable for application to ceramics. This paper intends to further the understanding of the basic mechanism of ultrasonic machining for brittle material and ultrasonic machining of ceramics based in the fracture-mechanic concept has been analyzed.

• 한국표면공학회지
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• 제36권2호
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• pp.206-213
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• 2003

Effects of plasma nitriding on the surface characteristics of tool steels have been investigated using wear tester, micro-hardness tester and scanning electron microscope (SEM) Commercial SKD 11 and SM45 alloy were used as specimens and were plasma nitrided using a plasma nitriding equipment for 5 hr and 10hr at $500^{\circ}C$. Microstructure and phase analysis were performed using SEM and XRD. It was found that plasma nitriding for lour at $500^{\circ}C$, compared with plasma nitriding for 10hr at $500^{\circ}C$, had a thick nitrided layer and produced a layer with good wear resistance and hardness as nitriding time increased. SKD11 alloy showed that wear resistance and hardness decreased, whereas surface roughness increased, compared with SM45 alloy.

• 한국표면공학회지
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• 제28권6호
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• pp.343-351
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• 1995

Titanium nitride films have been prepared on various substrates (silicon wafer, HSS) by cathode arc ion plating process to measure microhardness, adhesion and wear-resistant behaviors by changing the substrate bias voltages (0∼-300V), thickness and roughness. Microhardnesses were measured by micro vickers hardness tester, the adhesion strengths were evaluated by acoustic signals through the scratch test with incremental applied load. As the substrate bias voltages were increased, the ｛111｝ orientation was predominant, the microhardnesses and adhesion strengths of tool steel were observed to be stronger than those of without subatrate bias voltage. Adhesion strengths of the substrate bias were 4-7 times higher than those of without the substrate bias, confirmed by SEM with EDX. Wear resistances were used pin-on-disk tribotester and TiN costing reduced the abrasive wear. As the substrate bias was increased, the weight loss and the friction coefficient was decreased.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.245-250
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• 2002

A successful on-line monitoring system for conventional machining operations has the potential to reduce cost, guarantee consistency of product quality, improve productivity and provide a safer environment for the operator. In fee-shape machining, typical signs of tool problems such as vibration, noise, chip flow characteristics and visual signs are almost unnoticeable without the use of special equipment. These characteristics increase the importance of automatic monitoring in fine-shape machining; however, sensing and interpretation of signals are more complex. In addition, the shafts of the micro-tools break before the typical extensive cutting edge of the tool gets damaged. In this study, the existence of a relationship between the characteristics of the cutting force and tool usage was investigated, and tool breakage detection algorithm was developed and the fellowing results are obtained. In data analysis, didn't use a relative error compare which mainly used in established experiment and investigated tool breakage detection algorithm in time domain which can detect AE and cutting force signals more effective and accurate.

• 한국공작기계학회논문집
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• 제16권1호
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• pp.80-85
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• 2007

High speed cutting is a machining process which cuts materials with the fast movement and rotation of a spindle in a machine tool. High speed cutting leaves a plastically deformed layer on the machined surface. This deformed layer affects in various forms to the surface roughness of machined parts such as the dimensional instability, the micro crack. The surface roughness is called surface integrity which is very important in precision cutting. This paper aims to study on the machined surfaces characteristics of aluminum alloy and brass by AFM(Atomic force microscope) measurement. The objective is contribution to ultra- precision cutting by exhibit foundation data of surface roughness and tool wear when parts are cutting with diamond tool at the factory.

• 한국정밀공학회지
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• 제2권3호
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• pp.77-83
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• 1985

Adaptive control technique for a milling process is developed and implemented in an NC milling machine retrofitted to enable the micro-computer control. The control algorithm has the objects to guarantee the optimal tool life which can give the predetemined allowable lower limit of surface roughness. The experimental results show 1) that the extended tool life equation has good reliability in normal tool wear conditions. 2) and that the proposed adaptive control technique, which determine the optimal cutting condition by basing on the tool life equation modified continually according to the tool wear measured in real time, performs well.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1080-1084
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• 2001

In manufacturing a micro die with half spherical cavity by MEDM, it is necessary to prepare an electrode with the same shape. This paper suggests a simple method to manufacture a half spherical electrode based on tool wear. The tool wears more rapidly at the edge of a cylindrical electrode. In order to make a half spherical micro electrode, cylindrical electrode was fed into the workpiece by the distance of its radius. The d/R(depth/Radius) value varied with respect to capacitance and electrode diameter. The smaller the size of electrode was, the closer the electrode tip geometry approached to a half sphere.

• 한국정밀공학회지
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• 제22권5호
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• pp.37-44
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• 2005

In this paper, wire electrochemical machining (Wire ECM) with ultra short pulses is presented. Platinum wire with $10{\mu}m$ diameter was used as a tool and 304 stainless steel was locally dissolved by electrochemical machining in 0.1M $H_{2}SO_4$ electrolyte. Wire ECM can be easily applied to the fabrication of arbitrarily shaped micro-grooves without tool wear. The change of machining gap according to applied pulse voltage, pulse on-time and pulse period was investigated and the optimal pulse condition for stable machining was obtained. Using this method, various micro-grooves with less than $20{\mu}m$ width were fabricated.