• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.166.1-166.1
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• 2016

각종 부품의 내마모성 및 내식성을 개선하기 위해서 금속물질에 나노두께의 보호막층을 입혀 경도를 높이는 표면처리 기술이 개발되고 있다. TiN막은 기계적 경도, 내마모성 및 내식성이 우수하여 수없이 연구되어 왔으며 박막의 두께에 따라 다양한 색상표현이 가능하다는 연구도 진행되고 있다. 이러한 TiN 박막의 연구결과로 높은 경도와 강도를 요하는 절삭공구에 하드 코팅을 이용하여 높은 절삭력으로 고효율적인 작업환경을 조성할 수 있다. 기존에 연구되어 온 TiN박막은 Ar과 N2의 혼합가스 분위기에서 증착된 반면 본 실험에서는 영구자석을 이용한 고밀도 플라즈마로 높은 점착성과 균일한 박막 및 대면적 공정이 가능한 RF-magnetron sputtering방법을 이용하여 N2 분위기에서 TiN박막을 $100^{\circ}C{\sim}400^{\circ}C$의 온도범위에서 $100^{\circ}C$간격으로 열처리 후 증착하여 비교실험을 하였다. 이와 같이 제작된 TiN박막을 XRD(X-ray Diffraction)를 사용하여 결정성을 확인한 결과 온도가 높을수록 (111)방향의 결정성장이 뚜렷하게 나타났으며 그 외 Scratch Test와 HM-220(Micro-vicker's tester)를 사용하여 경도특성을 확인하고 SEM(Scanning Electron Microscope), AFM(Atomic Force Microscope)를 이용하여 박막의 표면형상을 측정하였다. 이러한 측정 결과로 향후에는 높은 내마모성 및 초경도가 요구되는 절삭공구 및 경질표면코팅이 필요한 금속산업분야에 적용이 가능 할 것이라 사료된다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.103-108
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• 2018

In interrupted cutting, the workpiece has a groove that impacts both the cutting tool and the workpiece. Therefore, cutting tool damage occurs rapidly. In this study, I performed interrupted cutting of carbon steel for machine structures (SM20C) using an uncoated carbide tool (SNMG120404, P20), and observed tool damage, cutting chip shape, and the workpiece surface. Results: Under the specific cutting conditions of feed rate = 0.066 mm/rev, cutting speed = 120 m/min, and depth of cut = 0.1 mm; and feed rate = 0.105 mm/rev, cutting speed = 120 m/min, and depth of cut = 0.2 mm, the observed tool damage was small. Similar chip shape was observed (Expt. No. 1, 3, 7). Workpiece damage was observed (Expt. No. 3, 5, 7, 9).

• Journal of the Korean Society for Precision Engineering
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• v.25 no.12
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• pp.47-54
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• 2008

Hard turning process can be defined as a single-point machining process carried out on "hard" materials. The process is intended to replace or limit traditional grinding operations that are expensive, environmentally unfriendly, and inflexible. The purpose of this study is to achieve a systematic understanding of machining characteristics and the effects of machining parameters on cutting force, tool wear shape and chip formation by the outer cutting of a kind of wear resistant tungsten carbide V30. Hard turning experiments were carried out on this alloy using the PCD (Poly Crystalline Diamond), cBN (cubic Boron Nitride) and PcBN (Polycrystalline cubic Boron Nitride) cutting tools. The PcBN and the usual cBN tools were used to be compare with the PCD tool and the dry turning was carried out. The PcBN is attractive as the tool material which replaces the PCD. The tool wear width and cutting force were measured, and the worn tool and chip were observed. The difference of the tool wear mechanism among the three tool materials was investigated.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.6
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• pp.159-166
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• 2013

In order to develop the optimum shape of an MQL carbide end-mill suitable for high speed machining of wing ribs which are a detailed part of larger wing structures, using a new material Al-Li alloy, a new MQL carbide end-mill is created that has various quantities of holes, hole sizes, and hole locations. A theoretical machining graph is generated using the hammer test and FRF simulation, and a machining test is performed in order to verify the machining stability in the high speed machining area. The optimum configuration of the MQL carbide end-mill is also presented through comparing the chattering, machining noise and cutting conditions, including the maximum cutting depth, rpm, and feed rate per teeth, for each cutter.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.898-901
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• 2000

It is known that Si3N4 ceramic insert has less hardness than Al2O3 ceramic insert. But Si3N4 ceramic insert has not only high toughness and strength but also low thermal expansion coefficient, which makes it has longer tool life under thermal stress condition. In this study, commercial Si3N4 ceramic insert and home-made SiC-Si3N4 ceramic insert which has different sintering time and chemical composition is tested under various cutting conditions. The experimental result is compared in terms of tool life and cutting force. Generally, As the cutting speed and the feed rate increased, the cutting force and the flank wear increased too. The performance of SiC-Si3N4 ceramic insert shows the possibility to be a new ceramic tool.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.919-922
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• 1997

In this study, the amount of WC and group N elements of Ti(C, N) cermet tool was investigated. The composition of WC was changed from 5 to 20% to determine the effect of WC on the cutting performance of cermet tool. The more WC was added, the longer the tool life of the cermet tool was. The cermet with 20% WC showed the best fracture toughness. The effect of group N elements ; ZrC, ZrN and HfC was also investigated by adding each of them to manufacture the cermet tool with fixed 14% WC composition. The cermet with 1% group N ZrC and 14% WC showed the best cutting performance among the investigated cermet tools.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.401-402
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• 2006

• Journal of the Korean Society for Precision Engineering
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• v.27 no.5
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• pp.14-21
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• 2010

In this study, presintered low purity alumina ceramics were machined with various tools to clarify the effects of the tool material, cutting condition and tool geometry on machinability. The main conclusions obtained were as follows. (a)The wear of tungsten carbide tool becomes smaller with the increase of the feed and clearance angle, and with the decrease of rake angle, especially exhibiting considerably smaller wear with both the decrease of rake angle and the increase of clearance angle. (b) So far as turning the ceramic presintered at low temperature, the diamond tool shows the best performance with higher feed. (c) The effect on the tool wear of the feed, clearance angle and rake angle becomes smaller in turning the ceramic presintered at higher temperature. (d) The tool wear is not severely affected by the depth of cut.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.137-142
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• 1995

고정밀도와 높은 생산성을 갖는 가공방법은 좋은 제품을 값싸게 제작하여야 하는 당면과제를 해결하기 위하여 필수적인 조건이 되었다. 이를 위하여 우선적으로는 공작기계가 고강성과 고속용 스핀들을 지녀야하며 정밀한 신속한 위치제어가 가능해야한다. 이와 더불어 절삭가공의 최첨병인 절삭공구가 고속가공에서 고정밀도와 오랜수명을 보장하는 우수한 성능 또한 가장 중요한 요소중의 하나이다. 이를 위하여 고속도강으로부터 시작하여 초경합금, ceramic, CBN & PCD 공구로 이르는 고속용 재종개발이 계속되었고 또한 절삭저항의 감소와 원활한 칩배출을 위한 형상개발이 꾸준히 이루어져왔다. 이와 함께 주어진 공작기계와 공구를 사용하여 최고의 효율과 정밀도를 유지할 수 있는 최적의 절삭조건의 선정과 적용 또한 중요하다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.85-91
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• 2013

The machinability of wear-resistible tungsten carbides and the tool wear behavior in machining of V30 and V50 tungsten carbides using PCD (Poly Crystalline Diamond) cutting tool was investigated to understand machining characteristics. This material is one of the difficult-to-cut materials in present, but their usage has been already broadened to every commercial applications such as mining tools, and impact resistant tools etc. Summary of the results are as follows. (1) Tool wear progression of PCD tools in turning of wear-resistible tungsten carbides were observed specially fast in primary cutting distance within 10m. (2) Three components of cutting resistance in this research were different in balance from the ordinary cutting such as that cutting of steel or cast iron. Those were expressed large value by order of thrust force, principal force, feed force. (3) If presume from viewpoint of high efficient cutting within this research, a proper cutting speed was 15m/min and a proper feed rate was 0.1mm/rev. In this case, it was found that the tool life of PCD tool was cutting distance until 230m approximately. (4) In cutting of wear-resistible tungsten carbides such as V30 and V50, it was recognized that the tool wear rate of V30 was very fast as compared with V50. (5) When the depth of cut was 0.1mm, there was no influence of the feed rate on the feed force. And the feed force tended to decrease as the cutting distance was long, because the tool was worn and the tool edge retreated. (6) It was observed that the tungsten carbides were adhered to the flank.