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  • Title/Summary/Keyword: ceramic tool

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Machinability of CBN Tools in Interrupted Milling Process of Die & Mold Steels with High Hardness (고경도 금형강 단속 밀링절삭에 대한 CBN 공구의 가공 성능)

  • Song, Jun-Hee;Mun, Sang-Don
    • Korean Journal of Metals and Materials
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    • v.48 no.7
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    • pp.651-659
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    • 2010
  • When high-speed interrupted cutting is carried out for die and mold steels with high hardness, CBN tools manifested a significantly longer wear life than carbide, ceramic, or cermet tools in an experiment of face milling characteristics. In addition, it was also found that they secured a stable surface roughness within a range of 1.6 S~6.3 S, an acceptable range for precision machining for polished machining parts. And it makes them acceptable in the precision machining field, except in industries where very high machining accuracy is required. In the high hardness interrupted cutting, it was advantageous to perform a negaland treatment and a honning treatment on the tools' cutting edge to extend tool life and surface roughness. Also, severe crater development was found on the sloped face in CBN tools following high-speed machining. This caused the cutting edge to be weakened and damaged, and ultimately resulted in a shorter tool life. Finally, as a result of EDX mapping inspection, Cr component was detected evenly on the entire crater wear area, which can be included only in STD 11.

A Study on the Friction and Wear Characteristics of TiC, TiN and Ti(CN) with PECVD Process (PECVD 공정에 의한 TiC, TiN 및 Ti(CN)의 마찰 마모 특성 연구)

  • Rhee Bong Goo;Jeon Ghan Yeol;Kim Jung Ki;Kim Dong Hyun;Oh Seong Mo
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.14 no.2
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    • pp.1-7
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    • 2005
  • In order to determine the wear Properties of PECVD ceramic coatings, wear process was evaluated using the coated pin of Falex Tribosystem. Coating materials deposited wear the TiC, TiN and Ti(CN). An experimental process was established to determine the tribological characteristics of friction and wear behavior under the variation of applied load, temperature and sliding distance by the Falex test machine. The experimental results indicate that TiN coating compared with TiC coating on e materials have e excellent friction and wear characteristics. However TiC coating compared i친 TiN coatings have a low friction coefficient with steel and good thermal stability, and Ti(CN) has the excellent anti-wear properly as well as the superiority of extreme pressure property. Compound coating compared wi simple coatings show improved tribological characteristics.

A study on the micro hole machining of Al2O3 ceramics (Al2O3 세라믹의 미세구멍 가공에 관한 연구)

  • 윤혁중
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1997.10a
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    • pp.37-42
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    • 1997
  • This paper describes result of experiment of parameters affecting the micro hole drilling time, kind of assisting gas and it's pressure. The result reveals that parameter value of 0.08J, 20Hz, dwell time of 300 microseconds can be a good machining condition to make micro hole diameter range of 50-70{\mu}{\textrm}{m}, Assistant gas such air, O2, Ar, N2 was adapted. Assistant gas of air makes heat affected zone enlarge due to burning of material, also it makes hole irregular and damage because of refusion stick to caused by chemical reaction with Al2O3 ceramic material. O2(99.9%) has good characteristic to get good drilling and smooth surface on pressure of 0.2kgf/cm2, but it is expensive. Ar, N2 makes material burn and crack severely and proved to be an appropriate but, Ar was better than N2.

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A Study on the Grindability of New Ceramics (뉴 세라믹스의 연삭성에 관한 연구)

  • Kim, Seong-Kyeum;Kim, Nam-Hoon
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.16 no.3
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    • pp.103-108
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    • 2007
  • The number of parts made of ceramic materials has gradually been increasing in field of from mechanical engineering to electronics engineering and, mechanical engineering ceramics have spread because of three very favourable characteristic features of their application, namely, heat, wear, and corrosion resistance. therefore, the elaboration of suitable grinding technologies is Important. grinding is problematic because crack-free ceramics are difficult to process owing to their particular micro structure. In this paper we report on the application of advanced precision grinding process, elaborating continuous wheel dressing. The removal rate can be increased significantly and surface roughness is improved. Various problems(roughness, ground surface etc)encountered in grinding of ceramics are also discussed.

Tribological Characteristics with Purity Zirconia of Compression Ring Materials in Piston (피스톤 압축 링 재료의 지르코니아 순도에 따른 트라이볼로지 특성)

  • Oh, Seong-Mo
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.15 no.5
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    • pp.91-96
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    • 2006
  • The friction and wear properties of ceramics are very important in the applications to engineering ceramic parts such as seal rings, pump parts, automobile meter parts, and so on. In this study, the effects of each other purity on the mechanical and tribological properties of purity zirconia ceramics were investigated. Also in order to determine the effects of sliding distance, sliding speed, contact load, friction coefficient, the amount of worn out material at a certain time, and the prepared composites were measured. Crystalline phases and microstructure were examined with XRD and SEM. The results show that we obtained the good properties of friction coefficient and wear resistance at the purity 99.5% of zirconia. than this of the purity 95% were great at the wear amount of worn out material.

An Evaluation of the Effect of Micro-cracks on Macro Elastic Moduli (매크로 탄성 계수에 미치는 마이크로 크랙의 영향 평가)

  • Kang, Sung-Soo;Kim, Hong-Gun
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.15 no.5
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    • pp.97-103
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    • 2006
  • A meso-scale analysis method using the natural element method, which is a kind of meshless method, is proposed for the analysis of material damage of brittle microcracking solids such as ceramic materials, concrete and rocks. The microcracking is assumed to occur along Voronoi edges in the Voronoi diagram generated using the nodal points as the generators. The mechanical effect of microcracks is considered by controlling the material constants in the neighborhood of the microcracks. The macro elastic moduli of anisotropic as well as isotropic solids containing a number of randomly distributed microcracks are calculated in order to demonstrate the validity of the proposed method.

오일제트윤활방식의 25,000rpm급 모터내장형 고속주축계의 진동특성에 관한 연구

  • 이용희;김석일;하재용
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1995.10a
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    • pp.846-851
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    • 1995
  • A motor-integrated high-speed spindle system with .psi. 65*25, 000rpm is modeled for analytical and experimental studies related to the dynamic characteristics. And the systematic and rational identification processes for evaluating the material properties of spindle and built-in motor is introduced. The impulse excitation method is applied for the experimental model testing, and the dynamic characteristics of test model is theoretically analysed by using the finite element method based on Timoshenko theory. Especially, the experimental and theoetical results reveal that the test model under the required operational conditions has no critical problem for dynamic characteristics.

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Thermal flow intensity factor for non-homogeneous material subjected to unsteady thermal load (비정상 열 하중을 받는 이질재료의 열량 집중 계수 해석)

  • Kim, Gui-Seob
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.16 no.4
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    • pp.26-34
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    • 2008
  • This article provides a comprehensive treatment of cracks in non-homogeneous structural materials such as functionally graded materials (FGMs). It is assumed that the material properties depend only on the coordinate perpendicular to the crack surfaces and vary continuously along the crack faces. By using laminated composite plate model to simulate the material non-homogeneity, we present an algorithm for solving the system based on Laplace transform and Fourier transform techniques. Unlike earlier studies that considered certain assumed property distributions and a single crack problem, the current investigation studies multiple crack problem in the FGMs with arbitrarily varying material properties. As a numerical illustration, transient thermal flow intensity factors for a metal-ceramic joint specimen with a functionally graded interlayer subjected to sudden heating on its boundary are presented. The results obtained demonstrate that the present model is an efficient tool in the fracture analysis of non-homogeneous material with properties varying in the thickness direction.

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Development of a High-speed Line Center using Linear Motor Feed System and High-speed Spindle System (리니어 모터 이송계와 고속 주축을 적용한 초고속 라인 센터 개발)

  • 문홍만;백영종;조현택;최대봉
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.107-112
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    • 2003
  • The recent machine tools are requested so high-quality processing and productivity increasing. Therefore, it is so necessary to develop technology for high-speed and high-precision. This thesis touches on the development of high speed and intellectual line center. At first, the line center is necessary that strong structure, compact structure and light weight design for high-speed processing and transfer. So, it is necessary that examination of new materials and structures for light-weight and control devices for precision processing. So, it is going to make mention of the process of 1st model production for the above-mentioned based on test model production and evaluation.

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역극성시 금속수지복합체와 세라믹수지복합체의 형상방전가공 특성

  • 우정윤
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1996.10a
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    • pp.52-57
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    • 1996
  • Conductive Ceramic Matrix Composite(CMC) of TIC/Al2O3 and Metal Matrix Composite (MMC) of SiC/Al were experienced by the die sinking Electrical Discharge Machining(EDM) for different current and duty factor according to negative polarity. Inthis experimental study Material Removal Rate(MRR) maximum surface roughness four point bending stress distribution and Scanning Electron Microscopy(SEM) Photographs were analysed. the higher MRR was obtained for CMC than MMC but slowly decreased around duty factor of 0.67 for MMC and better surface morphology was found CMC than MMC. The SEM photographs of discharge traces for CMC showe uniform shape about 100 to 200{\mu}{\textrm}{m} in diameter but MMC showed irregular shape.

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