• Title/Summary/Keyword: Diamond Grain

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A study on grinding characteristics of CBN single abrasive grain (CBN 단입자의 연삭특성에 관한 연구)

  • 팽현진;손명환
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.6
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    • pp.1533-1541
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    • 1990
  • Cubic boron nitride (CBN) is known the second hardest material followed diamond and was provided industry as an abrasive grain in the late 1960's. Since the introduction of CBN, a large amount of research has been carried out to determine the best application condition for grinding operation. Despite the advantages in its characteristics, CBN has not yet gained full acceptance as more excellent abrasive grain than traditional one. The reason for this state is that the surface roughness ground by CBN is worse than by traditional one and dressing and truing is very difficult. This led user's resistance to the use of CBN as an abrasive grain. Present study is to investigate the cause of lower surface roughness ground by CBN single crystal abrasive grain comparing with traditional one.

Effects of BMR Variety and Corn Grain (Grounded) Supplement on Silage Quality of Sorghum × Sudan Hybrids (수수 · 수단그라스 사일리지 제조에 있어 BMR 품종과 파옥쇄 첨가 효과)

  • Kwon, Chan Ho;Kim, Eun Joong;Cho, Sangbuem
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.34 no.4
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    • pp.240-246
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    • 2014
  • The present study was conducted to evaluate the productivity of $Sorghum{\times}sudangrass$ (SX17) hybrid and BMR (brown mid rib) $Sorghum{\times}sudangrass$ hybrid and silage quality of these forages with corn grain supplementation. The effect of corn grain supplementation on the quality of silages was also investigated. No remarkable differences at growth characteristics and productivities in two hybrids were found. Sugar content, however, in stem of BMR hybrid showed significantly great (p<0.05) and the difference between two hybrids was about $2B^{\circ}$. Ratio of lactic acid in total organic acid in BMR hybrid (82.8%) was significantly greater than the control (SX17 hybrid) (78.5%) (p<0.05). Ratio of butyric acid in total organic acid in SX17 hybrid (18.5%) was significantly greater than BMR hybrid (9.8%) (p<0.05). According to the result of organic acid ratio, it could be assumed that the use of BMR hybrid can improve silage quality. NDF and ADF contents in both SX17 and BMR hybrids were significantly declined with increased corn grain supplementation (p<0.05). Different TDN values in SX17 (56.2) and BMR (57.1) hybrids were detected. However, TDN values of both SX17 and BMR hybrid silages were significantly elevated by increasing the proportion of ground corn (p<0.05).

Evaluation for Grinding Performance of Ceramics (세라믹 재료의 연삭성능 평가)

  • 정을섭;김성청;김태봉;소의열;이근상
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2001.10a
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    • pp.355-359
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    • 2001
  • In this study, experiments were carried out to investigate the characteristics of grinding and wear process of diamond wheel grinding ceramic materials. Normal component of grinding resistance of $AI_2O_3$ was less then that of $Si_3N_4$ and $ZrO_2$. It is because the resistance for grain shedding is less then that for layer formation. For the case of $Si_3N_4$ and $ZrO_2$, as the grain mesh number of wheel increases, the surface roughness decreases. For the case of $AI_2O_3$, the surface roughness does not decreases. For the case of $Si_3N_4$ and $ZrO_2$, grinding is carried out by abrasive wear processes. For the case of $AI_2O_3$, grinding is carried out by grain shedding process.

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Wear and Wear Transition Mechanisms During Sliding in Al2O3 (Al2O3에서 미끄럼시의 마모 및 마모천이 기구)

  • 조성재;김종집;한준희;문한규
    • Journal of the Korean Ceramic Society
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    • v.26 no.1
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    • pp.51-58
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    • 1989
  • Wear and wear transition mechanisms during sliding as a function of time in Al2O3 have been studied to understand the wear behaviour of brittle ceramic materials. Commercial Si3N4 ball was rotated against flat Al2O3 specimens which were hot pressed and polished using upto 1${\mu}{\textrm}{m}$ diamond paste. Paraffin oil was used as a lubricant. Experimental data show that wear of Al2O3 is separated into distinct two stages, i.e., initial stage of slow wear and final stage of rapid wear. Microstructural observations at worn surface show that wear occurs through grooving and grain pull-out in the initial and final stage respectively. TEM observations beneath the worn surfaces show that grain pull-out starts to occur by the propagation of grain boundary cracks induced by dislocation pile-up throughthe surface.

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Fabrication of PCD Micro Tool and its Hybrid Micro Machining (다결정 다이아몬드를 이용한 미세 공구 제작과 이를 이용한 미세 복합 가공)

  • Doan, Cao Xuan;Kim, Bo-Hyun;Chung, Do-Kwan;Chu, Chong-Nam
    • 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.

Study on Grinding Force and Ground Surface of Ferrite (페라이트의 연삭저항 및 연삭면 특성)

  • 김성청
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.6 no.3
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    • pp.17-25
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    • 1997
  • This paper aims to clarify the effects of grinding conditions on the grinding force, ground surface and chipping size of workpiece in surface grinding of various ferrites with the resin bond diamond wheel. The main conclusions obtained were as follows: In a constant peripheral wheel speed, the specific grinding energy is fitted by straight lines with grinding depth coefficient($\delta$) in a logarithmic graph. The effect of both depth of cut and workpiece speed on grinding energy becomes larger in the order of Mn-Zn, Cu-Ni-Zn and Sr. When using the diamond grain of the lower toughness, the roughness of the ground surface becomes lower. The ground surfaces show that the fracture process during grinding becomes more brittle in the order of Sr, Mn-Zn and Cu-Ni-Zn. The chipping size at the corner of workpiece in grinding increases with the the increases of the depth of cut and workpiece speed, and the decrease of peripheral wheel speed. The effect of both depth of cut and workpiece speed on chipping size becomes more larger in the order of Sr, Mn-Zn and Cu-Ni-Zn.

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A study on the grinding machining of engineering ceramics with high efficiency using "In-process dressing" (연속 드레싱 공정을 도입한 엔지니어링 세라믹스의 고능률적 연삭 가공에 관한 연구)

  • 강재훈;이재경
    • Journal of the korean Society of Automotive Engineers
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    • v.15 no.2
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    • pp.130-143
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    • 1993
  • Engineering ceramics have some excellent properties as the material for the mechanical components. It is, however, very difficult to grind ceramics with high efficiency because of their high strength, hardness and brittleness. In this paper, experiments are carried out to obtain the effect of "In-process dressing" to grind the Engineering ceramics with high efficiency. To save running time for dressing process and obtain restraint effect of diamond grain wear, "In-process dressing" system using WA stick type honing stone is proposed. Representative Engineering ceramics, such as AI$_{2}$O$_{3}$, Si$_{3}$N$_{4}$, are ground with diamond wheel. Also bending strength test is carried out to check upward tendancy of mecahnical properties as the result of machining defact restraint through the grinding machining method using "In-process dressing" process. Some results obtained in this study provide useful information to attain the high efficiency grinding and the high mechanical properties of Engineering ceramics.rties of Engineering ceramics.

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Characterization of structural and field-emissive properties of diamond films in terms of growth conditions and additive gases (증착변수 및 첨가가스에 따른 다이아몬드 박막의 구조적 물성 및 전계방출 특성의 변화 분석)

  • Park, Jae-Hyun;Lee, Tae-Hoon;Park, Chang-Kyun;Seo, Soo-Hyung;Park, Jin-Seok
    • Proceedings of the KIEE Conference
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    • 2003.07c
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    • pp.1571-1573
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    • 2003
  • Diamond films including nanocystalline and graphite phase are grown by microwave plasma chemical vapor deposition using $N_2$ additives and negative substrate bias at growth step. The microstructure of the films is controlled by changing $N_2$ gas ratio and negative bias. Defects and grain boundaries between diamond and graphite are proposed to be crucial factors for forming the conducting path of electron emissions. The effect of growth parameters on the film microstructure are investigated by Raman spectroscopy and scanning electron microscopy(SEM). Electron emission characteristics are also examined in terms of the film growth conditions.

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A study on the surface grinding machining of Engineering ceramics using "In-process dressing" method (연속 드레싱 공정을 이용한 엔지니어링 세라믹스의 평면 연삭 가공에 관한 연구)

  • Kang, Jae-hoon;Heo, Seoung-jung;Kim, Won-il
    • Journal of the Korean Society for Precision Engineering
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    • v.10 no.2
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    • pp.178-189
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    • 1993
  • Engineering ceramics have some excellent properties as the material for the mechanical components. It is, however, very difficult to grind ceramics with high efficiency because of their high strength, hardness and brittleness. In this paper experiments are carried out to obtain the effect of "In-process dressing" to grind the Engineering ceramics with high efficiency. To save running time for dressing process and obtain restraint effect of diamond grain wear, "In-process dressing" system usint WA stick type honing stone is proposed. Representative High Strength Engineering ceramics A1$_{2}$O$_{3}$ and Si$_{3}$N$_{4}$are ground with diamond wheel. Also bending strengrh test is carried out to check upward tendancy of mecahnical properties as the result of machining defact restraint through the grinding maching method using "In-process dressing" process. Some results obtained in this study provide useful information to attain the high efficency grinding and the high mechanical properties of Engineering ceramics.rties of Engineering ceramics.

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The Study on the WEDM of Polycrystalline Diamond (다결정 다이아몬드의 와이어방전가공에 관한 연구)

  • Kim, Chang-Ho;Kang, Jae-Won;Oh, Jang-Uk;Seo, Jae-Bong
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.7 no.3
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    • pp.67-74
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    • 2008
  • Polycrystalline diamonds(PCD) tools are widely used in machining a large variety of advanced materials. However, the manufacture of PCD tool blanks is not an economical process. The shaping of PCD blanks with conventional machining methods(such a grinding) is long, labor-intensive process. This paper reports experimental investigation of the influence of electrical machining conditions on the metal removal rate of WEDM of PCD. Experimental results show that the longer pulse-on time and the shorter pulse-off time increase the metal removal rate and worsen the surface quality. The smaller grain size of diamond yields the metal removal rate and shows the better surface quality. Higher electrical conductivity of water yields worse surface roughness.

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