• Title/Summary/Keyword: grinding rate

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A Study on the Grinding Characteristics of the Quartz (Quartz의 연삭 특성에 관한 연구(I))

  • Im, Jong-Go;Ha, Sang-Baek;Choi, Hwan;Lee, Jong-Chan
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.05a
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    • pp.870-873
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    • 2000
  • This investigation reports the grinding characteristics of quartz. Grinding experiments were performed at various grinding conditions including wheel mesh, table speed and depth of cut. The grinding forces and specific grinding energies were measured to compare the grindability of quartz with those of structural ceramics such as A1$_2$O$_3$, SiC, Si$_3$N$_4$ and ZrO$_2$. Surface roughness was also measured with tracer and the ground surfaces were observed with SEM. The chip formation energy of quartz was about 6J/㎣, which is quite smaller than those of structural ceramics. Although plastic flows are occured in Si$_3$N$_4$ and ZrO$_2$, micro/macro cracks are occured in ground surface of quartz like in A1$_2$O$_3$ and SiC.

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Effect of Grinding Method and Grinding Rate on the Dry Beneficiation of Kaolin Mineral (분쇄방식 및 분쇄율이 고령토 광물의 건식 정제에 미치는 영향)

  • Kim, Sang-Bae;Choi, Young-Yoon;Cho, Sung-Baek;Kim, Wan-Tae
    • Journal of the Mineralogical Society of Korea
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    • v.21 no.2
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    • pp.129-138
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    • 2008
  • The characteristics of beneficiating kaolin mineral by liberation (selective grinding) and air classification have been investigated, comparing the grinding rates of ball mill and impact mill. The ore was ground using a ball mill and a impact mill to evaluate the grindability of the two grinding methods based on the constant production amount of fine particles in size less than 325 mesh. Then, the fine product was further separated into two fractions using an air-classifier and each fraction was chemically analyzed to compare the beneficiation efficiency of the two grinding methods. The chemical grade of kaolin mineral decreased as increasing the grinding rate of both the mills. particularly in the case of ball mill because of overgrinding impurities such as quartz and feldspar. In the case of the ball milling, the fine fraction less than 325 mesh was air-classified at a cutting point of $43\;{\mu}m$. The production rate of the air-classified concentrate was found to be 66.2 wt%, removing 5.3% of $Fe_2O_3$ and 34.6% of CaO. Under the same conditions mentioned above with the impact mill, the production rate of the air-classified concentrate was 64.4 wt%, removing 34.2% of $Fe_2O_3$, 67.6% of CaO and 25.0% of $TiO_2$. Therefore, our results indicate that impact mill is superior to ball mill in terms of impurity removal.

Grinding Kinetics of Calcite, Pyrophyllite and Talc During Stirred Ball Milling - Consideration of Selection Function (교반 볼밀에 의한 방해석, 납석, 활석의 분쇄 시 분쇄속도론에 관한 연구 - 선택함수의 고찰)

  • Choi, Hee-Kyu;Kim, Seong-Soo;Hwang, Jin-Yeon
    • Journal of the Mineralogical Society of Korea
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    • v.20 no.2 s.52
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    • pp.135-145
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    • 2007
  • The needs for the ultra fine particles have been increased in preparation field of raw powders such as fine ceramics and high functional products. In this study, a series of wet grinding experiments were carried out on inorganic powders such as calcite, pyrophyllite and talc by a stirred ball mill. The particle size distribution of ground products of each test material fur a given grinding time was found to be expressed by the grinding rate (selection function) which was obtained from the grinding kinetics analysis. The median diameter decreased from 6.49 to $0.47{\mu}m$ in calcite, and decreased from 3.91 to $1.14{\mu}m$ in pyrophyllite. However, in talc, median diameter was decreased a little bit from 10.30 to $6.67{\mu}m$. The grinding rate changing on calcite and pyriphyllite were similar at the same conditions. However, in the case of talc, it was observed that the grinding rate was not increased compared to other samples.

A study on the characteristic of grinding by spark-out (불꽃소멸에 의한 연삭특성에 관한 연구)

  • 이연종;김정두
    • Journal of the korean Society of Automotive Engineers
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    • v.15 no.3
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    • pp.120-125
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    • 1993
  • The surface roughness of workpiece is reduced during spark-out. The reduction of roughness is a benefit of spark-out, but spark-out lowers productivity. The characteristics of spark-out are different to those of plunge grinding to which feed is applied. This difference is due to overlapping cutting during spark-out. Effect of spark-out is in proportion to volume of grain wear. This phenomenon is due to different overlapping area. Dressing interval can be enlarged by spark-out, when volume of grain wear is large. In this study, the characteristic of spark-out was studied by spark-out obserbation in various grinding conditions. For this purpose thrust force, spark-out time and surface roughness of workpiece were experimentally investigated in various grinding conditions.

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Ultra-precision Free-form Surface Grinding of WC Core (초경 금형의 자유 곡면 초정밀 연삭)

  • Park, Soon-Sub;Hwang, Yeon;Kim, Geon-Hee;Won, Jong-Ho
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.5
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    • pp.64-71
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    • 2009
  • Cylindrical lens core for optical transceiver was designed and machined. With the lens design data, WC asymmetric core surface data were generated for non-revolutional ultra-precision grinding. Grinding process for optimum machining conditions of target surface was studied in terms of surface roughness and form profile. We used experimental results to optimize turbine speed, feed-rate and depth of cut with durable grinding wheel wear. Ground WC cores were measured contact type profilers and verified.

Surface Wheel Pattern Analysis and Grinding Process Parameters of Silicon (반도체 실리콘재료의 정밀연삭을 위한 공정변수와 연삭후 표면에 형성된 wheel pattern과의 관계)

  • Oh, Han-Seog;Park, Sung-Eun;Lee, Hong-Lim
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.2
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    • pp.187-194
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    • 2002
  • For the fine grinding process development of semiconductor monocrystalline silicon, wheel rotational speed, chuck rotational speed, feed rate and hysteresis force were controlled. Magic mirror system was used for grinding wheel pattern analysis. Curvature of wheel pattern was measured by fitting equation. The modeling of surface wheel pattern was related to wheel and chuck rotational speed. The calculated curvature of the model was well matched with the measured curvature. The statistical analysis indicated wheel and chuck rotational speed were significantly effective on.

A Study on Precision Infeed Grinding for the Silicon Wafer (실리콘 웨이퍼의 고정밀 단면 연삭에 관한 연구)

  • Ahn D.K.;Hwang J.Y.;Choi S.J.;Kwak C.Y.;Ha S.B.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1-5
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    • 2005
  • The grinding process is replacing lapping and etching process because significant cost savings and performance improvemnets is possible. This paper presents the experimental results of wafer grinding. A three-variable two-level full factorial design was employed to reveal the main effects as well as the interaction effects of three process parameters such as wheel rotational speed, chuck table rotational speed and feed rate on TTV and STIR of wafers. The chuck table rotaional speed was a significant factor and the interaction effects was significant. The ground wafer shape was affected by surface shape of chuck table.

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Grinding of WC-${Cr_3}{C_2}$-$Mo_2$$C-Ni Based Carbide (WC-${Cr_3}{C_2}$-$Mo_2$$C-Ni계 초경합금의 연삭)

    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.952-955
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    • 2002
  • $WC-3%(Cr_3C_2)-2%(Mo_2C)-12%Ni$ carbides were ground with three different types of electroplated diamond wheels with respect to grain friability. The grinding ratio in the case of the highest toughness grains, A becomes the highest at the workpiece speeds of 40 and 70mm/min exhibiting larger effect with smaller workpiece speed. The grinding ratio with the medium toughness grain is higher than that of grain A at higher workpiece speeds than 100mm/min. The surface roughness becomes smaller with increasing the grain friability The increasing rate on surface roughness with the increase of workpiece speed becomes higher with using the grain of lower friability.

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An Experimental Study on the Optimum Grinding of Alumina Ceramic Parts (알루미나 세라믹스 부품의 최적화 연삭 가공공정에 관한 기초적 연구 -기계적 특성 치에 의한 최적 가공 기법의 판명-)

  • 강재훈;김원일
    • Transactions of the Korean Society of Automotive Engineers
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    • v.1 no.2
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    • pp.103-116
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    • 1993
  • Recently, engineering ceramics called as the 3 material have been concerned significantly with some excellent mechanical properties and many functions as new materials for high precision mechanical components and engineering parts for at large. Then, for designing engineering parts using engineering ceramics, bending strength value data with high reliability is more essential than any other mechanical properties. But, because of brittleness and structural characteristic, it is very hard to grind with conventional tools, and the generation of cracks and various defects of engineering ceramics parts during grinding machining process are serious problems. Thus, in present study, surface grinding experiments with various machining conditions using resin bond diamond wheels are carried out to obtain the most excellent guality of testpiece surface and optimum step of grinding process for the high efficient stock removal rate to save running time. As the results from grinding experiments and 3-points bending strength test of ground Al2O3 ceramics parts on Korean Standard, manufactured in our country and Japan, basic technology and know-how to develop the optimum grinding machining conditions and also high bending strength values with high reliability are obtained.

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A Study on the Surface Grinding Machining Characteristics of FC200 Material (FC200 소재의 평면연삭 가공특성에 관한 연구)

  • Yang, Dong-Ho;Lee, Sang-Hyeop;Cha, Seung-Hwan;Lee, Jong-Chan
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.6
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    • pp.36-43
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    • 2022
  • Automobile brake discs are a major part of automobiles that are directly related to driver safety, and prevention of judder and squall noise is very important. This phenomenon occurs for complex reasons such as the precision and assembly of the brake module, and the material of the brake disc. The purpose of this study is to analyze the effect of the grinding wheel's grain size on the grinding conditions when machining cast iron, the material of the brake disc, and to derive the optimal grinding conditions through this.