• Title/Summary/Keyword: Rmax/Ra

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A Study on the Surface Characteristics n the Alumina Grinding (알루미나 연삭표면 특성에 관한 연구)

  • 하상백
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1999.10a
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    • pp.519-524
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    • 1999
  • To manufacture alumina products, sintering and grinding process are needed. In Al2O3 grinding, macro/micro surface fracture and cracks are easily occurred on the ground surface because of its high brittleness. In view point of fatigue fracture, surface profile produced by grinding is considered as notches. Therefore, it was reasonable that magnitudes and shapes of surface profiles effects on fatigue strength and life. Particularly, surface finish of Al2O3 which have high hardness and brittleness have an effect on fatigue strength. In this paper, some experiments are carried out to examine influence of grinding conditions to magnitude and shape of surface profile as well as the relationships of Ra, Rmax, Rmax/Ra, and Ku. Through the experimental results, It is found that Ra and Rmax was affected by grinding conditions, but Rmax/Ra and Ku was not. There are linear relations between Ra and Rmax, and between Rmax/Ra and Ku.

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A Stlidy on the Mirror Surface F~n~shinSgy stem using Micro Abraslve Film (마이크로 필름을 이용한 경면가공 시스템에 관한 연구)

  • 김기수;남궁석
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1994.10a
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    • pp.273-278
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    • 1994
  • The surface finishing systems using the micro abrasive film were designed and manufactured to make the mirror surface of the cylindrical workpiece. An experimental study of surface finishing was carried out to investigate the performance of mirror surface finishing system. The surface roughness of stainless steel was about Rmax 0.2~0.25 .mu.m, Ra 0.02~0.04 .mu.m in abrasive grain size 12, 9 .mu.m. the surface roughness of chrome coated workpiece was about Rmax 0.07~ 0.11 .mu. m, Ra 0.01 in abrasive grain size 3 .mu. m. Also, to measure the mirror finishing time by mirror surface finishing system, the experiment was carried out on the chrome coated and ground roller of diameter 76mm and length 650mm. The finishing time and surface roughness were 40min and Rmax 0.1~0.13 .mu.m, Ra 0.01 .mu.m.

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A Study on the Cutting Characteristics of Al Alloy in End Milling for Various Hardnesses(I) (경도변화에 따른 Al합금의 밀링가공시 가공 특성에 관한 연구(I))

  • Kim Seong-Il
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.15 no.1
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    • pp.82-87
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    • 2006
  • The cutting tests of aluminum alloy with heat treatmented various hardnesses after rheo-fonning were carried out using CNC milling machine. The surface roughness(Ra, Rmax) of cut surface and cutting forces are measured at various cutting conditions such as low spindle speed, feed speed and hardness. In the CNC end-milling, the surface roughness increases as feed speed increases and decreases as spindle speed increases. However, the bulit-up edge has occurred on in case of low hardness and low feed speed. In experimental conditions, as the hardness of aluminum alloy increases, the surface roughness(Ra, Rmax) decreases

Surface polishing of Micro channel using Magneto-Rheological fluid (MR유체를 이용한 미세 채널구조물의 표면연마)

  • 이승환;김욱배;민병권;이상조
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1873-1876
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    • 2003
  • Magneto-rheological polishing is a new technology used in precision polishing. It utilizes magneto-rheological fluid. nonmagnetic polishing abrasive, aqueous carrier fluids in magnetic field to remove material from a part surface. Silicon micro channel as work piece is fixed in the slurry which is made of MR fluid and CeO$_2$(10 vol%) abrasive particles. And permanent magnet rotate in the slurry to transfers magnetic force to abrasive particles by increasing yield strength of MR fluid. so, the obtained bottom surface roughness of micro channel by experiment reduced to Ra 0.010 $\mu\textrm{m}$ Rmax 0.103 $\mu\textrm{m}$ and finwall surface roughness of micro channel reduced to Ra 0.018 $\mu\textrm{m}$ Rmax 0.468 $\mu\textrm{m}$. At optimum conditions of variables, the workpiece as silicon micro channel have about 24 times smaller surface roughness than before polishing.

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A Study on the Cutting Characteristics of AI in End Milling for Various Hardnesses (경도변화에 따른 Al의 밀링가공시 가공 특성에 관한 연구)

  • 김성일;이상진;김민호;김태영;이위로
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2004.10a
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    • pp.34-39
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    • 2004
  • The cutting tests of aluminum alloy for various hardnesses were carried out using CNC milling machine. The surface roughness{Ra, Rmax) of cut surface and cutting forces are measured at various cutting conditions such as spindle speed, feed speed and hardness. In the CNC end-milling, the surface roughness increases as feed speed increases and decreases as spindle speed increases. However, the bulit-up edge has occurred on in case of low hardness and low feed speed. In experimental conditions, as the hardness of aluminum alloy increases, the surface roughness(Ra, Rmax) decreases

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Comparison of Surface Roughness according to Porcelain Materials and Condensation (도재의 재료와 축성방법에 따른 표면거칠기의 비교)

  • Lee, Cheong-Hee
    • Journal of Dental Rehabilitation and Applied Science
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    • v.18 no.3
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    • pp.179-184
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    • 2002
  • To compare surface roughness in various porcelains and know effects of condensation, We used Ceramco dentin porcelain, Creation dentin porcelain, Creation margin porcelain, Vintage margin porcelain, Vintage dentin porcelain, and Vita dentin porcelain, and built up the powders with condensation or not, and then fired according to the instructions with porcelain furnace( Dekema, Germany ). We polished the samples step by step using the porcelain adjustment kit( Shofu Inc., Japan ), and then measured, compared and analysed Ra, Rz, and Rmax with Surftest SV-400( Mitutoyo Co., Japan ). 1. With condensation, roughness is significantly increased in Ceramco dentin porcelain (p<0.05) and decreased in Vita dentin porcelain(p<0.05). 2. In Ra, Vita dentin porcelain is significantly the roughest and Creation margin porcelain is rougher than others in no condensation, (p<0.05), and there is no difference under condensation. 3. In Rz, Vita dentin porcelain is significantly the roughest and Creation margin porcelain is rougher than others in no condensation, and Creation margin porcelain is significantly the roughest and Creation dentin porcelain is rougher than others under condensation(p<0.05). 4. In Rmax, Vintage dentin porcelain is significantly the roughest and Creation margin porcelain is rougher than others in no condensation, and Creation margin porcelain is significantly the roughest than others under condensation(p<0.05).

An Evaluation of Skiving Cutting Characteristics of TiCN PACVD Coating Caribide Hob (TiCN PACVD코팅 초경호브의 Skiving절삭특성 평가)

  • Cheon, Jong-Pil
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.2
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    • pp.471-477
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    • 2012
  • SCM420 steel tempered after performing gear hove PACVD carbide coating on the surface after the cutting surface hardness was high. Difficult-to-cut, without coating is classified as mild as large, including materials like mild, high strength that improves tool life and productivity have limited availability. Drive to improve it in the TiCN-coated carbide call for war to the finish coating on cutting a hob skiving good workability, tool wear less, 2.5-fold increase in tool life results were obtained. Experiments using CNC Skiving hobbing machine with wet cutting conditions, cutting speed and feed rate to apply a variety of the tool wear and surface roughness data were obtained. Results from condition 2 (V = 200m/min F = 0.7mm/rev) cutting speed feed mark the cutting surface microstructure and surface roughness Rmax $4.7{\mu}m$(Ra $1.19{\mu}m$) of the data was obtained.

ANALYSIS OF PORCELAIN SURFACE ROUGHNESS POLISHED BY VARIOUS TECHNIQUE (활택방법에 따른 도재표면의 거칠기 비교)

  • Lee, Kyu-Young;Lee, Chung-Hee;Jo, Kwang-Hun
    • The Journal of Korean Academy of Prosthodontics
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    • v.36 no.3
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    • pp.506-513
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    • 1998
  • This study was designed to compare the smoothness by glazing method with that by polishing method after 48 specimens of Ceramco II block, one of porcelain materials used for PFM, were baked according to the manufacturer's directions. The specimens were roughened with new green stone at 15,000rpm for 30 seconds and sandblasted with $25{\mu}$aluminum oxide for 15 seconds. They were divided into 4 groups at random, and 4 groups were prepared as follows : Group I : specimens were autoglazed and overpolished with polishing system. Group II : specimens were polished with only polishing system. Group III : specimens were glazed after adding glazing liquid, vitachrom 'L'-fluid (vita zahnfabrik co. Germany) to the rough surface Group V : specimens were just autoglazed Using the surface roughness tester, Ra, Rmax. and Rz were estimated 5 times per specimen, and recording process of mean value was repeated 3 times. The results were as follows : 1. The Ra of group I and group II was lower than group III and group IV (p<001). 2. There was lower value of Rz in group I and group II than group III and group IV (p<001). 3. The Rmax of group I (overpolished with polishing system after autoglazing) and group II (polished with only polishing system) was lower than group III (glazed after adding glazing liquid) and group IV (autoglazed) (p<001). 4. There was not a statistically significant difference between group I and II and between group III and IV (p>001). 5. The roughness was increase in order of group I, II, III, IV in SEM

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A Study on the Mirror Surface Finishing System Using Micro Abrasive Film (마이크로 연마 필름을 이용한 경면 가공 시스템에 관한 연구)

  • Kim, Hong-Bea;Kim, Ki-Soo;Namgung, Suk
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.10
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    • pp.68-74
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    • 1997
  • The surface finishing system using the micro abrasive film was designed and manufactured to make the mirror surface of the cylindrical workpices. An experimental study of srface finishing was carried out to investigate the performance of mirror surface finishing system. The surface roughness value of stainless steel was about 0.2 .approx. 0.25 .mu. m Rmax, 0.02 .approx. 0.04 .mu. m Ra, using abrasive grain size of 12, 9 .mu. m. The surface roughness value of chrome coated workpiece was about 0.07 .approx. 0.11 .mu. m Ra using abrasive grain size 3 .mu. m. In the same condition, the chrome coated workpiece has obtained better surface roughness charateristics than the one of stainless steel.

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A Study on the Effect of Tip Radius of Diamond Stylus Machined by Ion Sputter in Surface Roughness Measurement (이온스파터 가공한 다이아몬드 촉침의 선단반경이 표면거칠기 측정에 미치는 영향)

  • Han, Eung-Gyo;No, Byeong-Ok;Yu, Yeong-Deok
    • Journal of the Korean Society for Precision Engineering
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    • v.7 no.3
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    • pp.37-47
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    • 1990
  • In accordance with the high precision of mechanical elements, it has been required to high precision in surface roughness measurement and, therefore, stylus tip radius is manufa- ctured less than 2 .mu. m through ion sputter machining. In this experiment, by suing ion sputter machined stylus pf fine tip, radius and lapping machined stylus, surface roughness of standard specimens, silicon wafer were measured and then Rmax, Ra, RMS value were investi- gatedaccording to the variation of tip radius of stylus. As a result, measuring error due to the variation of stylus tip radius in surface roughness measurement was decreased by using ion sputter machined stylus and also the measuring accuracy was improved. And the measuring variation of Ra, RMS calculated from correlation coefficient lager than 0.9 on the wave of short period and amplitude using ion sputter machined stylus of fine tip radius.

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