• Title/Summary/Keyword: Average Surface Roughness

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An Estimation of Surface Roughness from the AE Signal in Surface Grinding (평면연삭시 AE 신호에 의한 표면거칠기 예측)

  • 송지복;이재경;곽재섭;이종렬
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.115-119
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    • 1996
  • An estimation of surface roughness value is a very important and difficult issue in grinding process. The definition of the D.A.R.F(Dimensionless Average Roughness Factor) has been made including the absolute average and tile standard deviation that are the parameters of the AE(Acoustic Emission) sign. The theoretical equation of the surface roughness applying the D.A.R.F has been derived from the regressive analysis and specified with respect to the availability through the experimental approach on the machine.

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Alteration of Hydroxyapatite Surface after Tooth Bleaching with Nonthermal Atmospheric Pressure Plasma

  • Nam, Seoul Hee;Lee, Hae June;Hong, Jin Woo;Kim, Gyoo Cheon
    • International Journal of Oral Biology
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    • v.39 no.4
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    • pp.187-192
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    • 2014
  • Nonthermal atmospheric pressure plasma has attracted great interest for biomedical applications. The plasma consists of charged particles, radicals, and a strong electric field as the fourth state of matter. This study evaluated the change in the surface roughness after tooth bleaching by plasma in combination with a low concentration (15%) of carbamide peroxide, specifically whether the application of plasma produced detriments, such as demineralization and structural change, with the goal of efficient and safe tooth bleaching. After being combined with plasma and 15% carbamide peroxide, the hydroxyapatite surface was significantly smoother with a low roughness average value. Tooth bleaching with 15% carbamide peroxide alone produced an irregular surface and increased the surface roughness with high roughness average value. Tooth bleaching with plasma resulted in no significant variations in hydroxyapatite in terms of change in surface roughness and surface topography. The application of tooth bleaching with plasma is not deleterious to dental hard tissue, implicating it as a safe tooth bleaching technique.

Relation between Surface degradation and Anti-pollution Characteristics in RTV Silicone Rubber (RTV 실리콘 고무의 표면열화와 내오손 특성과의 상관관계)

  • 연복희;이태호;허창수;이상엽
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.7
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    • pp.598-606
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    • 2000
  • In this paper we investigated the relation between the surface degradations and anti-pollution characteristics of Room Temperature Vulcanized(RTV) silicone rubber coating that has different roughness through immersing into saline water. We utilized several analytic techniques such as atomic force microscopy(AFM) scaning electron microscopy(SEM) contact angle Salt Deposit Density(SDD) and average leakage current under the condition of salt fog. It is found that the surface roughness of treated RTV silicone rubber increased and the hydrophobicity of sample surface decreased with increasing the duration o immersion into water due to the erosion of base polymer the melting down alumina trihydrate(ATH) and the diffusion of Low Molecular weight(LMW) fluid. Despite the roughness of surface had been increased by water immersion excellant anti-pollution and recovery characteristics were maintained and SDD saturated to 0.1~0.14mg/cm$^2$. The average leakage current under salt fog increased with surface roughness. Measurement of average leakage current will be helpful to investigate surface degradation and lifetime expectation of RTV silicone coating.

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Effects of Nanopowder Additives in Micro-electrical Discharge Machining

  • Tan, Peng-Cheong;Yeo, Swee-Hock;Tan, Yie-Voon
    • International Journal of Precision Engineering and Manufacturing
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    • v.9 no.3
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    • pp.22-26
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    • 2008
  • The use of electrical discharge machining (EDM) for micro-machining applications requires particular attention to the machined surface roughness and discharge gap distance, as these factors affect the geometrical accuracy of micro-parts. Previous studies of conventional EDM have shown that selected types of semi-conductive and non-conductive powder suspended in the dielectric reduced the surface roughness while ensuring a limited increase in the gap distance. Based on this, an extension of the technique to micro-EDM was studied Such work is necessary since the introduction of nanopowders suspended in the dielectric is not well understood. The experimental results showed that a statistically significant reduction in the surface roughness value was achieved at particular concentrations of the powder additives, depending on the powder material and the machining input energy setting. The average reduction in surface roughness using a powder suspended dielectric was between 14-24% of the average surface roughness generated using a pure dielectric. Furthermore, when these additive concentrations were used for machining, no adverse increase in the gap distance was observed.

Surface roughness prediction with a full factorial design in turning (완전요인계획에 의한 선삭가공시 표면거칠기 예측)

  • Yang, Seung-Han;Lee, Young-Moon;Bae, Byong-Jung
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.1 no.1
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    • pp.133-140
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    • 2002
  • The object of this paper is to predict the surface roughness using the experiment equation of surface roughness, which is developed with a full factorial design in turning. $3^3$ full factorial design has been used to study main and interaction effects of main cutting parameters such as cutting speed, feed rate, and depth of cut, on surface roughness. For prediction of surface roughness, the arithmetic average (Ra) is used, and stepwise regression has been used to check the significance of all effects of cutting parameters. Using the result of these, the experimental equation of surface roughness, which consists of significant effects of cutting parameters, has been developed. The coefficient of determination of this equation is 0.9908. And the prediction ability of this equation was verified by additional experiments. The result of that, the coefficient of determination is 0.9718.

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A Study on Surface Roughness in Circular Pocket Machining of SCM415 Steel (SCM415강의 원형포켓 가공시 표면 거칠기에 관한 연구)

  • Choi, Chul-Woong
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.18 no.7
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    • pp.77-82
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    • 2019
  • In this study, we study the change of surface roughness during cutting machining by changing the cutting conditions such as feed rate and spindle velocity with chromium molybdenum steel (SCM415) material and TiCN and TiAlN coated end mill tools. The surface roughness value of the test specimen for SCM415, was found to be 3,000 rpm in TiCN coated end mill and $0.634{\mu}m$ in surface roughness at a feed rate of 100 mm/min. In the TiAlN coated end mill, 300 mm/min, the surface roughness was the best at $0.699{\mu}m$. The overall average surface roughness of each coating tool was better than that of TiAlN.

Influence of Surface Roughness on Morphology of Aluminum Alloy After Pulsed-Laser Irradiation (펄스 레이저 조사 후 알루미늄 합금의 표면상태에 대한 표면 거칠기의 영향)

  • Choi, Sung-Ho;Kim, Chung-Seok;Jhang, Kyung-Young;Shin, Wan-Soon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.9
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    • pp.1105-1111
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    • 2011
  • The objective of this study is to investigate the influence of surface roughness on the morphology of aluminum 6061-T6 alloy after irradiation with a Nd:YAG pulsed laser. The test specimen was prepared by a polishing process using a diamond paste ($1{\mu}m$) and emery polishing papers (#100, #220, #600, #2400) to obtain different initial surface roughness. After irradiation with ten pulsed-laser shots, the surface morphology was examined by using scanning electron microscopy (SEM), optical microscopy (OM), and atomic force microscopy (AFM). The diameter of the melted zone increased with the surface roughness because the multiple reflections and absorption of the laser beam occurred on the surface because of the surface roughness, so that the absorptance of the laser beam changed. This result was verified using the relative absorptance calculated from the diameter of the melted zone with the surface roughness and the diameter increased with the average surface roughness.

Observation of machining and polishing according to the dental barrel polishing time (치과용 바렐연마의 시간에 따른 가공도 및 연마도 관찰)

  • Hyeon-jeong Ko;Sung-min Choi
    • Journal of Technologic Dentistry
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    • v.45 no.4
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    • pp.87-94
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    • 2023
  • Purpose: This study aimed to observed changes in the shape of dental barrels based on application time. Machinability measures the angle of alloy specimens. Polishing performance measures the surface roughness of alloy specimens. Methods: The dental barrel polishing equipment used in this study was a Snow Barrel (DK Mungyo). Three types of cobalt-chromium alloys for partial dentures were used as specimens (BC CAST R [BP]; Bukwang, Vera PDI [VP]; Aalbadent, and GM 800+ [GP]; Dentaurum). Specimens were prepared in the form of plates (10 mmx10 mmx2 mm). Dental barrel polishing was performed at 450 rpm for 60 minutes with intervals of 5 minutes. The processing angle was measured using a microscope (SZ61; Olympus). Results: For the angle measurement, the VPC specimen was measured at 78.64°, 36.00° for the VP60 specimen, 79.57° for the BP control (BPC) specimen, 28.07° for the BP60 specimen, 75.01° for the GPC specimen, and 39.92° for the GP60 specimen. For the surface roughness measurements, the average surface roughness of the VPC and VP15 specimens were 1.09 ㎛ and 0.26 ㎛, respectively. The average surface roughness of the BPC and BP20 specimens were 1.77 ㎛ and 0.29 ㎛, respectively. The average surface roughness of the GPC and GP15 specimens were 1.08 ㎛ and 0.27 ㎛. Conclusion: The results were excellent after about 20 minutes of dental barrel polishing conditions presented in this study.

A study on lubrication Properties of a Dimple Pattern using an Average Flow Analysis with a Contact Model of Asperities (돌기 접촉 모델과 평균 유동 분석을 이용한 딤플 패턴의 윤활 특성에 관한 연구)

  • Kim, Mi-Ru;Lee, Seung-Jun;Li, Liang;Lee, Deug-Woo
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.15 no.6
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    • pp.41-49
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    • 2016
  • To evaluate lubrication properties by surface roughness under boundary and mixed lubrication, a new approach is suggested by both asperity flow and contact with stochastic characteristics. Many researchers already have studied the effect of surface roughness on flow. But, it has become important to research of the phenomenon of asperities contact in surfaces because the growth of asperities contact area under heavy load conditions. In this paper, flow factors in the average flow model derived by Patir and Cheng were used, and a multi-asperity contact model was included to calculate lubrication properties of a surface with a randomly generated rough surface. A numerical analysis using the average Reynolds equation with both the average flow model and the asperity contact model was conducted, and the results were compared with those from previous research. The results showed that the influence of asperities on lubrication and the friction coefficient changed rapidly on application of contact model.

Surface Roughness Effects on the Lubrication Characteristics of the Engine Piston Ring Pack

  • Yun, Jeong-Eui
    • KSTLE International Journal
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    • v.1 no.2
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    • pp.83-90
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    • 2000
  • The surface roughness between a piston ring pack and a cylinder liner directly affects the fuel economy, the oil consumption, and the emission of the engine so that it is very important to clarify the surface roughness effects on the lubrication characteristics. The friction characteristics of the piston ring during engine operations are known to as mixed lubrication experimentally. In this study to simulate the effects of the surface roughness of the piston ring pack on the lubrication characteristics, the mixed lubrication analysis of piston rings was performed using the simplified average Reynolds equation. From the results the surface roughness was found be considerably affects minimum oil film thickness as well as FMEP(Friction Mean Effective Pressure). Especially, the oil ring was the most sensitive on the surface roughness.

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