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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Tribologists and Lubrication Engineers
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Journal DOI :
The Korean Society of Tribologists and Lubrication Engineers
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Volume & Issues
Volume 27, Issue 6 - Dec 2011
Volume 27, Issue 5 - Oct 2011
Volume 27, Issue 4 - Aug 2011
Volume 27, Issue 3 - Jun 2011
Volume 27, Issue 2 - Apr 2011
Volume 27, Issue 1 - Feb 2011
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Effect of Surface Roughness of Counterface on Tribological Characteristics of PTFE and UHMWPE
Dong, Sun ; Chung, Koo-Hyun ; Lee, Kyung-Sick ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 27, issue 6, 2011, Pages 293~301
DOI : 10.9725/kstle.2011.27.6.293
Understanding of the tribological characteristics of polytetrafluoroethylen (PTFE) and ultra-high-molecular-weight polyethylene (UHMWPE) is crucial for their applications such as bearing and total joint replacement. In this work, the effect of the surface roughness of carbon steel on the tribological behaviors of PTFE and UHMWPE was experimentally investigated by using block-on-ring tribotester with friction force monitoring capability. It was found that that the amount of material transfer layers of PTFE formed on the carbon steel was significantly larger than those of UHMWPE, which was responsible the lower friction coefficient of PTFE. It was also concluded that the effect of surface roughness of carbon steel on the friction coefficient of UHMWPE was more significant than that of PTFE. For UHMWPE, it was found that the effect of surface roughness of counterface was varied with respect to applied normal force and sliding as well. Based on Archard's wear law, the wear coefficient of PTFE and UHMWPE was calculated to be
Lubrication Characteristics of Laser Textured Parallel Thrust Bearing : Part 3 - Effect of Number of Dimples
Park, Tae-Jo ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 27, issue 6, 2011, Pages 302~307
DOI : 10.9725/kstle.2011.27.6.302
Laser surface texturing (LST) methods are widely applied recently to reduce friction and improve reliability of machine components such as thrust bearings, mechanical face seals and piston rings, etc. In this paper, numerical analysis is carried out to investigate the effect of number of dimples on the lubrication characteristics of parallel thrust bearing using a commercial computational fluid dynamics (CFD) code, FLUENT. Pressure distributions of present analysis are physically consistent than those obtained from numerical analysis of Reynolds equation. The overall lubrication characteristics are highly affected by number of dimples and their locations. The results can be use in design of optimum dimple characteristics to improve thrust bearing performance and further researches are required.
Friction Characteristics of DLC and WC/C
Kim, Dong-Wook ; Kim, Kyung-Woong ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 27, issue 6, 2011, Pages 308~313
DOI : 10.9725/kstle.2011.27.6.308
In this study, friction tests were performed in order to investigate the effect of sliding velocity and normal load on the friction characteristics of DLC (a-C:H) and WC/C (a-C:H:W) using a ball-on-disk type friction tester. DLC and WC/C were deposited on AISI 52100 steel balls. Friction tests against carburized SCM 415 Cr-Mo steel disks were carried out under various sliding velocity (0.1, 0.78, 1.56, 3.13, 6.25, 12.5, 25, 50 and 100 mm/s) and normal load (2.4, 4.8 and 9.6 N) conditions while the relative humidity was 20~40 % R.H. and air temperature was
. As results, kinetic friction coefficients of DLC and WC/C were obtained under each test condition. The results show that the kinetic friction coefficients of DLC and WC/C generally increase with the increase in sliding velocity. And, under the same sliding velocity condition, the kinetic friction coefficients are almost constant regardless of normal load. In addition, the kinetic friction coefficients of DLC are lower than those of WC/C under the same test conditions.
A Study on Models for the Analysis of Pressure Pulsation in a Swash-Plate Type Axial Piston Pump
Shin, Jung-Hun ; Kim, Hyoung-Eui ; Kim, Kyung-Woong ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 27, issue 6, 2011, Pages 314~320
DOI : 10.9725/kstle.2011.27.6.314
Although swash-plate type axial piston pumps have the merits of wide operating conditions and high efficiency, the characteristics of pressure pulsation and flow ripple which result in system noise generation are on-going problems. This research examined the analytic models of the dynamic oil pressure and flow characteristics in the pump. A new mathematical model which considered the pressure behaviors of each cylinder and discharge piping was developed to analyze the pump pressure and flow. This model also considered the leakages in the clearances which many researchers have ignored so far. Using the developed model, numerical calculations were implemented. The results showed that widely used simple model which considered only a single cylinder can not predict actual discrete flow dynamics and that fluid inertia effect has to be considered in the mathematical model. Several critical parameters were discussed such as port volume and discharge resistance on the assumption that the pipe length is not so long. The effect of leakages was studied on the final stage.
Tribological Characteristics of Paraffin Liquid Oil with Nanodiamond and Effects of Surface Hardness on Wear Properties
Lee, Gyu-Sun ; Kim, Hyun-Soo ; Lee, Jeong-Hoon ; Park, Tae-Hee ; Lee, Jung-Suk ; Lee, Young-Ze ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 27, issue 6, 2011, Pages 321~325
DOI : 10.9725/kstle.2011.27.6.321
Nanodiamond was dispersed in paraffin liquid oil to investigate the effects of nanodiamond at the marginally lubricated condition. Scuffing test and immediate loading sliding wear test were conducted using the fabricated nanodiamond oil. As a result, dispersion of nanodiamond in oil leads to increase in scuffing life, and nanodiamond contents affects the scuffing life. In case of immediate loading sliding wear test, the result was different according to hardness of specimen. If hardness of specimen was low, abrasion of nanodiamond occurred actively. If hardness of specimen was increased, however, nanodiamond can act as a spacer or rolling between contacting surfaces.
EHL Analysis of Ball Bearing for Rough Surface With the FlowFactor
Lee, Byung-Wook ; Moon, Seok-Man ; Kim, Tae-Wan ; Cho, Yong-Joo ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 27, issue 6, 2011, Pages 326~331
DOI : 10.9725/kstle.2011.27.6.326
The purpose of this paper is to analyze and discuss the effects of surface roughness by comparing the elastohydrodynamic lubrication(EHL) analysis of smooth surface and rough surface as the ball bearing. In order to do this, The average flow model is adapted for the interaction of the flow rheology of lubricant and surface roughness. The average Reynolds equation and the related flow factor which describes the coupled effects of surface roughness and flow rheology, the viscosity-pressure and density-pressure relations equations, the elastic deformation equation, and the force balance equation are solved simultaneously. The results show that effects of surface roughness on the film thickness and pressre distribution should be considered especially in EHL contact problems.
An Experimental Study of Vibrator Amplitude Change for a Clamping Force Dispersion and Friction Coefficient Decrease
Lee, Geum-Gang ; Moon, Seok-Man ; Cho, Yong-Joo ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 27, issue 6, 2011, Pages 332~337
DOI : 10.9725/kstle.2011.27.6.332
The object of this experimental study is to investigate influences of vibrator amplitude on clamping force in vibration for bolted joint. The experiment is that change the vibrator amplitude to check clamping force. also the friction coefficient calculated by equation to use an obtained in experiments. The main purpose of generation vibrations is decreasing the clamping force dispersion. also If vibration occurs while tightening the bolt is reduced coefficient of friction. In this paper, In experiments to measure the clamping force before vibrator's amplitude changing. Vibrator's amplitude changes to 5.5mm from 4.4mm. As a result, under various vibration condition, relationship of clamping force and Vibrator amplitude.
Lubrication Characteristics of Laser Textured Parallel Thrust Bearing : Part 4 - Effect of Dimple Shape
Park, Tae-Jo ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 27, issue 6, 2011, Pages 338~343
DOI : 10.9725/kstle.2011.27.6.338
Laser surface texturing (LST) methods are widely applied now to reduce friction and improve reliability of machine components such as thrust bearings, mechanical face seals and piston rings, etc. In this paper, the effect of dimple shapes on the lubrication characteristics of parallel thrust bearing are studied using a commercial computational fluid dynamics (CFD) code, FLUENT. Pressure and streamline distributions, variations of supporting load, leakage flow rate and friction force, are compared for three different dimple sectional shapes such as circle, pyramid and rectangle type. The lubrication characteristics are highly affected by dimple shapes and number of dimples. The pyramid type dimple shape can support the highest load while the rectangle type is the best in friction reduction.
Tribological Properties of Tungsten Oxide Nanorods
Kim, Dae-Hyun ; Hahn, Jun-Hee ; Song, Jae-Yong ; Ahn, Hyo-Sok ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 27, issue 6, 2011, Pages 344~350
DOI : 10.9725/kstle.2011.27.6.344
Friction and wear behavior of tungsten oxide nanorods (TONs) was investigated using friction force microscopy(FFM) employing colloidal probes instead of conventional sharp tips. Vertically well-ordered TONs with 40 nm diameter, 130 nm length and 100 nm pitch width were synthesized on an anodic aluminium oxide substrate using two step electrochemical anodizing processes. The colloidal probe (diameter 20
) attached at the free end of tipless cantilever was oscillated(scanned) against a stationary surface of vertically aligned TONs with various scan speeds (1.2
) and sliding cycles (100, 200 and 400) under normal load of 800 nN. The friction force and wear depth decreased with the increase of the scan speed. Plastically deformed thin layers were formed and sparsely deposited on the worn nonorod surface. The lower wear rate of the TONs with the longer oscillating cycles was attributed to the decreased real contact pressure due to the increase of real contact area between the colloidal probe and the TONs.
Wear Behavior of Al/SiC Composites Fabricated by Thermal Spray Process (1) - Effect of Sliding Speed on Wear Behavior -
Lee, Kwang-Jin ; Kim, Kyun-Tak ; Kim, Yeong-Sik ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 27, issue 6, 2011, Pages 351~355
DOI : 10.9725/kstle.2011.27.6.351
Al/SiC composites were fabricated by thermal spray process, and the dry sliding wear tests were performed using the various sliding speed of 10, 30, 60 and 90 RPM through 1000 cycles. The applied load was 10 N and radius of wear track was 15 mm. Wear tracks on the Al/SiC composites were investigated using scanning electron microscope(SEM) and energy dispersive X-ray spectroscopy (EDS). In the case of sliding speed of 10 RPM, adhesive wear behavior caused by plastic deformation of composits surface was observed. In the cases of sliding speed of 30, 60, 90 RPM, abrasive wear behavior on the adhered layer formed by debris were observed. Through this study, it was found that the wear behavior of Al/SiC composites was mainly influenced by the sliding speed.