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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
Journal Basic Information
Journal DOI :
The Korean Society of Tribologists and Lubrication Engineers
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Volume & Issues
Volume 23, Issue 6 - Dec 2007
Volume 23, Issue 5 - Oct 2007
Volume 23, Issue 4 - Aug 2007
Volume 23, Issue 3 - Jun 2007
Volume 23, Issue 2 - Apr 2007
Volume 23, Issue 1 - Feb 2007
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Contact Pressure Distribution of Pin Bushing Bearings Depending on the Friction Conditions
Kim, Chung-Kyun ; Kim, Do-Hyun ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 6, 2007, Pages 255~260
This paper presents the contact pressure distribution of pin bushing bearings for various lubrication friction modes such as oil film and elastohydrodynamic lubrication contacts, a mixed lubrication contact, a boundary contact, and a dry contact. During a sliding contact of a plain bearing, the boundary and dry rubbing contacts are dominated between a piston pin and a pin bushing bearing. This may come from a micro-scale clearance, an explosive impact pressures from the piston head, and an oscillatory motion of a pin bearing. The computed results show that as the oil film parameter
is increased from the dry rubbing contact to the oil film lubrication friction, the maximum oil film pressure is radically increased due to an increased viscous friction with a thin oil film thickness and the maximum asperity contact pressure is reduced due to a decreased asperity contact of the rubbing surfaces.
Gas Concentration of the Surface Modified TiC on the Tribological Properties
Bae, Heung-Taek ; Lim, Dae-Soon ; Na, Byung-Chul ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 6, 2007, Pages 261~265
Carbide-derived carbon coating has been synthesized by low temperature treatment of TiC disk with
mixture gases. A variety of physical measurements indicated that Ti was extracted and carbon layer was formed by exposure of
ratio increased with increasing
gas concentration. Wear coefficient and frictional coefficient varied with
gas concentration. When the
gas concentration decreased to 3.3 vol%, the friction coefficient approach a minimum. The results showed that degree of graphite crystallinity and variation of porosity due to the
gas content were responsible for different tribology performance.
The Brake Performance of Sintered Friction Materials Developed for High Speed Trains
Chung, So-La ; Hong, Ui-Seok ; Jang, Ho ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 6, 2007, Pages 266~271
The brake performance of sintered friction materials for the high speed train was studied. In this study, newly developed sintered materials based on copper were compared with the commercial products for high speed trains. They were tested on a 1/5 scale dynamometer using low carbon steel disks. Effectiveness, fade, and recovery tests were carried out to examine friction performance and the change of disk thickness variation (DTV) during brake applications and noise propensity were also evaluated. Results showed that the two sintered friction materials exhibit similar friction coefficients and braking performance, whereas the newly developed friction material was superior in terms of DTV generation and noise propensity to the commercial friction material. The improvement of the newly developed friction material was attributed to the high graphite content which reduced the stick-slip phenomena and prevented uneven disk wear by producing friction films on the counter disk.
Analysis of a Lip Seal Behavior for Rotary Union
Park, Tae-Jo ; Yoo, Jae-Chan ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 6, 2007, Pages 272~277
Various type of rotary unions are widely used to provide fluids between rotating parts. To prevent fluid leakage, most of the rotary unions adopt mechanical seals which is highly reliable but too expensive and complicate. In this paper, a simple lip seal system made of PTFE is adopted in designing of a compact rotary union. Using MARC, the behavior characteristics of lip seal are investigated for seal mounting process, and obtained variations of contact pressure distribution and contact width with interferences and fluid pressures. The results showed that contact width are increased with interference and pressure. The maximum contact pressure are also increased up to a certain interference and pressure, however, then decreased. The numerical methods and results can be applied in designing and performance improvement of lip seal adopted rotary union, and further extensive studies are required.
Effects of Steel Fiber, Zircon, and Cashew in the Brake Friction Materials on Creep Groan Phenomena
Jang, Ho ; Lee, Kang-Sun ; Lee, Eun-Ju ; Jeong, Geun-Joong ; Song, Hyun-Woo ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 6, 2007, Pages 278~282
Friction characteristics of a low-steel friction material were examined to investigate creep groan phenomena. The amount of three ingredients (steel fiber,
, cashew) were changed to produce test specimens using a constrained mixture design. Tribological properties of the friction material specimens were obtained by using a 1/5 scale dynamometer. Results showed that the amount of three different ingredients strongly affected the level of friction coefficient and the difference between the static friction coefficient and the kinetic friction coefficient
and steel fiber tended to increase the average friction coefficient and aggravated the stick-slip phenomena suggesting high creep groan propensity. On the other hand, cashew tended to decrease average friction coefficient and
Optimal Design of Passive Magnetic Bearings
Noh, Myoung-Gyu ; Yi, Ji-Eun ; Yoo, Seong-Yeol ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 6, 2007, Pages 283~287
Permanent-magnet (PM) passive bearings use the repulsive forces between the rotor and the stator magnets for the bearing function. It is desirable that the stiffness of the bearing is maximized with the given volume of the magnet. The stiffness is affected by the magnet strength, the number of layers, and the magnetization patterns. Previously, finite-element method (FEM) has been used to maximize the stiffness of the bearing. In this paper, we used the equivalent current sheet method to calculate the stiffness. The validity of this approach is checked against FEM results. The optimized bearing is applied to a micro flywheel energy storage system.
The Effect of Temperature on the Nano-scale Adhesion and Friction Behaviors of Thermoplastic Polymer Films
Kim, Kwang-Seop ; Ando, Yasuhisa ; Kim, Kyung-Woong ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 6, 2007, Pages 288~297
Adhesion and friction tests were carried out in order to investigate the effect of temperature on the tribological characteristics of poly (methylmethacrylate) (PMMA) film using AFM. The pull-off and friction forces on the PMMA film were measured under a high vacuum condition (below
Pa) as the temperature of the PMMA film was increased from 300 K to 420 K (heating) and decreased to 300K (cooling). Friction tests were also conducted in both high vacuum and air conditions at room temperature. When the temperature was 420 K, which is 25 K higher than the glass transition temperature
of PMMA, the PMMA film surface became deformable. Subsequently, the pull-off force was proportional to the maximum applied load during the pull-off force measurement. In contrast, when the temperature was under 395 K, the pull-off force showed no correlation to the maximum applied load. The friction force began to increase when the temperature rose above 370 K, which is 25 K lower than the
of PMMA, and rapidly increased at 420 K. Decrease of the PMMA film stiffness and plastic deformation of the PMMA film were observed at 420 K in force-displacement curves. After the heating to 420 K, the fiction coefficient was measured under the air condition at room temperature and was found to be lower than that measured before the heating. Additionally, the RMS roughness increased as a result of the heating.
The Tribological Behaviors of Mesoporous
Thin Film Formed by Sol-Gel and Self-Assembly Method
Lee, Young-Ze ; Shin, Yun-Ha ; Kim, Ji-Hoon ; Kim, Ji-Man ; Kim, Tae-Sung ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 6, 2007, Pages 298~300
Frictional characteristics of mesoporous
thin films were evaluated with different pore sizes. The films were manufactured by sol-gel and self-assembly methods to have a porous structure. The pores on the surface may play as the outlet of wear particle and the storage of lubricant so that the surface interactions could be improved. The pores were exposed on the surface by chemical mechanical polishing (CMP) or plasma-etching after forming the porous films. The ball-on-disk tests with mesoporous
thin films on glass specimen were conducted at sliding speed of 15 rpm and a load of 0.26 N. The results show considerable dependency of friction on pore size of mesoporous
thin films. The friction coefficient decreased as increasing the pore size. CMP process was very useful to expose the pores on the surface.
A Study on the Optimum Image Capture of Wear Particle for Condition Monitoring of Machine
Cho, Yon-Sang ; Park, Heung-Sik ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 6, 2007, Pages 301~305
The wear particle analysis has been known as very effective method to foreknow and decide a moving situation and a damage of machine parts by using the digital computer image processing. But it was not laid down and trusted to calculate shape parameters of wear particle and wear volume. In order to apply image processing method in the foreknowledge and decision of lubricated condition, it needs to verify the reliability of the calculated data by the image processing and to lay down the number of images and the amount of wear particle in one image. In this study, the lubricated friction experiment was carried out in order to establish the optimum image capture with the SM45C specimen under experiment condition. The wear particle data were calculated differently according to the number of image and the amount of wear particle in one image.
Experimental Study on Friction Characteristics of Pb-free Pin Bushing for an Internal Combustion Engine
Kim, Chung-Kyun ; Oh, Kyoung-Seok ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 6, 2007, Pages 306~311
This paper presents the friction characteristics of pb-fres pin bushing bearings for an automotive gasoline engine. The external load is 100 N to 600 N and the speed of the pin bushing bearing is 1000 rpm to 3000 rpm against the rubbing surfaces. And the contact modes of rubbing surfaces between a piston pin and a pb-free pin bushing specimen are a dry friction, an oil lubricated friction and a mixed friction that is starved by a lack of engine oil. Two influential factors of a contact rubbing modes and a material property are very important parameters on the tribological performance of a friction characteristic between a piston pin and a pb-free pin bushing. The experimental result shows that the pin bushing speed of 2000 rpm shows a typical oil film lubricated sliding contact mode in which means that as the applied load is increased, the friction loss is increasing. But other contact mode depending on the speed and the load may affect to the fiction coefficient without a regular and uniform trend. In summary, the oil lubricated rubbing surface definitely decreases a running-in period in short and increase oil film stiffness, and this may leads the reduction of a friction loss.
Estimation of Friction Characteristics of Wet-type Multiple Disc Brakes for Axle of 14 Ton Class Wheel Excavator
Cho, Yon-Snag ; Park, Heung-Sik ; Hong, Sung-Jin ; Choi, Byeung-Woon ; Bae, Myung-Ho ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 6, 2007, Pages 312~317
In general, a brake system of axle for heavy duty machine as a wheel excavator makes use of wet-type multiple disk brakes. These disk bakes are very important parts of heavy duty machine because they are advanced in durability and braking power, and can be designed compactly. Thus, we designed and made wet-type multiple disk brakes of axle for the 14ton class wheel excavator to be localization of these imported all. These disk brakes were made a comparative test with the existing disk brakes by the SAE No.2 dynamometer, and the friction characteristics as dynamic and static friction coefficient and wear depth of friction paper were measured.
Tribological Performance of Supper-A Dental Material
Choi, Won-Sik ; Kim, Won-Ku ; Kwon, Soon-Hong ; Chung, Sung-Won ; Kwon, Soon-Gu ; Park, Jong-Min ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 23, issue 6, 2007, Pages 318~322
The wear characteristics in supre-A dental material have been investigated. The wear tests were performed by using pin-on-disk wear tester at room temperature. Vickers hardness and fracture toughness measurement of dental materials were preformed. Microscopic observations on worn surfaces of specimens were conducted by SEM. The friction coefficient of supper-A material was investigated according to weight and slinging velocity. The hardness of supper-A material was a half of the enamel of natural teeth.