• Title/Summary/Keyword: Laser-texturing

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Lubrication Characteristics of Laser Textured Parallel Thrust Bearing : Part 2 - Effect of Dimple Location (Laser Texturing한 평행 스러스트 베어링의 윤활특성 : 제2보 - 딤플 위치의 영향)

  • Park, Tae-Jo;Hwang, Yun-Geon
    • Tribology and Lubricants
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    • v.26 no.1
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    • pp.1-6
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    • 2010
  • In the last decade, laser surface texturing (LST) has emerged as a viable option of surface engineering. Many problems related with mechanical components such as thrust bearings, mechanical face seals and piston rings, etc, LST result in significant improvement in load capacity, wear resistance and reduction in friction force. It is mainly experimentally reported the micro-dimpled bearing surfaces can reduce friction force, however, precise theoretical results are not presented until now. In this paper, a commercial computational fluid dynamics(CFD) code, FLUENT is used to investigate the lubrication characteristics of a parallel thrust bearing having 3-dimensional micro-dimple. The results show that the pressure, velocity and density distributions are highly affected by the location and number of dimple. The numerical method and results can be use in design of optimum dimple characteristics, and further researches are required.

Lubrication Characteristics of Laser Textured Parallel Thrust Bearing : Part 3 - Effect of Number of Dimples (Laser Texturing한 평행 스러스트 베어링의 윤활특성 : 제3보 - 딤플 수의 영향)

  • Park, Tae-Jo
    • Tribology and Lubricants
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    • v.27 no.6
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    • pp.302-307
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    • 2011
  • 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.

Lubrication Characteristics of Laser Textured Parallel Thrust Bearing : Part 4 - Effect of Dimple Shape (Laser Texturing한 평행 스러스트 베어링의 윤활특성 : 제4보 - 딤플 형상의 영향)

  • Park, Tae-Jo
    • Tribology and Lubricants
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    • v.27 no.6
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    • pp.338-343
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    • 2011
  • 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.

Sliding Friction Properties of Laser Surface Dimple Patterned on PMMA under Saline Lubricated (레이저 표면 딤플 패턴된 PMMA 소재 표면의 식염수 윤활 하에서의 미끄럼 마찰특성)

  • Dongho Hyun;Younghun Chae;Da-I Jung
    • Tribology and Lubricants
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    • v.39 no.4
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    • pp.148-153
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    • 2023
  • Laser surface dimple patterning is a method of laser surface texturing to reduce lubrication sliding friction. The dimple pattern improves friction properties by reserving lubricant and trapping worn particles. This surface texturing technology can reduce coefficients of friction and extend the service life by applying a uniform load to the surface of the material. This study investigates the friction properties using PMMA, a highly compatible polymer material, as a specimen. We observe the friction properties of untextured specimens by processing specimens with dimple pattern densities of 5 and 10 on the surface area using laser. Dimple pattern density affects the coefficient of friction. We present the following friction property results using a pin-on-disc sliding friction test under saline lubrication. The coefficients of friction for the dimple patterned specimens are lower than those for the untextured specimens. As the normal load and sliding speed increase, the coefficients of friction of the dimple pattern specimens decrease differently from those of the untextured specimens. The specimen with a dimple pattern density of 5 at a normal load of 24.5 N and a sliding speed of 0.22 m/s has the best friction properties. Notably, different friction properties are exhibited depending on the dimple pattern densities.

Lubrication Characteristics of Laser Textured Parallel Thrust Bearing: Part 1 - Effect of Dimple Depth (Laser Texturing한 평행 스러스트 베어링의 윤활특성 : 제1보 - 딤플깊이의 영향)

  • Park, Tae-Jo;Hwang, Yun-Geon
    • Tribology and Lubricants
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    • v.25 no.5
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    • pp.305-310
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    • 2009
  • Laser surface texturing (LST) methods are applied recently to generate micro-dimples in machine components having parallel sliding surfaces such as thrust bearings, mechanical face seals and piston rings, etc. And it is experimentally reported by several researchers that the micro-dimpled bearing surfaces can reduce friction force. Until now, however, theoretical results for various dimple parameters are not fully presented. In this paper, a commercial computational fluid dynamics (CFD) code, FLUENT is used to investigate the effect of dimple depth on the lubrication characteristics of parallel thrust bearing. The results show that the pressure, velocity and density distributions within dimples are highly affected by dimple depths and cavitation conditions. Adoption of micro-dimple on the bearing surface can reduce the friction force highly and its levels are affected by dimple depth. The numerical methods and results can be use in design of optimum dimple characteristics to improve thrust bearing performance.

The Effect of Surface Micro Texturing on Friction and Wear of Polyoxymethylene (POM 마찰 및 마모에 대한 마이크로 표면 텍스처링의 영향)

  • Lee, Jae-Bong;Cho, Min-Haeng
    • Tribology and Lubricants
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    • v.25 no.3
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    • pp.141-149
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    • 2009
  • The effect of micro-cavities fabricated using laser surface texturing (LST) technique on polyoxymethylene (POM) surface was studied in terms of heat affected zone (HAZ), cavity geometry, surface roughness, deformation of cavity along with sliding cycles, and tribological characteristics. Cavity process parameters were lamp current, process time, and the stream of air used to minimize the flow of molten polymer into cavity. Especially, the deformation of cavity geometry was extensively studied to provide deep insight into morphological analysis of the cavities. Also, this paper presents the behavior of friction and wear of POM specimens as a function of sliding cycles.

Improvement of Tribological Characteristics of Multi-Scale Laser-Textured Surface in terms of Lubrication Regime (윤활영역에서 멀티크기 Laser Surface Texturing 효과)

  • Kim, Jong-Hyoung;Choi, Si Geun;Segu, Dawit Zenebe;Jung, Yong-Sub;Kim, Seock-Sam
    • Tribology and Lubricants
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    • v.30 no.1
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    • pp.59-63
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    • 2014
  • Laser Surface Texturing(LST) is a surface engineering process used to improve tribological characteristics of materials by creating patterned microstructures on the mechanical contact surface. In LST technology, a pulsated laser beam is used to create arranged dimples on a surface by a material ablation process, which can improve such as load capacity, wear resistances, lubrication lifetime, and reduce friction coefficients. In the present study, the effect of multi-scale LST on lubricant regime was investigated. A pulsed Nd:YAG laser was applied on the bearing steel(AISI 52100) to create arranged dimples. To optimize the surface texturing effect on friction, multi-scale texture dimples with some specific formula arrays were fabricated by combining circles, ellipses and the laser ablation process. The tribological testing of multi-scale textured surface was performed by a flat-on-flat unidirectional tribometer under lubrication and the results compared with that of the non-textured surface. Through an increase in sliding speed, the beneficial effect of multi-scale LST performance was achieved. The multi-scale textured surface had lower friction coefficient performances than the non-textured surface due to the hydrodynamic lubrication effect.

Simulation of laser zone texturing of Ni-P disk substrates by PLIC method (PLIC 방법을 사용한 Ni-P 디스크의 레이저 존 텍스처링 모사)

  • Kim, Heon-Joon;Ha, Eung-Ji;Kim, Woo-Seung
    • Proceedings of the KSME Conference
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    • 2000.11b
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    • pp.255-260
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    • 2000
  • Laser zone texture technology is widely used to enhance the tribological performance of high areal density media. This work investigates the transient process of melting and microscale surface deformation upon pulsed laser heating of Ni-P hard disk substrates by PLIC(Piecewise Linear Interface Calculation) method. The present results are compared with both the experimental and the Donor-Acceptor method results. It is found that the results from PLIC method are better than those of Donor-Acceptor method and they are in good agreements with the experimental results.

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