The Effect of Triangle-Shaped Surface Textures on the Performance of the Lubricated Point-Contacts

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Wen-zhong Wang ◽  
Zhixiang Huang ◽  
Dian Shen ◽  
Lingjia Kong ◽  
Shanshan Li
Keyword(s):  
Friction Coefficient ◽  
Electrical Contact ◽  
Tribological Performance ◽  
Operating Conditions ◽  
Friction Reduction ◽  
Point Contacts ◽  
Electrical Contact Resistance ◽  
Coverage Ratio ◽  
Lubrication Regimes ◽  
Ratio Size

It has been recognized that purposefully designed surface texturing can contribute to the improvement of tribological performance of elements and friction reduction. However, its optimal parameters may depend on the operating conditions. This paper investigated the effect of a triangle-shaped dimples array on the tribological performance of the lubricated point-contacts under different lubrication regimes, based on the rotational sliding experiment of a patterned steel disk against smooth steel balls. The dimples arrays were produced by laser process and characterized by the 3D profilometer. A series of tests were conducted with different dimple parameters including depth, coverage ratio, size, and direction. Stribecklike curves were obtained to depict the transition of lubrication regimes, and the electrical contact resistance was utilized to qualitatively characterize the lubrication status. The test results showed that the dimples arrays with different sizes, depths and coverage ratios had a distinct effect on the friction behaviors. Compared with the nontextured surfaces, when the dimple depth decreased from 30μm to zero with fixed coverage ratio and size, the friction coefficient firstly decreased, and then increased. The friction coefficient finally approached that of the nontextured surface, during which the lowest value appeared at the dimple depth of approximately 10∼15μm. The coverage ratio of texture showed the similar effect on the friction coefficient. Usually, the coverage ratio of approximately 10% resulted in the lowest friction coefficient. The dimple size and direction also had obvious effects on the friction coefficient. Thus, it can be concluded that there exists a set of optimal values for the dimple depth, coverage ratio, size, and direction to realize the friction reduction.

Effects of Temperature Rise of Grease on Lubricating Performance of Drive Elements under the Extreme Pressure

2021 ◽  
Vol 901 ◽  
pp. 187-192
Author(s):  
Yuh Ping Chang ◽  
Li Ming Chu ◽  
Hsiang Yu Wang ◽  
Chien Te Liu ◽  
Qi Wen Chen
Keyword(s):  
Friction Coefficient ◽  
Temperature Rise ◽  
Electrical Contact ◽  
Load Condition ◽  
Extreme Pressure ◽  
Electrical Contact Resistance ◽  
Heavy Load ◽  
Key Technology ◽  
Effects Of Temperature ◽  
Great Stress

To transfer more power and use it in a heavy load environment, the contact surface between the ball and the track must bear great stress. The temperature always rises due to friction, which is more likely to cause problems of material deformation and fatigue failure. As a result, it will be a key technology to maintain a certain lubricating effect of the transmission components under the environment of heavy load and temperature rise. Through the analysis of friction coefficient and electrical contact resistance, the greases are used to test the lubricating effect of the transmission elements under the heavy load condition. The results will be helpful for the industry to use heavy load greases as a reference.

Effects of Surface Roughness on Sliding Friction in Lubricated-Point Contacts: Experimental and Numerical Studies

2007 ◽  
Vol 129 (4) ◽  
pp. 809-817 ◽  
Author(s):  
Shun Wang ◽  
Yuan-zhong Hu ◽  
Wen-zhong Wang ◽  
Hui Wang
Keyword(s):  
Surface Roughness ◽  
Sliding Friction ◽  
Operating Conditions ◽  
Point Contacts ◽  
Machining Processes ◽  
Friction Behavior ◽  
Type Curves ◽  
Lubrication Regimes ◽  
Wide Range ◽  
Transverse Roughness

The objective of the present work is to investigate experimentally and numerically the influences of surface roughness, produced by typical machining processes, on friction performances in lubricated-point contacts. Prior to the full experimental investigation, a series of tests had been conducted to examine the experimental errors, resulting from repeated tests on the same specimen but at different tracks, with different amounts of lubricant supply, or after the sample reinstallation. Then, the effects of amplitude and texture of surface roughness on friction behavior are investigated in rotational and reciprocal-mode tests, respectively. The measured friction, averaged over the repeated tests and plotted as a function of sliding speed, shows Stribeck-type curves, which manifest the transition from full-film, mixed, to boundary lubrication. Results show that the roughness amplitude imposes a strong influence on the magnificence of friction and the route of lubrication transition. It is also observed that transverse roughness would give rise to a smaller friction coefficient than the longitudinal one under the same operating conditions. Moreover, the deterministic numerical solution of mixed lubrication has been extended to evaluate friction between rough surfaces over a wide range of lubrication regimes. The numerical simulation results are compared and agree very well with experiments.

Effects of Vanadium Oxide Nanoparticles on Friction and Wear Reduction

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Wei Dai ◽  
Kyungjun Lee ◽  
Alexander M. Sinyukov ◽  
Hong Liang
Keyword(s):  
Friction And Wear ◽  
Hydrodynamic Lubrication ◽  
Tribological Performance ◽  
Friction Reduction ◽  
Tribochemical Reaction ◽  
Base Oil ◽  
Lubrication Regimes ◽  
Wear Reduction ◽  
Light Mineral ◽  
Effective Additive

In this research, rheological and tribological performance of additive V2O5 nanoparticles in a light mineral oil has been investigated. For rheological performance, the addition of 0.2 wt. % V2O5 could reduce the viscosity of the base oil for 6%. Considering the overall friction reduction in boundary, mixed, and hydrodynamic lubrication regimes, that with 0.1 wt. % V2O5 exhibited the best effect. Friction coefficient of base oil could be reduced by 33%. In terms of wear, the addition of 0.2 wt. % V2O5 showed the lowest wear rate, which is 44% reduction compared to base oil. Through Raman spectrum and energy dispersive spectroscopy (EDS) analysis, it was found that V2O5 involved tribochemical reaction during rubbing. Vanadium intermetallic alloy (V–Fe–Cr) was found to enhance the antiwear performance. This research revealed that V2O5 nanoparticles could be an effective additive to improve tribological performance.

scholarly journals Tribological performance of organic molybdenum in the presence of organic friction modifier

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252203
Author(s):  
Weiwei Wang ◽  
Zhuangzhuang Liu ◽  
Qimin Song ◽  
Xindi Zhang ◽  
Shengkai Jiao ◽  
...  
Keyword(s):  
High Temperature ◽  
Friction Coefficient ◽  
Low Temperature ◽  
Synergistic Effect ◽  
Tribological Performance ◽  
Friction Reduction ◽  
Ring Test ◽  
Friction Modifiers ◽  
Friction Modifier ◽  
Glycerol Monooleate

The tribological performance of organic molybdenum in the present of organic friction modifier was investigated in this study. Three types of organic friction modifiers were selected, which are Glycerol monooleate, Pentaerythritol and N,N-Dimethylhexadecylamine. The organic molybdenum are MoDTC, MoDDP and molybdenum amide. Friction coefficient and wear were studied in block-on-ring test rig with steel test specimens. Experimental results indicate the Pentaerythritol shows synergistic effect with MoDTC in wide range temperature, while increased the friction coefficient of molybdenum amide in high temperature. N,N-Dimethylhexadecylamine shows synergistic effect with molybdenum amide, while hindered the friction reduction performance of MoDTC in low temperature. The presence of Glycerol monooleate reduced friction coefficient of MoDTC in low temperature, while increased the friction coefficient of molybdenum amide in most situations. All the tested organic friction modifiers improved the friction reduction performance of MoDDP. Most of the tested organic friction modifiers reduced the wear of organic molybdenum. The PT shows the best anti-wear performance with MoDTC. The tribo-chemical products in test specimens lubricated with different lubricant formulas indicate that the presences of Pentaerythritol promotes the production of MoS2 in MoDTC. N,N-Dimethylhexadecylamine promotes the production of MoS2 in molybdenum amide. The side products of MoO1.6S1.6 and Cr/MoS2 of MoDDP in high temperature lead to high friction coefficient.

THE EFFECT OF SURFACE ROUGHNESS AND MATERIAL HARDNESS ON THE TRIBOLOGICAL PERFORMANCE OF THE SLIDING PAIR WC-42CrMo4 UNDER STARVED LUBRICATION

Tribologia ◽  
2019 ◽  
Vol 286 (4) ◽  
pp. 5-13
Author(s):  
Lidia GAŁDA ◽  
Jan SMYKLA
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Ceramic Materials ◽  
Industrial Applications ◽  
Tribological Performance ◽  
Operating Conditions ◽  
Quadratic Functions ◽  
Material Hardness ◽  
Machine Elements ◽  
Effect Of Surface

Ceramic materials are more and more popular in industrial applications. Machine elements made of ceramic materials are characterized by long durability, especially those elements that work in hard operating conditions. In this paper, the results of tribological examinations of WC-42CrMo4 sliding pair are presented. Tribological tests were realized with the T-11 stand with the ball-on-disc sliding pair. For lubrication, the machine mineral oil L-AN 46 was used. The analysis showed that surface roughness significantly affected the tribological performance of tested sliding pairs. Steel samples were characterized with various hardnesses in the range of 22-42 HRC and this feature also effected on friction coefficient. Statistical analyses of the achieved results were made using the 3-level PS/DC 32 design. According to the statistical analysis, the quadratic functions describing the dependence for friction coefficient on surface roughness and material hardness were obtained. The most unfavourable surface roughness was after the grinding process, but the best was those after the lapping process which allows the smallest friction coefficient.

Electrical Contact Resistance Approach to Tribological Properties of Artificial Joints

2008 ◽  
Vol 594 ◽  
pp. 383-388
Author(s):  
Yuh Ping Chang ◽  
Ruei Hong Wang ◽  
Yu Yang Hung ◽  
Huann Ming Chou ◽  
Jin Chi Wang
Keyword(s):  
Friction Coefficient ◽  
Contact Resistance ◽  
Tio2 Film ◽  
Tribological Properties ◽  
Electrical Contact ◽  
Dynamic Monitoring ◽  
The Novel ◽  
Semiconductor Films ◽  
Electrical Contact Resistance ◽  
Novel Method

The tribo-electrification mechanisms had been successfully applied to dynamic monitor the tribological properties between the metal films by our laboratory members. Moreover, the novel method of using continuous tribo-electrification variations for monitoring showed more sensitive and discriminative than that by the continuous friction coefficient variations as usual. However, the above method is only suitable for the conducted material pairs. This study is based on the above views to further develop another novel method for dynamic monitoring the tribological properties between the semiconductor films in the friction process. The experiment was conducted by the self-developed friction tester and its measure system. The continuous variations of electrical contact resistance and friction coefficient were measured for monitoring the timings of film rupture between the semiconductor films. Moreover, the wear loss was measured by an accuracy balance and the SEM was used to observe the structures of material transfer. Therefore, the wear mechanisms of Ti sliding against Ti with TiO2-film under different normal loads can be investigated. According to the experimental results of this study, the novel method of using electrical contact resistance variations does show great potentialities for dynamic monitoring the tribological properties of the TiO2-film.

Friction Reduction in Lubricated Rough Contacts: Numerical and Experimental Studies

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Zhiqiang Liu ◽  
Arup Gangopadhyay
Keyword(s):  
Friction Coefficient ◽  
Ambient Pressure ◽  
Classical Model ◽  
Experimental Studies ◽  
Elastohydrodynamic Lubrication ◽  
Contact Problems ◽  
Friction Reduction ◽  
Asperity Contact ◽  
Oil Viscosity ◽  
Lubrication Regimes

Combining the contact model of elastic-layered solid with the concept of asperity contact in elastohydrodynamic lubrication (EHL), a mixed-lubrication model is presented to predict friction coefficient over rough surfaces with/without an elastic-layered medium under entire lubrication regimes. Solution of contact problems for elastic-layered solids is presented based upon the classical model of Greenwood and Williamson (GW) in conjunction with Chen and Engel's analysis. The effects of the Young's modulus ratio of the layer to substrate and the thickness of the layer on the elastic real area of contact and contact load for a fixed dimensionless separation are studied using the proposed method, which is used for the asperities having contact with an elastic coating. Coefficient of friction with elastic-layered solids in boundary lubrication is calculated in terms of Rabinowicz's findings and elastic-layered solutions of Gupta and Walowit. The effect of rough contacts with an elastic layer on friction coefficient in lubrication regimes has been analyzed. Variations in plasticity index ψ significantly affect friction coefficients in boundary and mixed lubrications. For a large value of ψ, the degree of plastic contact exhibits a stronger dependence of the mean separation or film thickness than the roughness, and for a small value of ψ, the opposite result is true. The effect of governing parameters, such as inlet oil viscosity at ambient pressure, pressure–viscosity coefficient, combined surface roughness, and El/E2 on friction coefficient, has been investigated. Simulations are shown to be in good agreement with the experimental friction data.

Parametric Study of the Behavior of a Mechanical Face Seal Operating in Mixed and TEHD Lubrication Regimes

2012 ◽  
Author(s):  
André Parfait Nyemeck ◽  
Noël Brunetière ◽  
Bernard Tournerie
Keyword(s):  
Heat Transfer ◽  
Friction Coefficient ◽  
Mixed Lubrication ◽  
Operating Conditions ◽  
Fluid Viscosity ◽  
Face Seal ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
Mechanical Face Seal ◽  
Mixed Lubrication Regime

In this paper, the behavior of a mechanical face seal is analyzed for different operating conditions and designs. For that, a theoretical model including a multiscale approach of the mixed lubrication regime, heat transfer and deformation of the seal rings is used. It has been possible to clearly identify the three different lubrication regimes of a mechanical seal: the mixed lubrication where the friction coefficient decreases, the rough hydrodynamic regime corresponding to an increasing friction and then the thermo-elasto-hydrodynamic (TEHD) regime for which the coefficient of friction is approximately constant. In this work, the influence of the fluid pressure, the seal roughness height, the balance ratio, the rings materials, the dry friction coefficient and viscosity are respectively examined. Generally speaking, the variation of these parameters affects the location of the optimum value of the friction coefficient in the mixed lubrication regime. In the TEHD regime, the temperature is mainly influenced by the materials and the fluid viscosity, which control the amplitude of deformation and heat transfer. A dimensionless parametric analysis has been carried out in order to perform an overall discussion of the results. It is shown that the mixed and rough hydrodynamic lubrication regimes are controlled by the modified duty parameter, while the TEHD regime is controlled by the sealing parameter.

Optimising lubricated friction coefficient by surface texturing

2013 ◽  
Vol 227 (11) ◽  
pp. 2610-2619 ◽  
Author(s):  
E de la Guerra Ochoa ◽  
J Echávarri Otero ◽  
E Chacón Tanarro ◽  
P Lafont Morgado ◽  
A Díaz Lantada ◽  
...  
Keyword(s):  
Experimental Data ◽  
Friction Coefficient ◽  
Chemical Etching ◽  
Surface Texturing ◽  
Point Contact ◽  
High Load ◽  
Operating Conditions ◽  
Textured Surface ◽  
Lubrication Regimes ◽  
Texture Size

Surface texturing has proved to be a very useful tool for expanding the behaviour under hydrodynamic and elastohydrodynamic regimes instead of mixed or boundary lubrication regimes, and therefore for reducing the friction coefficient under high-load low-speed conditions. This article presents the texturing of different copper test-samples using photolithography and chemical etching to measure the friction coefficient using a point contact machine. The effects of texture size, texturing density, the initial roughness of the samples and the operating conditions have all been studied. Some combinations of texturing density and texture size achieve up to 30% reduction in the friction coefficient. Taking into account experimental data, artificial neural networks are used as a tool for both predicting and optimising the friction coefficient on the textured surface for any given operating condition.

Piston dynamics, lubrication and tribological performance evaluation: A review

2018 ◽  
Vol 21 (5) ◽  
pp. 725-741 ◽  
Author(s):  
Cristiana Delprete ◽  
Abbas Razavykia
Keyword(s):  
Power Loss ◽  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Tribological Performance ◽  
Operating Conditions ◽  
Friction Reduction ◽  
Design Parameters ◽  
Combustion Engines ◽  
Piston Skirt ◽  
Secondary Motion

Mechanical power loss of lubricated and bearing surfaces serves as an attractive domain for study and research in the field of internal combustion engines. Friction reduction at lubricated and bearing surface is one of the most cost-effective ways to reduce gas emission and improve internal combustion engines’ efficiency. This thus motivates automotive industries and researchers to investigate tribological performance of internal combustion engines. Piston secondary motion has prime importance in internal combustion engines and occurs due to unbalanced forces and moments in a plane normal to the wrist pin axis. Consequently, piston executes small translations and rotations within the defined clearance during the piston reciprocating motion. Mechanical friction power loss and lubrication at piston skirt/liner and radiated engine noise are dramatically affected by piston secondary dynamics. The lubrication mechanism, piston secondary motion and tribological performance are affected by piston design parameters (piston/liner clearance, wrist pin offset, skirt profile, etc.), lubricant rheology, oil transport mechanism and operating conditions. Therefore, this review is devoted to summarize the synthesis of main technical aspects, research efforts, conclusions and challenges that must be highlighted regarding piston skirt/liner lubrication and piston dynamics and slap.

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