Surface Texturing Effect, Characterization and Optimization for Boundary and Mixed Lubrication

2011 ◽  
Author(s):  
B. Podgornik ◽  
M. Sedlacˇek
Keyword(s):  
Surface Topography ◽  
Research Work ◽  
Surface Texturing ◽  
Considerable Change ◽  
Mixed Lubrication ◽  
Design Parameters ◽  
Textured Surfaces ◽  
Tribological Behaviour ◽  
Cavity Depth ◽  
Lubricated Contacts

Under boundary and mixed lubrication surface roughness and topography have significant influence on the tribological behaviour of contact surfaces, where even a small change in surface topography can lead to a considerable change in tribological behaviour. In recent years an effort for better controlling friction and wear has been focused also on the surface topography modification, especially on surface texturing. The aim of the present research work was to investigate the possibility of using roughness parameters kurtosis and skewness as design parameters for optimizing texturing pattern in boundary and mixed lubricated contacts. Results of the investigation performed on groove and dimple textured surfaces under low load low sliding speed conditions confirm correlation between kurtosis and skewness parameters and coefficient of friction. For textured surfaces increase in kurtosis and more negative skewness, obtained by reducing cavity size, increasing cavity depth and decreasing texturing density were found to yield lower friction. Furthermore, kurtosis and skewness were recognized as suitable parameters for textured surfaces optimization. Through virtual texturing effect of different texturing parameters on kurtosis and skewness parameters can be identified and then optimized to result in reduced friction under boundary and mixed lubrication.

Performance, Characterization and Design of Textured Surfaces

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
B. Podgornik ◽  
M. Sedlacek
Keyword(s):  
Friction And Wear ◽  
Research Work ◽  
Surface Texturing ◽  
Design Parameters ◽  
Textured Surfaces ◽  
Cavity Depth ◽  
Analytical Work ◽  
Low Load ◽  
Negative Skewness ◽  
The Coefficient Of Friction

In recent years the efforts to better control friction and wear have focused on surface-topography modification through surface texturing. Although a lot of effort, including experimental and analytical work, has been put into finding the optimal texturing parameters and design rules for reduced friction, optimization is still too often limited and based on a trial-and-error approach. Therefore, the aim of the present research work was to investigate the possibility of using kurtosis and skewness as the design parameters for selecting the optimal texturing pattern for contact surfaces operating under lubricated conditions. The results of this investigation performed on groove- and dimple-textured surfaces under low-load, low-sliding speed conditions confirmed the correlation between the kurtosis and skewness parameters and the coefficient of friction. For textured surfaces an increase in the kurtosis and a more negative skewness, obtained by reducing the cavity size, increasing the cavity depth and decreasing the texturing density, were found to yield a lower friction. Furthermore, kurtosis and skewness were recognized as suitable parameters for the optimization of textured surfaces.

scholarly journals The Influence of Surface Texturing on the Frictional Behaviour of Parallel Sliding Lubricated Surfaces under Conditions of Mixed Lubrication

Lubricants ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 91 ◽  
Author(s):  
Dariush Bijani ◽  
Elena L. Deladi ◽  
Aydar Akchurin ◽  
Matthijn B. de Rooij ◽  
Dirk J. Schipper
Keyword(s):  
Coefficient Of Friction ◽  
Film Formation ◽  
Surface Texturing ◽  
Industrial Applications ◽  
Mixed Lubrication ◽  
Tribological Behaviour ◽  
Surface Geometry ◽  
Lubricated Contacts ◽  
The Coefficient Of Friction ◽  
Frictional Behaviour

In many industrial applications, a modification of the surface geometry can enhance the tribological behaviour of lubricated sliding contacts. In this paper, the effect of surface texturing on the coefficient of friction in parallel sliding lubricated surfaces is investigated. It is shown that surface texturing can improve film formation and, as a result, the load-carrying capacity as well as a reduction in the coefficient of friction. With the numerical model developed, and by considering cavitation, the effects of shape, depth, size, and the textured area fraction on the frictional behaviour of parallel sliding lubricated contacts under conditions of mixed lubrication is studied. In this article it is shown that the surface texturing can have a beneficial effect, in order to decrease friction.

scholarly journals Fast laser surface texturing of spherical samples to improve the frictional performance of elasto-hydrodynamic lubricated contacts

Friction ◽  
2021 ◽  
Author(s):  
G. Boidi ◽  
P. G. Grützmacher ◽  
A. Kadiric ◽  
F. J. Profito ◽  
I. F. Machado ◽  
...  
Keyword(s):  
Surface Texturing ◽  
Hydrodynamic Pressure ◽  
Friction Reduction ◽  
Laser Surface Texturing ◽  
Textured Surfaces ◽  
Engineering Applications ◽  
Lubricated Contacts ◽  
Fluid Uptake ◽  
Direct Laser ◽  
Frictional Performance

AbstractTextured surfaces offer the potential to promote friction and wear reduction by increasing the hydrodynamic pressure, fluid uptake, or acting as oil or debris reservoirs. However, texturing techniques often require additional manufacturing steps and costs, thus frequently being not economically feasible for real engineering applications. This experimental study aims at applying a fast laser texturing technique on curved surfaces for obtaining superior tribological performances. A femtosecond pulsed laser (Ti:Sapphire) and direct laser interference patterning (with a solid-state Nd:YAG laser) were used for manufacturing dimple and groove patterns on curved steel surfaces (ball samples). Tribological tests were carried out under elasto-hydrodynamic lubricated contact conditions varying slide-roll ratio using a ball-on-disk configuration. Furthermore, a specific interferometry technique for rough surfaces was used to measure the film thickness of smooth and textured surfaces. Smooth steel samples were used to obtain data for the reference surface. The results showed that dimples promoted friction reduction (up to 20%) compared to the reference smooth specimens, whereas grooves generally caused less beneficial or detrimental effects. In addition, dimples promoted the formation of full film lubrication conditions at lower speeds. This study demonstrates how fast texturing techniques could potentially be used for improving the tribological performance of bearings as well as other mechanical components utilised in several engineering applications.

Modeling of Surface Topography for Reduced Friction

2008 ◽  
Author(s):  
Marko Sedlacˇek ◽  
Bojan Podgornik ◽  
Jozˇe Vizˇintin
Keyword(s):  
Surface Roughness ◽  
Surface Topography ◽  
Surface Texturing ◽  
Test Results ◽  
Textured Surfaces ◽  
Roughness Parameters ◽  
Contact Conditions ◽  
Surface Roughness Parameters ◽  
Pin On Disc ◽  
Texture Size

The aim of the present research was to investigate surface topography in terms of different surface roughness parameters and to correlate surface topography change to friction of contact surfaces. For this purpose, different 100Cr6 plate samples with different surface topography were prepared. Using different grades and combinations of grinding and polishing samples with similar Ra values, but different Rku and Rsk values were obtained. To evaluate influence of roughness parameters on friction and wear, dry and lubricated pin-on-disc tests were carried out under different contact conditions. Test results indicate that high Rku and negative Rsk values lead to decrease in friction. To investigate the effect of surface texturing on surface roughness parameters, real roughness profiles were virtually altered to achieve virtually textured surfaces. Using NIST SMATS softgauge for calculation of surface roughness parameters, virtually altered roughness profiles were investigated in terms of texture size, shape and spacing, and their influence on surface roughness parameters, especially on skewness and kurtosis. Lower diameter, higher spacing and wedge-shaped dimples reflect in higher Rku and more negative Rsk parameters.

scholarly journals The effect of surface texturing in the sliding surface on tribological characteristics of alloy steel under wet condition

2021 ◽  
Vol 15 (57) ◽  
pp. 1-13
Author(s):  
Hiralal S. Patil ◽  
D. C. Patel
Keyword(s):  
Alloy Steel ◽  
Surface Texturing ◽  
Mixed Lubrication ◽  
Tribological Characteristics ◽  
Wear Behaviour ◽  
Wear Loss ◽  
Textured Surfaces ◽  
Micro Drilling ◽  
Wet Condition ◽  
En 31

Surface texturing plays a significant role on the tribological performance of contact surfaces. The tribological characteristics are mostly dependent upon the different pattern and methods of surface texturing. This research works investigates lubricated wear behaviour on circular dimples textured EN-31 alloy steel materials using DUCOM linear reciprocating tribometer. The surface dimples are fabricated by micro-EDM and micro-drilling CNC methods. Initially plane surfaces are tested under different lubricants ISO-68 and ISO-220 oil on a couple of EN31 plates with EN8 steel pin. At loading conditions the results clearly shows that the ISO 68 oil gives better performance than ISO-220 oil in terms of frictional force and COF. The operation during test under ISO-220 oil observed is very noisy and wear rate is also more. Then after experiments under different load conditions on textured surfaces were investigated using optimized ISO-68 oil. An experimental results on m-EDM provides superior frictional characteristics with respect to m-CNC. Surface texturing may act as wear debris trapper, lubricant reservoirs, hydrodynamic lift, and retarding the lubricant molecules flow in a particular path where potential exists. Here micro-dimples EDM surface textures can enhance mixed lubrication and in mixed lubrication the friction is least and this may leads to decrement of wear loss.

scholarly journals The Influence of Surface Texturing on the Frictional Behaviour in Starved Lubricated Parallel Sliding Contacts

Lubricants ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 68 ◽  
Author(s):  
Bijani ◽  
Deladi ◽  
Rooij ◽  
Schipper
Keyword(s):  
Coefficient Of Friction ◽  
Surface Texturing ◽  
Geometrical Parameters ◽  
Textured Surfaces ◽  
Tribological Behaviour ◽  
Sliding Contacts ◽  
Cavitation Effect ◽  
The Coefficient Of Friction ◽  
Starved Lubrication ◽  
Frictional Behaviour

Starvation occurs when the lubricated contact uses up the lubricant supply, and there is not enough lubricant in the contact to support the separation between solid surfaces. On the other hand, the use of textures on surfaces in lubricated contacts can result in a higher film thickness. In addition, a modification of the surface’s geometrical parameters can benefit the tribological behaviour of the contacts. In this article, for parallel sliding surfaces in starved lubricated conditions, the effect of surface texturing upon the coefficient of friction is investigated. It is shown that surface texturing may improve film formation under the conditions of starvation, and as a result, the frictional behaviour of the parallel sliding contact. Furthermore, the effect of starved lubrication on textured surfaces with different patterns in the presence of a cavitation effect, and its influence on frictional behaviour, is investigated. It is shown that surface texturing can reduce the coefficient of friction, and that under certain conditions, the texturing parameter could have an influence on the frictional behaviour of parallel sliding contacts in the starved lubrication regime.

Effect of Surface Topography on Mixed Lubrication Film Under Transient Conditions

2009 ◽  
Author(s):  
Ivan Krupka ◽  
Martin Hartl ◽  
Petr Svoboda
Keyword(s):  
Surface Topography ◽  
Film Formation ◽  
Surface Damage ◽  
Mixed Lubrication ◽  
Real Surface ◽  
Transient Conditions ◽  
Lubrication Film ◽  
Lubricated Contacts ◽  
Start Up ◽  
Ball Surface

Surface topography plays an important role in the efficiency of lubricated contacts formed between highly loaded machine parts. Gears, rolling bearings, cam and followers etc. subjected to high loads and/or slow speeds are operated under mixed lubrication when lubrication film is not able to completely separate rubbing surfaces. Such an effect becomes even more serious under transient conditions that bring the risk of the surface damage because of asperities interactions. This paper focuses on the effects of both artificially produced and real roughness features on mixed lubrication film formation during start up motion of non-conformal contacts operated under rolling/sliding conditions. The observation of the effects of surface dents artificially produced on the ball surface helped to understand better the behavior of real surface topography. It was found that the presence of shallow surface features can help to separate mixed lubricated rubbing surfaces more efficiently than it could be suggested from the results obtained with smooth surfaces.

The Influence of Surface Patterning on the Thermal Properties of Textured Thrust Bearings

2017 ◽  
Author(s):  
Gen Fu ◽  
Alexandrina Untaroiu
Keyword(s):  
Surrogate Model ◽  
Load Capacity ◽  
Computing Time ◽  
Friction Torque ◽  
Fluid Film ◽  
Design Parameters ◽  
Textured Surface ◽  
Textured Surfaces ◽  
Thrust Bearings ◽  
Lubricated Contacts

Contact performance can be enhanced by using textured surfaces. These are also found to have influences on lubricated contacts. The effects of textured surface on lubricated contacts has been widely investigated over the past twenty years. The property of lubricated contacts has been found to play an important role on the performance of fluid film bearings. According to the previous study, the introduction of dimples on the inner surfaces of parallel thrust bearings can improve the load capacity and reduce the friction. Since the friction loss is mostly converted to thermal energy and then increase the temperature, textured surface is expected to have a positive effect on the thermal property of the thrust bearings. A procedure to find the optimal partially texture geometry, which minimize the temperature inside the bearing film, is presented in this study. A parallel sector-pad thrust bearing is simulated by a 3D computational fluid dynamics model. The stationary surface of the bearing is textured with dimples while the rotor surface is flat. The results of the baseline model have been validated by the experimental data from the literature. The temperature and pressure distribution on the bearing pad are presented. In this study, two types of dimples, including rectangular and elliptical, are compared together. A parametric study is conducted to investigate the influence of the texture geometries. In this study, the length of the major axis (width), the length of the minor axis (length), dimple depth, circumferential space between two dimples, radial space between two dimples, radial extend and circumferential extend are selected as design parameters. A surrogate model is used to reduce the computing time of CFD analysis. Based on the surrogate model, a multi-objective optimization scheme is used to navigate the design space and find the optimal texture structure that provides a lower maximal temperature inside the fluid film, higher load capacity, and lower friction torque. The optimal radial extent of the texture is around 80% of the pad radial length for both cases. The optimal length of the elliptical dimples in the circumferential direction is about 30% larger than the value of the rectangular dimples. In the final optimal design, the maximal temperature reduces 1.1% and 1.3% for rectangular and elliptical dimples while the load capacities are maintained at the same level.

The Influence of Surface Patterning on the Thermal Properties of Textured Thrust Bearings

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Gen Fu ◽  
Alexandrina Untaroiu
Keyword(s):  
Surrogate Model ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Three Dimensional ◽  
Major Axis ◽  
Friction Torque ◽  
Design Parameters ◽  
Textured Surfaces ◽  
Lubricated Contacts ◽  
Radial Extent

Contact performance can be enhanced by using textured surfaces. These are also found to have influences on lubricated contacts. A procedure to find the optimal partially textured thrust bearing configuration is presented in this study. A parallel sector-pad thrust bearing is simulated by a three-dimensional (3D) computational fluid dynamics (CFD) model. The stationary surface of the bearing is textured with dimples, while the rotor surface is flat. The results of the baseline model are validated by experimental data. In this study, we compare rectangular and elliptical dimples by investigating design parameters, such as major the length of the major axis (width), the length of the minor axis (length), dimple depth, circumferential space between two dimples, radial space between two dimples, radial extent, circumferential extent are selected as design parameters. A parametric study is conducted to investigate the influence of the texture geometries and a surrogate model is created. Based on the surrogate model, a multi-objective optimization scheme is used to navigate the design space and find the optimal texture structure that provides a lower maximal temperature inside the fluid film, higher load capacity, and lower friction torque. The results show that the optimal radial extent of the texture is around 80% of the pad radial length for both cases. The optimal length of the elliptical dimples in the circumferential direction is about 30% larger than the value of the rectangular dimples. In the final optimal design, the maximal temperature reduces 1.1% and 1.3% for rectangular and elliptical dimples while the load capacities are maintained at the same level.

scholarly journals Effect of Low Depth Surface Texturing on Friction Reduction in Lubricated Sliding Contact

Lubricants ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 62 ◽  
Author(s):  
Haytam Kasem ◽  
Ori Stav ◽  
Philipp Grützmacher ◽  
Carsten Gachot
Keyword(s):  
Research Work ◽  
Surface Texturing ◽  
Friction Reduction ◽  
Laser Surface Texturing ◽  
Surface Pattern ◽  
Textured Surfaces ◽  
Laser Interference ◽  
Wear Properties ◽  
Direct Laser ◽  
Direct Laser Interference Patterning

Laser surface texturing is an interesting possibility to tailor materials’ surfaces and thus to improve the friction and wear properties if proper texture feature sizes are selected. In this research work, stainless steel surfaces were laser textured by two different laser techniques, i.e., the direct laser interference patterning by using a nanosecond pulsed Nd:YAG laser and additionally by an ultrashort pulsed femtosecond Ti:Sa. The as-textured surfaces were then studied regarding their frictional response in a specially designed linear reciprocating test rig under lubricated conditions with a fully formulated 15W40 oil. Results show that dimples with smaller diameter lead to a significant reduction in the coefficient of friction compared to the dimples with a larger diameter and surfaces with a grid-like surface pattern produced by direct laser interference patterning.

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