407 Effect of Surface Roughness Profile on the Friction Coefficient of Rolling-Sliding Contact Surface under Mixed Lubrication

2013 ◽  
Vol 2013.66 (0) ◽  
pp. 125-126
Author(s):  
Nobumitsu TOYOTA ◽  
Susumu MATSUMOTO
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Contact Surface ◽  
Mixed Lubrication ◽  
Sliding Contact ◽  
Roughness Profile ◽  
Effect Of Surface

The comprehensive effect of surface texture and roughness under hydrodynamic and mixed lubrication conditions

2017 ◽  
Vol 231 (10) ◽  
pp. 1307-1319 ◽  
Author(s):  
Chenbo Ma ◽  
Yanjun Duan ◽  
Bo Yu ◽  
Jianjun Sun ◽  
Qiaoan Tu
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Hydrodynamic Lubrication ◽  
Diameter Ratio ◽  
Mixed Lubrication ◽  
Textured Surface ◽  
Texture Parameters ◽  
Lubrication Condition ◽  
Lubrication Conditions ◽  
Effect Of Surface

A theoretical study is carried out to investigate the comprehensive effect of the machined roughness and fabricated textures, by solving the average Reynolds equation coupled with a mass-conservative cavitation algorithm and taking into account asperity contact. We analyzed the influence of surface roughness, which is represented by the combined root-mean-square roughness σ and surface pattern parameter γ on the optimum texture parameters including the dimple depth-over-diameter ratio and area density under hydrodynamic and mixed lubrication conditions. The results show that the effect of surface roughness on load-carrying capacity can be ignored under hydrodynamic lubrication condition. Furthermore, the optimum texture parameters under hydrodynamic lubrication condition and the optimum dimple depth-over-diameter ratio under mixed lubrication condition are determined at minimized friction coefficient, which can be taken as the same for smooth-textured surface and rough-textured surface. The corresponding minimum friction coefficient increases with increasing σ and γ, and decreasing dimple area density under mixed lubrication condition.

Measurement and Evaluation of the Static Friction Coefficient Between Fixed Coupling Surfaces Under Face Contact and High Contact Pressure

2020 ◽  
Author(s):  
Fumihiko Inagaki ◽  
Noboru Morita ◽  
Hirofumi Hidai ◽  
Souta Matsusaka ◽  
Tatsuo Ohmori ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Contact Pressure ◽  
Contact Surface ◽  
Contact Stiffness ◽  
Tangential Force ◽  
Sampling Rate ◽  
Static Friction ◽  
Measurement Device ◽  
Static Friction Coefficient

Abstract At the joints of the mechanical systems, it is well known that the parameters such as contact stiffness, static friction coefficient, kinetic friction coefficient and attenuation coefficient affect static, kinetic, thermal and motion characteristic of them strongly. In these parameters, the static friction coefficient reigns the character of maximum fixing resistance. However, there’s difficulties for measure the precise static friction coefficient on the coupling surfaces due to tiny contact surface, unstable loading method and moment force acts on the contact surface of the former device. Therefore, we developed novel measurement device and evaluated influence of the surface parameters given to static friction coefficient. Through the validity evaluation, it was confirmed that the new measurement device enables face contact and uniform surface pressure. In addition, there’s no moment force by optimizing the loading position of the tangential force. Furthermore, validity of the static friction coefficient was checked and verified that frequency of the sampling rate is fine enough. Finally, we proceeded to applied test with this new measurement device for evaluate the influence of the surface roughness and grinding direction given to static friction coefficient. A pair of die steels and cemented carbides was selected for specimen and static friction coefficient was measured under 60 MPa of contact pressure. Regarding influence of surface roughness, the result showed tendency that rougher surface generates lower value of the static friction coefficient. Now for grinding direction, combination of the specimen ground in orthogonal direction against tangential force showed maximum value and the specimen ground in parallel direction against tangential force showed minimum.

A Friction Model for Cold Strip Rolling With Two-Wavelength Surface Roughness in the “Mixed” Lubrication Regime

2003 ◽  
Vol 125 (3) ◽  
pp. 670-677 ◽  
Author(s):  
H. R. Le ◽  
M. P. F. Sutcliffe
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Rolling Direction ◽  
Hydrodynamic Pressure ◽  
Friction Model ◽  
Mixed Lubrication ◽  
Strip Rolling ◽  
Lubrication Regime ◽  
Mixed Lubrication Regime ◽  
Cold Metal

A two-dimensional friction model has been developed for cold metal rolling in the “mixed” lubrication regime. Roughness is modelled using superimposed short and long wavelength asperities with a lay orientated along the rolling direction. The hydrodynamic pressure in the lubricant is solved using Reynolds’ equation, coupled with the crushing process of the two-wavelength roughness. This allows for the solution of film thickness and contact area ratio and hence friction coefficient through the roll-bite. The model extends the authors’ earlier model [15] by allowing for a variation in hydrodynamic pressure across the width of the contact. Predictions for both the surface roughness and the friction coefficient are in reasonable agreement with published measurements.

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