Influence of a Surface Bump or Groove on the Lubricating Performance and Dimple Phenomena in Simple Sliding Point EHL Contacts

Abstract

The influence of a transversely or longitudinally oriented surface bump or groove on the lubricating performance and dimple phenomena in the simple sliding point contact composed of a steel ball and a glass disk has been investigated theoretically with numerical solution of the thermal elastohydrodynamic lubrication (EHL) and experimentally with optical interferometry technique. Good agreement has been obtained between the theoretical and experimental results. It has also been discovered that the surface bump or groove is dangerously harmful to the lubricating performance and has a significant influence on the dimple phenomena.

Reducing the friction of lubricated nonconformal point contacts by transverse shallow micro-grooves

“…However, the amount of the side leakage decreases with reducing the size (width and depth of micro-groove) and increasing the overall film thickness. Yang et al 32 proved numerically the results of Kaneta. Nakano et al 33 stated that groove patterns have higher fiction coefficients than the flat surfaces because groove patterns have not enough ability to keep the hydrodynamic pressure.…”

“…They attributed that effect to the channeling of the lubricant away from the contact. Although the negative effects observed numerically and experimentally with micro-grooves in the literature, 13,[30][31][32][33] the authors introduce in this paper an innovative approach to obtain benefits from transverse shallow micro-grooves in EHL contacts. The approach depends on eliminating the side leakage along grooves by reducing the length of groove to be less than the diameter of the Hertzian contact.…”

Action of a femtosecond laser generated micro-cavity passing through a circular EHL contact

“…Over the last 3 decades, the fundamental understanding of the effects generated by such sub-contact scale features on the behaviour of elasto-hydrodynamically lubricated (EHL) contacts have become a research subject of major importance, commonly named -EHL. Unprecedented improvements both in computational techniques [1], and in film thickness measurement methods, allowed important numerical and experimental contributions [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In the case of hydrodynamic and mixed lubrication, it has been demonstrated that micro-texturing one of the contacting surfaces with optimized micro-dimples could reduce friction and wear [18,19].…”

Boundary Lubricated Friction Experiments With Coarse Surface Texture

“…Reported benefits of texture can be very substantial: decrease in operating temperature by tens of degrees [5], decrease in friction by 30% [1], moving the Stribeck curve to the left [4], increase in seizure or breakdown load by 2-10 times [5,6], etc. However, in other cases only negative effects have been reported [7,8].…”