A Novel Surface Texture Shape for Directional Friction Control

An experimental study is presented to evaluate the influence of anisotropically shaped textures on the behaviour of sliding
friction and sensitivity to sliding direction. The plate samples were textured with triangular sloped dimples using an ultrafast
laser surface texturing technique. Reciprocating cylinder-on-plate tests were conducted with steel sliding pairs using mineral
base oil as a lubricant to compare the tribological performance of reference non-textured specimen and dimpled samples.
The dimples were designed with varying converging angles in the transverse y–z plane and top-view x–y plane. In this study,
no dimple was fully covered in the contact area since the dimples size is much larger than the Hertzian line contact width.
Stribeck style dynamic friction curves across boundary, mixed and hydrodynamic lubrication regimes were used to determine
the benefit or antagonism of texturing. Observation of the directional friction effect of the anisotropic textures indicated
that the converging shapes are beneficial for friction reduction, and the dimpled specimens have a lower friction coefficient
particular under prevailing boundary lubrication conditions. ... mehrIt was also found that the real contact length variation rate is a
major factor controlling the local friction response. The sloped bottoms of the textures produce effective converging wedge
action to generate hydrodynamic pressure and contribute to the overall directional friction effects.