A Study of Micro-Dimpled Groove Texture in Friction Reduction

Friction control is a vital green technology for reaching sustainable development goals, and surface texturing is effective and efficient at reducing friction. In this study, a novel preparation scheme involving dimpled groove texture is proposed. A pulsed laser marking system is used to make the dimpled grooves. Due to the unique design and process to make the proposed texture, texturing time can be greatly minimized compared to the conventional micro-groove texture technology. A computational fluid dynamics (CFD) model that considers the dimple surface angle is employed to aid the design of the texture and to predict the performance of the texture under certain conditions. Reciprocating sliding tests are preformed to evaluate the effects of the texture on friction reduction. Textures with different densities are used in the experiments. The results suggest that the dimpled groove reduces the coefficient of friction by 6% with less density distribution on the sample surface; nevertheless, denser densities may reverse the result. The simulation results suggest that the texture may perform better under pressure of the lubricant film in hydrodynamic conditions.

Tribological properties of bronze surface with dimple textures fabricated by the indentation method

Surface texturing is an effective approach to improve the tribological properties of mechanical components. An indentation method is presented to fabricate dimple textures on bronze specimen surfaces. Graphite was selected as the mating balls in ball-on-disc wear tests. The worn surfaces and the indented dimples heaped with the thin ribbon debris were observed by microscope. The morphology and evolution of wear debris were employed to explain the influence of indented dimple textures. The experimental results indicate that the generation of thin ribbon debris is due to the edge hardening of indented dimple. The thin ribbon debris and the indented conical dimple are conducive to the debris heaping on slopes of dimples, which can facilitate the formation of the graphite-rich transfer layers on indented dimple surface. Compared with nontextured surface, indented dimple surface has lower coefficients of friction and slighter wear. The tribological properties of indented dimple surface are improved because of the edge hardening, the debris heaping and the formation of transfer layers.

Numerical Study of the Influence of Geometric Features of Dimple Texture on Hydrodynamic Pressure Generation

Controlling friction and wear are essential for reducing energy loss and lengthening the life span of friction pairs in sliding contacts. Surface texturing is an effective and efficient way to reduce friction and wear, especially under lubricated conditions. Dimple texture on friction pair surfaces has been verified to enhance the lubrication condition and shift the lubrication regime by generating additional hydrodynamic pressure. However, the geometric features and distribution of the microstructures considerably influence the production of additional pressure. Choosing and designing dimple texture with suitable geometric features is necessary and important for texturing applications. In this study, computational fluid dynamics (CFD) are used to investigate the effect of the geometric features of dimple textures on pressure build-up. The influence of dimple shapes, dimple depths, minimum film thickness, dimple densities, and dimple surface angles are presented and discussed. Notably, the influence of the dimple surface angle is introduced and presented.

Research on the influence of micropits structure on the tribological performance of friction pairs

According to the traditional lubrication theory, the smoother the friction pairs the better the friction performance. But in recent years, a large number of theoretical and experimental results have shown that the friction surface with microstructure can effectively improve the tribological performance of friction pairs. For smooth surface and micro-dimple surface with different shapes of friction pairs, the two-dimensional finite element model is established based on the Navier–Stokes calculation equation of the fluid, and the effect of hydrodynamic effects arising from micro-dimple structure with different shapes on friction performance of friction pairs is analyzed. Through friction and wear testing, the friction properties of smooth surface and micro-dimple surface friction pairs are compared and analyzed. Theoretical simulation and experimental verification show that the surface of friction pairs with micropits can obviously improve the lubrication conditions of friction pairs and effectively improve the tribological properties of friction pairs.

The Influence of Micro-Texturing Dimple on the Bearing Capacity of the Elastohydrodynamic Lubrication Based on CFD-FSI Fluid-Solid Coupling

Based on the CFD-FSI fluid-solid coupled method, the equivalent elastohydrodynamic lubrication model of the micro-texturing dimple surface on the condition of the medium velocity and medium load, low velocity and heavy load, high velocity and heavy load, low velocity and light load and high velocity and light load is respectively solved by numerical method in this paper. And obtain the oil film pressure distribution curve and the oil the film thickness distribution curve on the conditions of steady state, and analyze the influence of micro-texturing dimples on the bearing capacity of the equivalent elastohydrodynamic lubrication model. Analysis results show that: compared with the corresponding minimum film thickness on the conditions of smooth surface, the minimum film thickness of micro-texturing dimple surface on the conditions of the medium velocity and medium load, low velocity and light load is increased, which indicates the bearing capacity of the equivalent elastohydrodynamic lubrication model of the micro-texturing dimple surface is increased; while the minimum film thickness of the rest conditions is decreased, which shows that the bearing capacity of the equivalent elastohydrodynamic lubrication model of the micro-texturing dimple surface is decreased. The study in this paper lays the foundation for the design and optimization of the micro-texturing dimple.