Friction Reduction of Oil-impregnated Sintered Bearings by Surface Texturing

In this study, to reduce the friction of oil-impregnated sintered bearings, rounded-rectangle dimples are processed on the bearing surface and the bearing properties are examined. The dimpled bearings achieved lower friction than the flat bearings without dimple processing. To investigate the mechanism of friction reduction of the dimpled bearings, the friction coefficient, the eccentricity ratio, and the attitude angle of the bearings were measured. As a result, the dimpled bearings showed a larger eccentricity ratio and a smaller attitude angle than the flat bearings. In addition, the attitude angles of the dimpled bearings were negative in some cases. The reason for the reduced friction of the dimpled bearings is presumed to be that the extent of the lubricating oil in the bearing clearance was narrower, while the dimple enabled a sufficient amount of lubricating oil to be supplied to the plateau region.