Study on mixed elastohydrodynamic lubrication of spiral bevel gears considering surface roughness

Purpose During the manufacturing process of spiral bevel gears, certain surface roughness is inevitably generated on tooth surfaces. In elastohydrodynamic lubrication (EHL), surface roughness directly influences film thickness distribution, thereby altering pressure distribution. The objective of this study is to investigate the effects of surface roughness characteristics on the lubrication performance of spiral bevel gears. Design/methodology/approach A mixed EHL model was established for spiral bevel gears through two-dimensional digital filtering numerical simulation of rough surfaces and experimental measurement of surface topography. This model enables systematic investigation of oil film pressure, film thickness and temperature distribution characteristics on gear tooth surfaces with varying surface roughness parameters. Findings Surface roughness significantly affects the lubrication performance of spiral bevel gear tooth surfaces. Larger root mean square (RMS) values of rough surfaces lead to increased oil film pressure and temperature, while reducing the minimum film thickness at the necking location. When surface texture orientation conflicts with lubricant flow direction, substantial impacts on lubrication characteristics are observed. Ground surfaces exhibit film thickness characteristics closest to numerically simulated rough surfaces, whereas milled surfaces demonstrate smaller minimum film thicknesses. Originality/value Developing a mixed EHL model for spiral bevel gears that integrates numerically simulated roughness and measured real topography data. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2025-0162/