mengsmering

Mengsmering, literally “mixed lubrication” in Dutch, is a lubrication regime in tribology where the contact between two surfaces involves both a lubricating film and direct asperity contact. In this regime, the lubricant film partially supports the load, while surface roughness causes solid-to-solid contact, so friction and wear are governed by both hydrodynamic (or elastohydrodynamic) film behavior and boundary effects. The film thickness is typically comparable to the scale of surface roughness.

Mengsmering occurs at intermediate speeds and loads, when the film is thick enough to reduce some wear but not thick enough to fully separate the surfaces. Consequently, friction levels are higher than in full-film hydrodynamic lubrication and wear can occur at roughened asperities. The regime is of particular importance for components where load, speed, and surface finishes place them between boundary lubrication and full-film conditions, such as when operating conditions vary or during start-up and shut-down.

Modeling mengsmering combines fluid-film theory with contact mechanics. Predictions often couple Reynolds-type equations for the lubricating film with asperity contact models, to estimate film thickness, friction, and local wear. Experimental studies use tribometer tests and surface analyses to characterize transitions between boundary, mixed, and full-film regimes.

Applications are widespread in machinery such as gears, journal bearings, piston rings, and seals. Design strategies to optimize mengsmering include selecting appropriate lubricant viscosity and temperature range, improving surface finishes, and applying coatings to reduce asperity interactions, thereby steering operation toward more favorable lubrication regimes.