Väliainevoitelu

Väliainevoitelu, often translated as intermediate lubrication or boundary lubrication, refers to a lubrication regime that occurs when the lubricant film is not thick enough to completely separate the moving surfaces. In this condition, direct contact between the asperities (microscopic high points) of the opposing surfaces is possible, leading to increased friction and wear. This regime lies between the ideal hydrodynamic lubrication, where a full fluid film completely separates the surfaces, and the boundary lubrication, where surface interactions are dominant.

The effectiveness of väliainevoitelu relies on the presence of boundary additives within the lubricant. These additives, such as polar compounds or long-chain fatty acids, are able to adsorb onto the metal surfaces, forming a protective molecular layer. This adsorbed layer reduces the direct metal-to-metal contact and its associated detrimental effects. When the surfaces come into close proximity, these boundary films provide a degree of protection, preventing catastrophic wear.

Several factors influence the occurrence of väliainevoitelu. These include the viscosity of the lubricant, the speed of the moving surfaces, and the load applied. At lower speeds and higher loads, the lubricant film thickness tends to decrease, pushing the lubrication regime towards väliainevoitelu. Understanding and managing this lubrication regime is crucial in many mechanical systems, such as gears, bearings, and engines, to ensure longevity and efficient operation. Proper lubricant selection and maintenance are key to either promoting full film lubrication or optimizing the performance of boundary additives in the väliainevoitelu regime.