What is the role of film strength in hydraulic fluids?

The role of film strength in hydraulic fluids is primarily to prevent metal-to-metal contact. This film strength refers to the ability of the fluid to create a protective layer between moving surfaces, especially under high pressure and load conditions. A strong lubricating film minimizes wear and tear on components by ensuring that solid surfaces do not touch each other during operation. This is crucial for maintaining the integrity of hydraulic components and prolonging their lifespan.

While viscosity, fluid penetration, and thermal conductivity are important properties of hydraulic fluids, they do not directly relate to the specific function of film strength. Viscosity is primarily about how the fluid behaves under temperature variations, while penetration refers to the ability of the fluid to flow into small spaces or gaps. Thermal conductivity relates to the fluid's ability to conduct heat, which, while important, is not related to the formation of a protective film that prevents contact between metal surfaces.