Apparent Viscosity Grease Review

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Apparent Viscosity Grease Review

Apparent viscosity: At start-up, grease has a resistance to motion, implying a high viscosity. However, as grease is sheared between wearing surfaces and moves faster, its resistance to flow reduces. Its viscosity decreases as the rate of shear increases. By contrast, an oil at constant temperature would have the same viscosity at start-up as it has when it is moving. To distinguish between the viscosity of oil and grease, the viscosity of a grease is referred to as apparent viscosity. Apparent viscosity is the viscosity of a grease that holds only for the shear rate and temperature at which the viscosity is determined.