| [
Lubrication
Knowledge Menu ] [ Products
and Services Directory ]
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.
|
