Properties of Greases

 (a)    Consistency or yield value is expressed in terms of penetration, which is explained as “the distance in tenth of millimetre that a standard cone penetrates vertically into the sample, under the standard conditions of load, time & temperature”. The value of load, temperature & time are taken respectively as 150 g, 25oC and 5 seconds. Consistency of grease based on the structure and interaction of the gelling elements in it and to some extent on the viscosity of oil utilized.

 (b)    Drop-point is the temperature at which it passes from the semi-solid to the liquid state. So this temperature finds out the upper temperature limit of the applicability of the grease.