General information of lubricating greases
Greases may be defined as a solid to semi-solid material produced by the dispersion of a thickening agent in a liquid lubricant. the properties of a grease depend on the nature and amount of the thickener and of any additives used, the characteristics of the base oil, and the way in which the grease in made.
Greases are usually identified as to consistency by the NLGI grades are defined as ranges of the 60-stroke worked penetration at 250C and indicates softness or stiffness of a grease (consistency). The penetration is not a measure of the internal friction of the grease, the better are its sealing properties.