Glossary of Lubrication Terms

This glossary is designed to help the understanding of some of the terms used in Tribology and Lubrication Engineering. Quickly look up a definition or explanation for a topic.
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Naphthenic – Petroleum fluid derived from naphthenic crude oil, characterized by a high proportion of cyclo-parraffinic structures or by an absence of wax molecules.
Neutralization Number –  A number used as a measure of the acidic or basic constituents. This term is ambiguous and now obsolete. 

Newtonian Fluid – Any fluid, such as a straight mineral oil, whose viscosity does not change with rate of flow.

NLGI Automotive Grease Classifications – Automotive lubricating grease quality levels established jointly by SAE, ASTM and NLGI. There are several categories in two classifications: Chassis Lubricants and Wheel Bearing Lubricants. Quality or performance levels within each category are defined by ASTM tests.

NLGI (National Lubricating Grease Institute)
– Trade association whose main interest is grease and grease technology. NLGI is best known for its system of rating greases by penetration.

NLGI Consistency Grades – Simplified system established by the National Lubricating Grease Institute (NLGI) for rating the consistency of grease.

Non-Newtonian Fluid – Fluid, such as a grease or a polymer-containing oil (e.g., multigrade oil), in which shear stress is not proportional to shear rate.

Normal Paraffin
– A hydrocarbon consisting of molecules in which any carbon atom is attached to no more than two other carbon atoms; also called straight-chain paraffin and linear paraffin.