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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R&O (Rust-and-Oxidation Inhibited) – A term applied to highly refined industrial lubricating oils formulated for long service in circulating lubrication systems, compressors, hydraulic systems, bearing housing, gearboxes, etc. The finest R&O oils are often referred to as turbine oils.

Refining – A series of processes for converting crude oil and its fractions to finished petroleum products. Following distillation, a petroleum fraction may undergo one or more additional steps to purify or modify it. These refining steps include thermal cracking, catalytic cracking, polymerization, alkylation, reforming, hydro-cracking, hydroforming, hydrogenation, hydrogen treating, hydrofining, solvent extraction, dewaxing, deoiling, acid treating, clay filtration, and deasphalting. Refined lubricating oils may be blended with other lube stocks, and additives may be incorporated to impart special properties.

Re-Refining – A series of processes used to convert used oil into high-quality base stock.  

Rheology – The study of the deformation and flow of matter in terms of stress, strain, temperature, and time. The rheological properties of a grease are commonly measured by penetration and apparent viscosity.

Rolling Oil – An oil used in hot- or cold-rolling of ferrous and non-ferrous metals to facilitate feed of the metal between the work rolls, improve the plastic deformation of the metal, conduct heat from the metal, and extend the life of the work rolls.  Because of the pressures involved, a rolling oil may be compounded or contain EP additives. In hot rolling, the oil may also be emulsifiable.

Rust Inhibitor – A type of corrosion inhibitor used in lubricants to protect surfaces against rusting.

Rust Preventive
– A compound for coating metal surfaces with a film that protects against rust; commonly used for the preservation of equipment in storage. The base material of a rust preventive may be a petroleum oil, solvent, wax, or asphalt, to which a rust inhibitor is added. A formulation consisting largely of a solvent and additives is commonly called a thin-film rust preventive because of the thin coating that remains after evaporation of the solvent. Rust preventives are formulated for a variety of conditions of exposure (e.g., short-time “in-process” protection, indoor storage, exposed outdoor storage, etc.)