Lubricating Grease

lubricating grease

[′lü·brə‚kād·iŋ ‚grēs]
A solid or semisolid lubricant consisting of a thickening agent (soap or other additives) in a fluid lubricant (usually petroleum lubricating oil).
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Grease, Lubricating


a lubricant that exhibits properties of liquids or solids, depending on the stress. Under small stresses, lubricating greases preserve their structure, remain on vertical surfaces, and are retained on unsealed frictional surfaces. They consist of a liquid oil, a solid thickener (or gelling agent), and various additives. The particles of the gelling agent constitute the dispersed phase of a colloidal solution. They form a structural network of cells, which retain the dispersion medium (oil). Because of this structure, greases undergo deformation, like liquids of irregular viscosity, only under stresses in excess of their yield stress, which is usually 0.1–2 kilonewtons per m2, or 1–20 grams-force per cm2. The bonds of the structural network are restored immediately after the release of stress, and the lubricant once again assumes the properties of a solid.

The use of greases makes it possible to simplify the design and lower the weight of frictional surfaces, in addition to preventing pollution of the environment. Greases need to be replaced less frequently than ordinary lubricants; in fact, an initial application of grease often suffices for the entire service life of modern machines. In 1974, Soviet industry produced about 150 types of lubricating greases. World production totals about 1 million tons per year, which is 3.5 percent of the total production of lubricants.

Greases are produced by adding 5–30 (usually 10–20) percent of a solid thickener to petroleum oils or, less frequently, synthetic oils. The production process is of the batch type (that is, once a batch of the product has been obtained the starting materials are fed again and the production process is repeated). After being fused with the oil in a heated cauldron, the thickener crystallizes in the form of a network of fine fibers. Thickeners with melting points above 200°-300°C are dispersed in oil with the aid of homogenizers, such as colloid mills. Oxidation and rust inhibitors, antiwear agents, and other liquid additives are added to lubricating greases during manufacture, as are solid friction-reducing and sealant additives.

Greases are classified according to their gelling agents and areas of application. The most common greases are of the soap-base type, which are thickened with calcium, lithium, or sodium soaps of fatty acids of high molecular weight. Greases made with hydrated calcium can be used at temperatures of up to 60°-80°C, sodium greases can be used up to 110°C, and lithium and complex calcium greases can be used at temperatures as high as 120°-140°C. Hydrocarbon greases, thickened with paraffin or ceresin, constitute 10–15 percent of the total production of lubricating greases. They have low melting points (50°-65°C) and are mainly used for the preservation of metal articles.

Various greases are distinguished according to their uses. Antifriction greases, which lower sliding friction and reduce wear, are used in industrial machinery, instruments, and transport agricultural machinery on rolling or sliding bearings, in joints, and in gear drives and chain drives. Anticorrosion greases are used to protect metal articles. In contrast to such coatings as paint or chrome plating, grease is readily removed from frictional and other surfaces when the machine is put back into service. A third type, packing greases, includes sealants for the fittings on gate valves and stopcocks, greases that prevent threaded assemblies from seizing under heavy loads or high temperatures, and greases that are used to hermetically seal movable vacuum couplings.


Boner, C. J. Proizvodstvo i primenenie konsistentnykh smazok. Moscow, 1958. (Translated from English.)
Sinitsyn, V. V. Podbor i primenenie plastichnykh smazok, 2nd ed. Moscow, 1974.
Fuks, I. G. Plastichnye smazki. Moscow, 1972.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Appeal/Demand for Sample Report - Demand for lubricating grease has been gaining steady traction, on the back of its extensive use in the mining and automotive industries for enhancing operational performance.
With every rotation of the main shaft, it conveys the lubricating grease back into the interior, contributing to still more reduction of frictional losses.
Outside ASTM, he is a member of the European Lubricating Grease Institute, the German Institute for Standardization (DIN) and the Society of Tribologists and Lubrication Engineers.
The consistency of the grease is also an important factor to take into consideration; consistency is a measure of the grease thickness and is rated on a standard NLGI scale (National Lubricating Grease Laboratory) in numbers from 0 to 4.
A member of the American Chemical Society, Ravichandran is also active in the Society of Tribologists and Lubrication Engineers, the Society for Imaging Science & Technology, and the National Lubricating Grease Institute.
12-Hydroxy stearic acid, lithium hydroxide, and naphthenic mineral lubricating oil (density at 20[degrees]C = 916 kg/[m.sup.3]; kinematic viscosity at 40[degrees]C = 115 [mm.sup.2]/s) were used as received to prepare lithium 12-hydroxystearate lubricating grease containing 14% (w/w) soap.
Lubricating grease consistency has been evaluated for years with cone penetration test ASTM-D217.
Barbara Bellanti of Battenfeld Grease & Oil in North Tonawada, N.Y., is a past president of NLGI, an international technical trade association that serves the lubricating grease and gear lubricant industry.
The nanoceramic lubricating grease does not soften or run out; after 100,000 production strokes it shows no evidence of breaking down.