grease types and grades pdf

Grease Types And Grades Pdf

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A lubricant user can order his motor oils for a variety of different types of engine by specifications which are internationally recognised, but he cannot do this with many of his industrial lubricants and, except for NLGI consistency numbers, he cannot do it at all for his greases.

Nomenclature of Lubricating Grease

Grease is a solid or semisolid lubricant formed as a dispersion of thickening agents in a liquid lubricant. Grease generally consists of a soap emulsified with mineral or vegetable oil. A common feature of greases is that they possess a high initial viscosity , which upon the application of shear, drops to give the effect of an oil-lubricated bearing of approximately the same viscosity as the base oil used in the grease.

This change in viscosity is called shear thinning. Grease is sometimes used to describe lubricating materials that are simply soft solids or high viscosity liquids, but these materials do not exhibit the shear-thinning properties characteristic of the classical grease. For example, petroleum jellies such as Vaseline are not generally classified as greases. Greases are applied to mechanisms that can be lubricated only infrequently and where a lubricating oil would not stay in position.

They also act as sealants to prevent ingress of water and incompressible materials. Grease-lubricated bearings have greater frictional characteristics because of their high viscosity. After sufficient force to shear the grease has been applied, the viscosity drops and approaches that of the base lubricant, such as the mineral oil.

This sudden drop in shear force means that grease is considered a plastic fluid , and the reduction of shear force with time makes it thixotropic. A few greases are rheotropic , meaning they become more viscous when worked. Soaps are the most common emulsifying agent used, and the selection of the type of soap is determined by the application. Fatty acids derivatives other than stearates are also used, especially lithium hydroxystearate.

The nature of the soaps influences the temperature resistance relating to the viscosity , water resistance, and chemical stability of the resulting grease. Calcium sulphonates and polyureas are increasingly common grease thickeners not based on metallic soaps.

Powdered solids may also be used as thickeners, especially as clays. Fatty oil-based greases have also been prepared with other thickeners, such as tar , graphite , or mica , which also increase the durability of the grease. Silicone greases are generally thickened with silica. Lithium-based greases are the most commonly used; sodium and lithium-based greases have higher melting point dropping point than calcium-based greases but are not resistant to the action of water.

The amount of grease in a sample can be determined in a laboratory by extraction with a solvent followed by e. Some greases are labeled "EP", which indicates "extreme pressure". Under high pressure or shock loading, normal grease can be compressed to the extent that the greased parts come into physical contact, causing friction and wear. EP greases have increased resistance to film breakdown, form sacrificial coatings on the metal surface to protect if the film does break down, or include solid lubricants such as graphite or molybdenum disulfide to provide protection even without any grease remaining.

These compounds are working as a release agent. Solid additives will cause increased wear in bearings. Grease from the early Egyptian or Roman eras is thought to have been prepared by combining lime with olive oil. The lime saponifies some of the triglyceride that comprises oil to give a calcium grease. In the middle of the 19th century, soaps were intentionally added as thickeners to oils. For example, black slugs Arion ater were used as axle -grease to lubricate wooden axle-trees or carts in Sweden.

A given performance category may include greases of different consistencies. The measure of the consistency of grease is commonly expressed by its NLGI consistency number. It assigns a single multi-part code to each grease based on its operational properties including temperature range, effects of water, load, etc. Silicone grease is based on a silicone oil , usually thickened with amorphous fumed silica.

Fluoropolymers containing C-O-C ether with fluorine F bonded to the carbon. They are more flexible and often used in demanding environments due to their inertness. Fomblin by Solvay Solexis and Krytox by duPont are prominent examples.

Apiezon, silicone-based, and fluoroether-based greases are all used commonly in laboratories for lubricating stopcocks and ground glass joints. The grease helps to prevent joints from "freezing", as well as ensuring high vacuum systems are properly sealed.

Apiezon or similar hydrocarbon based greases are the cheapest, and most suitable for high vacuum applications. However, they dissolve in many organic solvents.

This quality makes clean-up with pentane or hexanes trivial, but also easily leads to contamination of reaction mixtures. Silicone-based greases are cheaper than fluoroether-based greases. Silicone-based greases are not easily removed with solvent, but they are removed efficiently by soaking in a base bath.

Fluoroether-based greases are inert to many substances including solvents, acids , bases , and oxidizers. They are, however, expensive, and are not easily cleaned away. Food-grade greases are those greases that come in contact with food. Food-grade lubricant base oil are generally low sulfur petrochemical, less easily oxidized and emulsified.

H1 lubricants are food-grade lubricants used in food-processing environments where there is the possibility of incidental food contact. H2 lubricants are industrial lubricants used on equipment and machine parts in locations with no possibility of contact. H3 lubricants are food-grade lubricants, typically edible oils, used to prevent rust on hooks, trolleys and similar equipment. In some cases, the lubrication and high viscosity of a grease are desired in situations where non-toxic, non-oil based materials are required.

Carboxymethyl cellulose , or CMC, is one popular material used to create a water-based analog of greases. CMC serves to both thicken the solution and add a lubricating effect, and often silicone-based lubricants are added for additional lubrication. The most familiar example of this type of lubricant, used as a surgical and personal lubricant , is K-Y Jelly. Cork grease is a lubricant used to lubricate cork, for example in musical wind instruments.

From Wikipedia, the free encyclopedia. Main article: Silicone grease. See also: Laboratory glassware. Main article: Cork grease. Encyclopedia of Lubricants and Lubrication. Shaft Seals for Dynamic Applications. CRC Press. Nailen, Engineering Editor April Electrical Apparatus. Archived from the original on Retrieved Caines; Roger F. Haycock; John E. Hillier Automotive Lubricants Reference Book.

Engineering Materials and Application. Trans Tech Publications Ltd. TemaNord Archived from the original PDF on Journal of Ethnobiology. Fuels and lubricants handbook: technology, properties, performance, and testing volume 1. ASTM International. Significance of tests for petroleum products. The Journal of Organic Chemistry. CS1 maint: archived copy as title link. Categories : Greases Tribology. Hidden categories: CS1 maint: archived copy as title All articles with unsourced statements Articles with unsourced statements from November Articles with unsourced statements from June CS1 errors: missing title Wikipedia articles incorporating text from Grocer's Encyclopedia.

Namespaces Article Talk. Views Read Edit View history. Help Learn to edit Community portal Recent changes Upload file. Download as PDF Printable version.

Grease (lubricant)

Grease is a solid or semisolid lubricant formed as a dispersion of thickening agents in a liquid lubricant. Grease generally consists of a soap emulsified with mineral or vegetable oil. A common feature of greases is that they possess a high initial viscosity , which upon the application of shear, drops to give the effect of an oil-lubricated bearing of approximately the same viscosity as the base oil used in the grease. This change in viscosity is called shear thinning. Grease is sometimes used to describe lubricating materials that are simply soft solids or high viscosity liquids, but these materials do not exhibit the shear-thinning properties characteristic of the classical grease.

Choosing the right consistency of grease for an application is critical, as a grease that is too soft may migrate away from the area that needs to be lubricated, while a grease that is too stiff may not effectively migrate into the areas that need to be lubricated. The penetration test measures how deep a standard cone falls into a grease sample in the tenths of millimeters. Each NLGI grade corresponds to a specific worked penetration value range. Higher penetration values, such as those over , indicate a lower NLGI grade number. The NLGI scale ranges from semi-fluid to 6 solid block like a cheddar cheese spread.

Need to Know: Grease Consistency

You might be using a high-quality grease. You may have put a lot of effort and money into selecting the best quality grease in the pursuit of lubrication excellence. Considering this lubricating oil analogy, the best quality turbine oil would most likely not make a good engine oil. Most users are aware of the importance of selecting the right lubricant for a given application.

Oils can be separated into multigrade oils and monograde oils. Multigrade oils must fulfill two viscosity specifications, their viscosity grade consists of two numbers, e. Currently, most automotive engine oils are multigrade oils, while oils for restricted usage, e. While the two numbers specify the SAE viscosity grade, the viscosity index shows the temperature related change of viscosity.

Step-by-Step Grease Selection

Frequently used in lubricating food machinery.

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Он попытался что-то сказать, но Сьюзан была полна решимости. Ей хотелось поскорее оказаться в Третьем узле, и она достаточно хорошо изучила своего шефа, чтобы знать: Стратмор никуда не уйдет, пока она не разыщет ключ, спрятанный где-то в компьютере Хейла.

О Боже, пожалуйста. Не. ГЛАВА 65 Бринкерхофф мерил шагами кабинет Мидж Милкен. - Никому не позволено действовать в обход фильтров. - Ошибаешься, - возразила .

Хейл хмыкнул себе под нос и убрал упаковку тофу. Затем взял бутылку оливкового масла и прямо из горлышка отпил несколько глотков.

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1) SKF food grade and biodegradable lubricants offer a two-year shelf-life from the date of production. The basic bearing grease selection chart provides you with The 4-ball weld load test rig uses three steel balls held in a cup. A fourth.

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