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Grease is a lubricant of higher viscosity than oil, consisting originally of a calcium, sodium or lithium soap jelly emulsified with mineral oil. Greases are employed where heavy pressures exist, where oil drip from the bearings is undesirable, and where the motions of the contacting surfaces is discontinuous so that it is difficult to maintain a separating film in the bearing. Grease-lubricated bearings have greater frictional characteristics at the beginning of operation, causing a temperature rise which tends to melt the grease and give the effect of an oil-lubricated bearing. Calcium and sodium base greases are the most commonly used; sodium base greases have higher melting point than calcium base greases but are not resistant to the action of water. Lithium based grease has a drip temperature at 350° to 400°F and it resists moisture hence it is commonly used as lubricant in household products such as garage door openers. GraphiteGraphite is one of the allotropes of carbon. See also allotropes of carbon. Unlike diamond, graphite is a conductor, and can be used, for instance, as the material in the electrodes of an electrical arc lamp. The pi orbital electrons delocalized across th, either by itself or mixed with grease, is also employed as a lubricant. TeflonTeflon is the brand name of a polymer compound discovered by Roy J. Plunkett ( 1910- 1994) of DuPont in 1938 and introduced as a commercial product in 1946. Teflon is polytetra fluoro ethene (PTFE). F F | | R C C R | | F F Teflon is also used as the trade is added to some greases to improve on the lubricating property. Gear greases consist of rosinRosin is a solid form of resin obtained from pines and some other plants, mostly conifers, produced by heating fresh liquid resin to vapourise the volatile liquid terpene components. It is semi-transparent and varies in color from yellow to black. At room oil, thickened with limeProperties General Name Calcium oxide Chemical formula Ca O Appearance White solid Physical Formula weight 56. 1 amu Melting point 3200 K (2927 °C) Boiling point 3773 K (3500 °C) Density 3. 3 ×103 kg/ m3 Crystal structure NaCl Solubility hydrolysed Thermo and mixed with mineral oil, with some percentage of water. Special purpose greases contain glycerol and sorbitan ester s. They are used, for example, in low-temperature conditions.

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 grease contains solid lubricants, usually graphiteGraphite is one of the allotropes of carbon. See also allotropes of carbon. Unlike diamond, graphite is a conductor, and can be used, for instance, as the material in the electrodes of an electrical arc lamp. The pi orbital electrons delocalized across th and/or molyMoly is an abbreviation for the element Molybdenum, and usually refers to the lubricant Molybdenum disulfide., to provide protection under heavy loadings. The solid lubricants bond to the surface of the metal, and prevent metal to metal contact and the resulting friction and wear when the lubricant film gets too thin.

Some siliconeSilicones or polysiloxanes , are inorganic polymers consisting of a silicon- oxygen backbone (. Si-O-Si-O-Si-O-. with side groups attached to the silicon atoms. Certain organic side groups can be used to link two or more of these -Si-O- backbones together-based lubricants are also marketed as grease. Whether they can be classified as grease in the regular sense is uncertain. Silicone grease is an amorphous fumed, silica thickened, polysiloxane-based compound.

Some renderThe verb to render has a number of meanings: As used in computer rendering. To interpret, to give an interpretation or rendition of; to calculate an image. Often used in connection with computer graphics or 3D computer graphics to describe the process ofed animal fats are known as greases. Rendered chicken fat becomes the commodity known as yellow grease. Animal greases may have been used as lubricants in the past, but this is not now common in developed nations.