LUBRICANTA LUBRICANT-(sometimes referred to as "lube") is a substance (often a liquid) introduced between two moving surfaces to reduce the friction between them, improving efficiency and reducing wear. -have the function of dissolving foreign particles. Petroleum-based lubricants like aseline tend to dissolve petroleum products such as rubber and plastic! water-based lubricants will dissolve polar chemicals! silicone-based lubricants can breakdown silicone toys.-it protects the internal combustion engines in motor vehicles and powered equipment. -contain "#$ base oil (most often petroleum fractions, called mineral oils) and less than %#$ additives. egetable oils or synthetic liquids such as hydrogenated polyolefins, esters, silicone, fluorocarbons and many others are sometimes used as base oils. -&ubricants are comprised of a base fluid, usually of petroleum origin, combined with added chemicals that enhance performance. 'ase fluids are collected from two main sources. (efined crude oil or a mi)ture of chemical compounds that perform the same task. P*(P+,- or .*/012+/ +. 3 &*'(203/145eep moving parts apart4(educe friction41ransfer heat40arry away contaminants 6 debris41ransmit power4Protect against wear4Prevent corrosion4,eal for gasses4,top the risk of smoke and fire of ob7ects KEEP MOVING PARTS APART&ubricants are typically used to separate moving parts in a system. 1his has the benefit of reducing friction and surface fatigue together with reduced heat generation, operating noise and vibrations. &ubricants achieve this by several ways. 1he most common is by forming a physical barrier i.e. a thin layer of lubricant separates the moving parts. 1his is termed hydrodynamic lubrication. 2n cases of high surface pressures or temperatures the fluid film is much thinner and some of the forces are transmitted between the surfaces through the lubricant. 1his is termed elasto-hydrodynamic lubrication. Reduce friction1ypically the lubricant-to-surface friction is much less than surface-to-surface friction in a system without any lubrication. 1hus use of a lubricant reduces the overall system friction. (educed friction has the benefit of reducing heat generation and reduced formation of wear particles as well as improved efficiency. &ubricants may contain additives known as friction modifiers that chemically bind to metal surfaces to reduce surface friction even when there is insufficient bulk lubricant present for hydrodynamic lubrication, e.g. protecting the valve train in a car engine at startup. Transfer heat'oth gas and liquid lubricants can transfer heat. 8owever, liquid lubricants are much more effective on account of their high specific heat capacity. 1his circulating flow also determines the amount of heat that is carried away in any given unit of time. 8igh flow systems can carry away a lot of heat and have the additional benefit of reducing the thermal stress on the lubricant. 1hus lower cost liquid lubricants may be used. 1he primary drawback is that high flows typically require larger sumps and bigger cooling units. 3 secondary drawback is that a high flow system that relies on the flow rate to protect the lubricant from thermal stress is susceptible to catastrophic failure during sudden system shut downs. 3n automotive oil-cooled turbocharger is a typical e)ample. 1urbochargers get red hot during operation and the oil that is cooling them only survives as its residence time in the system is very short i.e. high flow rate.Carr a!a conta"inants and de#ris&ubricant circulation systems have the benefit of carrying away internally generated debris and e)ternal contaminants that get introduced into the system to a filter where they can be removed. &ubricants for machines that regularly generate debris or contaminants such as automotive engines typically contain detergent and dispersant additives to assist in debris and contaminant transport to the filter and removal. +ver time the filter will get clogged and require cleaning or replacement, hence the recommendation to change a car9s oil filter at the same time as changing the oil. 2n closed systems such as gear bo)es the filter may be supplemented by a magnet to attract any iron fines that get created. Poor filtration significantly reduces the life of the machine (engine) as well as making the system inefficient. Trans"it $o!erPascal9s law is at the heart of hydrostatic power transmission. 8ydraulic fluids comprise a large portion of all lubricants produced in the world.Protect a%ainst !ear&ubricants prevent wear by keeping the moving parts apart. &ubricants may also contain anti-wear or e)treme pressure additives to boost their performance against wear and fatigue&Pre'ent corrosion:ood quality lubricants are typically formulated with additives that form chemical bonds with surfaces to prevent corrosion and rust.&Sea( for %asses&ubricants will occupy the clearance between moving parts through the capillary force, thus sealing the clearance. 1his effect can be used to seal pistons and shafts. T$es of (u#ricants- &iquid including emulsions and suspensions- ,olid- :reases- 3dhesive Li)uid (u#ricants&anolin (wool grease, natural water repellant);ater"#$ and?or sulphur @#.#A$, and ,ociety of 3utomotive -ngineers (,3-) viscosity inde) (2) B @C# to >%D#-