"Greasing" redirects here. For the network protocol design tool, see grease (networking).
Lubrication is the process or technique of using a lubricant to reduce friction and wear and tear in a contact between two surfaces. The study of lubrication is a discipline in the field of tribology.
Lubrication of a ship's steam enginecrankshaft. The two bottles of lubricant are attached to the piston and move while the engine is operating.
Lubrication mechanisms such as fluid-lubricated systems are designed so that the applied load is partially or completely carried by hydrodynamic or hydrostatic pressure, which reduces solid body interactions (and consequently friction and wear). Depending on the degree of surface separation, different lubrication regimes can be distinguished.
Adequate lubrication allows smooth, continuous operation of machine elements, reduces the rate of wear, and prevents excessive stresses or seizures at bearings. When lubrication breaks down, components can rub destructively against each other, causing heat, local welding, destructive damage and failure.
As the load increases on the contacting surfaces, distinct situations can be observed with respect to the mode of lubrication, which are called lubrication regimes:[1]
Fluid film lubrication is the lubrication regime in which, through viscous forces, the load is fully supported by the lubricant within the space or gap between the parts in motion relative to one another object (the lubricated conjunction) and solid–solid contact is avoided.[2]
In hydrostatic lubrication, external pressure is applied to the lubricant in the bearing to maintain the fluid lubricant film where it would otherwise be squeezed out.
In hydrodynamic lubrication, the motion of the contacting surfaces, as well as the design of the bearing, pump lubricant around the bearing to maintain the lubricating film. This design of bearing may wear when started, stopped or reversed, as the lubricant film breaks down. The basis of the hydrodynamic theory of lubrication is the Reynolds equation. The governing equations of the hydrodynamic theory of lubrication and some analytical solutions can be found in the reference.[3]
Elastohydrodynamic lubrication: Mostly for nonconforming surfaces or higher load conditions, the bodies suffer elastic strains at the contact. Such strain creates a load-bearing area, which provides an almost parallel gap for the fluid to flow through. Much as in hydrodynamic lubrication, the motion of the contacting bodies generates a flow induced pressure, which acts as the bearing force over the contact area. In such high pressure regimes, the viscosity of the fluid may rise considerably. At full film elastohydrodynamic lubrication, the generated lubricant film completely separates the surfaces. Due to the strong coupling between lubricant hydrodynamic action and the elastic deformation in contacting solids, this regime of lubrication is an example of Fluid-structure interaction.[4] The classical elastohydrodynamic theory considers Reynolds equation and the elastic deflection equation to solve for the pressure and deformation in this lubrication regime.[5][6] Contact between raised solid features, or asperities, can also occur, leading to a mixed-lubrication or boundary lubrication regime.
Boundary lubrication is defined as that regime in which the load is carried by the surface asperities (high points) rather than by the lubricant.[7] This is the effect that makes Ultra-high-molecular-weight polyethylene "self-lubricating".
Boundary film lubrication:[8] The hydrodynamic effects are negligible. The bodies come into closer contact at their asperities (high points); the heat developed by the local pressures causes a condition which is called stick-slip, and some asperities break off. At the elevated temperature and pressure conditions, chemically reactive constituents of the lubricant react with the contact surface, forming a highly resistant tenacious layer or film on the moving solid surfaces (boundary film) which is capable of supporting the load and major wear or breakdown is avoided.
Mixed lubrication: This regime is in between the full film elastohydrodynamic and boundary lubrication regimes. The generated lubricant film is not enough to separate the bodies completely, but hydrodynamic effects are considerable.[9]
Besides supporting the load the lubricant may have to perform other functions as well, for instance it may cool the contact areas and remove wear products. While carrying out these functions the lubricant is constantly replaced from the contact areas either by the relative movement (hydrodynamics) or by externally induced forces.
Lubrication is required for correct operation of mechanical systems such as pistons, pumps, cams, bearings, turbines, gears, roller chains, cutting tools etc. where without lubrication the pressure between the surfaces in close proximity would generate enough heat for rapid surface damage which in a coarsened condition may literally weld the surfaces together, causing seizure.
In some applications, such as piston engines, the film between the piston and the cylinder wall also seals the combustion chamber, preventing combustion gases from escaping into the crankcase.
Automatic lubricator – Device fitted to a steam engine to supply lubricating oil.
Automatic lubrication system - A system that delivers controlled amounts of lubricant to multiple locations on a machine while the machine is operating.
Referencesedit
^Hamrock, Bernard J. (2004). Fundamentals of fluid film lubrication. Steven R. Schmid, Bo O. Jacobson (2nd ed.). New York: Marcel Dekker. ISBN0-8247-5120-5. OCLC 55739786.
^San Andrés. L. "Introduction to pump rotordynamics, Part i. Introduction to hydrodynamic lubrication". ("MEEN626 Lubrication Theory Class:Syllabus FALL2006"). [1][permanent dead link] (11 Dec 2007)
^Popova, E.; Popov, V. L. (2015). "On the history of elastohydrodynamics: The dramatic destiny of Alexander Mohrenstein-Ertel and his contribution to the theory and practice of lubrication". Zeitschrift für Angewandte Mathematik und Mechanik. 95 (7): 652–663. Bibcode:2015ZaMM...95..652P. doi:10.1002/zamm.201400050.
^Bosman R. and Schipper D.J. Microscopic Mild Wear in the Boundary Lubrication regime. Laboratory for Surface Technology and Tribology, Faculty of Engineering Technology, University of Twente, P.O. Box 217, NL 7500 AE Enschede, The Netherlands.
^Akchurin, Aydar; Bosman, Rob; Lugt, Piet M.; Drogen, Mark van (2015-05-31). "On a Model for the Prediction of the Friction Coefficient in Mixed Lubrication Based on a Load-Sharing Concept with Measured Surface Roughness". Tribology Letters. 59 (1): 19. doi:10.1007/s11249-015-0536-z. ISSN 1023-8883.
External linksedit
Wikimedia Commons has media related to Lubrication.
Look up lubrication in Wiktionary, the free dictionary.
International Council for Machinery Lubrication
January 09, 2024
lubrication, greasing, redirects, here, network, protocol, design, tool, grease, networking, process, technique, using, lubricant, reduce, friction, wear, tear, contact, between, surfaces, study, lubrication, discipline, field, tribology, ship, steam, engine, . Greasing redirects here For the network protocol design tool see grease networking Lubrication is the process or technique of using a lubricant to reduce friction and wear and tear in a contact between two surfaces The study of lubrication is a discipline in the field of tribology Lubrication of a ship s steam engine crankshaft The two bottles of lubricant are attached to the piston and move while the engine is operating This article s lead section contains information that is not included elsewhere in the article Please help improve the lead December 2021 Learn how and when to remove this template message Lubrication mechanisms such as fluid lubricated systems are designed so that the applied load is partially or completely carried by hydrodynamic or hydrostatic pressure which reduces solid body interactions and consequently friction and wear Depending on the degree of surface separation different lubrication regimes can be distinguished Adequate lubrication allows smooth continuous operation of machine elements reduces the rate of wear and prevents excessive stresses or seizures at bearings When lubrication breaks down components can rub destructively against each other causing heat local welding destructive damage and failure Contents 1 Lubrication mechanisms 1 1 Fluid lubricated systems 2 See also 3 References 4 External linksLubrication mechanisms editFluid lubricated systems edit As the load increases on the contacting surfaces distinct situations can be observed with respect to the mode of lubrication which are called lubrication regimes 1 Fluid film lubrication is the lubrication regime in which through viscous forces the load is fully supported by the lubricant within the space or gap between the parts in motion relative to one another object the lubricated conjunction and solid solid contact is avoided 2 In hydrostatic lubrication external pressure is applied to the lubricant in the bearing to maintain the fluid lubricant film where it would otherwise be squeezed out In hydrodynamic lubrication the motion of the contacting surfaces as well as the design of the bearing pump lubricant around the bearing to maintain the lubricating film This design of bearing may wear when started stopped or reversed as the lubricant film breaks down The basis of the hydrodynamic theory of lubrication is the Reynolds equation The governing equations of the hydrodynamic theory of lubrication and some analytical solutions can be found in the reference 3 Elastohydrodynamic lubrication Mostly for nonconforming surfaces or higher load conditions the bodies suffer elastic strains at the contact Such strain creates a load bearing area which provides an almost parallel gap for the fluid to flow through Much as in hydrodynamic lubrication the motion of the contacting bodies generates a flow induced pressure which acts as the bearing force over the contact area In such high pressure regimes the viscosity of the fluid may rise considerably At full film elastohydrodynamic lubrication the generated lubricant film completely separates the surfaces Due to the strong coupling between lubricant hydrodynamic action and the elastic deformation in contacting solids this regime of lubrication is an example of Fluid structure interaction 4 The classical elastohydrodynamic theory considers Reynolds equation and the elastic deflection equation to solve for the pressure and deformation in this lubrication regime 5 6 Contact between raised solid features or asperities can also occur leading to a mixed lubrication or boundary lubrication regime Boundary lubrication is defined as that regime in which the load is carried by the surface asperities high points rather than by the lubricant 7 This is the effect that makes Ultra high molecular weight polyethylene self lubricating Boundary film lubrication 8 The hydrodynamic effects are negligible The bodies come into closer contact at their asperities high points the heat developed by the local pressures causes a condition which is called stick slip and some asperities break off At the elevated temperature and pressure conditions chemically reactive constituents of the lubricant react with the contact surface forming a highly resistant tenacious layer or film on the moving solid surfaces boundary film which is capable of supporting the load and major wear or breakdown is avoided Mixed lubrication This regime is in between the full film elastohydrodynamic and boundary lubrication regimes The generated lubricant film is not enough to separate the bodies completely but hydrodynamic effects are considerable 9 Besides supporting the load the lubricant may have to perform other functions as well for instance it may cool the contact areas and remove wear products While carrying out these functions the lubricant is constantly replaced from the contact areas either by the relative movement hydrodynamics or by externally induced forces Lubrication is required for correct operation of mechanical systems such as pistons pumps cams bearings turbines gears roller chains cutting tools etc where without lubrication the pressure between the surfaces in close proximity would generate enough heat for rapid surface damage which in a coarsened condition may literally weld the surfaces together causing seizure In some applications such as piston engines the film between the piston and the cylinder wall also seals the combustion chamber preventing combustion gases from escaping into the crankcase If an engine required pressurised lubrication to say plain bearings there would be an oil pump and an oil filter On early engines such as a Sabb marine diesel where pressurised feed was not required splash lubrication would suffice See also editAutomatic lubricator Device fitted to a steam engine to supply lubricating oil Automatic lubrication system A system that delivers controlled amounts of lubricant to multiple locations on a machine while the machine is operating References edit Hamrock Bernard J 2004 Fundamentals of fluid film lubrication Steven R Schmid Bo O Jacobson 2nd ed New York Marcel Dekker ISBN 0 8247 5120 5 OCLC 55739786 San Andres L Introduction to pump rotordynamics Part i Introduction to hydrodynamic lubrication MEEN626 Lubrication Theory Class Syllabus FALL2006 1 permanent dead link 11 Dec 2007 tribonet 2017 02 16 Hydrodynamic Lubrication Tribology Retrieved 2017 02 23 Singh Kushagra Sadeghi Farshid Russell Thomas Lorenz Steven J Peterson Wyatt Villarreal Jaret Jinmon Takumi 2021 09 01 Fluid Structure Interaction Modeling of Elastohydrodynamically Lubricated Line Contacts Journal of Tribology 143 9 091602 doi 10 1115 1 4049260 ISSN 0742 4787 S2CID 230619508 tribonet 2017 02 05 Elastohydrodynamic Lubrication EHL Tribology Retrieved 2017 02 23 Popova E Popov V L 2015 On the history of elastohydrodynamics The dramatic destiny of Alexander Mohrenstein Ertel and his contribution to the theory and practice of lubrication Zeitschrift fur Angewandte Mathematik und Mechanik 95 7 652 663 Bibcode 2015ZaMM 95 652P doi 10 1002 zamm 201400050 Bosman R and Schipper D J Microscopic Mild Wear in the Boundary Lubrication regime Laboratory for Surface Technology and Tribology Faculty of Engineering Technology University of Twente P O Box 217 NL 7500 AE Enschede The Netherlands Ewen James Boundary Lubrication Trbonet Akchurin Aydar Bosman Rob Lugt Piet M Drogen Mark van 2015 05 31 On a Model for the Prediction of the Friction Coefficient in Mixed Lubrication Based on a Load Sharing Concept with Measured Surface Roughness Tribology Letters 59 1 19 doi 10 1007 s11249 015 0536 z ISSN 1023 8883 External links edit nbsp Wikimedia Commons has media related to Lubrication nbsp Look up lubrication in Wiktionary the free dictionary Machinery Lubrication magazine International Council for Machinery Lubrication Retrieved from https en wikipedia org w index php title Lubrication amp oldid 1171074685, wikipedia, wiki, book, books, library,
