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hydrodynamic lubrication

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Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.a0006423
EISBN: 978-1-62708-192-4
.... An increase in temperature results in a change in lubricant rheology, a decrease in flow stress of surface asperities and subsurface material, and an increase in chemical reactivity between the material being deformed and the lubricant. In the drawing process, hydrodynamic lubrication is promoted...
Image
Published: 30 August 2021
Fig. 4 Schematic of the transition from (a) inadequate (boundary) lubrication at startup to (b) hydrodynamic lubrication at full speed, h is minimum separation More
Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.a0006401
EISBN: 978-1-62708-192-4
... of friction. The article details the classifications of lubrication regimes, namely, boundary, mixed, hydrodynamic, and elastohydrodynamic lubrications. It discusses the various types of lubricant materials and additives, including liquid lubricants, solid lubricants, gaseous lubricants, greases, green...
Series: ASM Handbook
Volume: 11A
Publisher: ASM International
Published: 30 August 2021
DOI: 10.31399/asm.hb.v11A.a0006806
EISBN: 978-1-62708-329-4
..., next provides an overview of bearing materials, and then presents the various lubrication mechanisms: hydrostatic, hydrodynamic, boundary lubrication, elastohydrodynamic, and squeeze-film lubrication. The article describes the effect of debris and contaminant particles in bearings. The steps involved...
Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.a0006365
EISBN: 978-1-62708-192-4
... of a lubrication film ( Ref 7 ). Under full-film lubrication, where one finds the most successful implementation of surface texturing (i.e., sliding bearings, face seals, piston rings, hard drives), the individual dimples also act as hydrodynamic pressure pockets, which increase the load-bearing capacity ( Ref 8...
Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.a0006398
EISBN: 978-1-62708-192-4
... hydrodynamically/aerodynamically by the surface velocities or hydrostatically by an externally pressurized lubricant. The bearings, depicted in configuration IV in Fig. 1 , require a continuous supply of lubricant. Such bearings are required to meet high reliability of bearing operation. With continuous...
Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.a0006427
EISBN: 978-1-62708-192-4
.../additives, and loading/speed between the contacting or rubbing surfaces. Methods of friction and wear control depend on the component. For example, metal rubbing is dominant in the valvetrain system, whereas hydrodynamic lubrication is the norm in the crankshaft and camshaft bearings. Due to the higher...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0001809
EISBN: 978-1-62708-180-1
... in bearings and presents the steps for failure analysis of sliding bearings. It also reviews the factors responsible for bearing failure with examples. aluminum alloys babbitts bronze contaminants copper-lead bearing alloys elasto-hydrodynamics failure analysis fluid-film lubrication grooves...
Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.a0006409
EISBN: 978-1-62708-192-4
... hydrodynamic lubrication, elastohydrodynamic lubrication (EHL), mixed lubrication, and boundary lubrication. In full hydrodynamic lubrication both surfaces are completely separated by a relatively thick lubricant film (1 to 100 μm, or 39 to 3940 μin.), and friction and frictional heating is entirely dominated...
Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.a0006422
EISBN: 978-1-62708-192-4
... lubrication regimes, namely boundary lubrication, mixed-film lubrication, and fluid-film lubrication. Fig. 8 Stribeck diagram used to characterize lubrication regimes. Source: Ref 15 With low η and/or v , hydrodynamic effects are discouraged, because the entrapped film thickness...
Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.a0006424
EISBN: 978-1-62708-192-4
...-to-height ratio would be less severe. In judging the suitability of lubricants, the magnitude of the forces is often of less importance than the variation of forces and the extent of die pickup. Mixed-Film Lubrication In the presence of a liquid lubricant, plasto-hydrodynamic (PHD) lubrication...
Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.a0006403
EISBN: 978-1-62708-192-4
... lubrication, which can change depending on the load, speed, lubricant viscosity, contact geometry, and surface roughness of both surfaces. Depending on the contact conditions, fluid-film lubrication can occur by the following mechanisms: Hydrodynamic lubrication , where the shape and relative motion...
Series: ASM Handbook
Volume: 14B
Publisher: ASM International
Published: 01 January 2006
DOI: 10.31399/asm.hb.v14b.a0005159
EISBN: 978-1-62708-186-3
... and workpiece. The specific regimes that are operational depend on the severity, temperature, and geometry of the deformation mode. Detailed information on lubricating mechanisms is available in Ref 1 , 2 . Thick-Film (Hydrodynamic) Lubrication Thick-film (hydrodynamic) lubrication ( Fig. 1a...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003326
EISBN: 978-1-62708-176-4
... in the hydrodynamic films generated in conformal bearings. It was assumed that the nonconformal contacts in “antifriction” bearings generated much thinner and, thus, less protective films for the contact region. The actual lubricating means for rolling bearings was thus a puzzle. However, in 1949, Grubin ( Ref 10...
Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.9781627081924
EISBN: 978-1-62708-192-4
Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.a0006431
EISBN: 978-1-62708-192-4
... behavior ( Ref 24 ). A different and opposite mechanism was proposed by Fischer and coworkers. They proposed that based on tribochemically assisted smoothening of the Si 3 N 4 and SiC surface, the newly generated surfaces can be smooth enough to promote hydrodynamic lubrication ( Ref 17 , 25 , 26...
Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.a0006369
EISBN: 978-1-62708-192-4
... °C, or −100 °F). The PFPE materials perform well under mixed and hydrodynamic lubrication regimes but are limited in boundary lubrication, especially with steel surfaces, because conventional antiwear additives are not soluble in PFPE. Fluorine from the PFPE can react with steel surfaces in boundary...
Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.a0006370
EISBN: 978-1-62708-192-4
...). In other applications, such as sheet metal hydroforming or metal extrusion, the entrainment velocity is too low to result in hydrodynamic lubrication, and better film-generating properties are desired. Lubrication effectiveness is quantified by the dimensionless film thickness parameter: (Eq 8) Λ...
Series: ASM Handbook
Volume: 2
Publisher: ASM International
Published: 01 January 1990
DOI: 10.31399/asm.hb.v02.a0001070
EISBN: 978-1-62708-162-7
... Rotation of the shaft develops a so-called hydrodynamic pressure, p , within the oil film that with correct clearance, shaft velocity, and pore structure of the bearing is able to lift the shaft so that it rides on a liquid film of oil. This is known as hydrodynamic lubrication and is a condition...
Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.a0006413
EISBN: 978-1-62708-192-4
... on the lubrication regimes under the prevailing conditions at the local contacts. Lubrication regimes at various components under most warmed-up conditions are hydrodynamic (for bearings), mostly boundary (for valve train, cam-follower), and mixed lubrication for the piston/ring-liner interface except around...