CRC Handbook of Lubrication (Theory and Practice of Tribology), Volume II, Theory and Design

Booser, E. Richard; Maki, E. R.; Rosenberg, Richard C.

doi:10.1115/1.3260980

Cited by 48 publications

(24 citation statements)

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“…For all lubricants there is a shift from a low coefficient-of-friction at 1 N to a higher coefficient-of-friction at 10 N that remains relatively stable to the higher loads. This may be due to a change in lubrication regime from the hydrodynamic regime at low loads, where a lubricant film supports the load, through a elastohydrodynamic region, where metal asperities begin to come in contact, until, at high loads there is increased metal-on-metal contact, causing increased friction and resulting in the formation of boundary layers [6]. Since the lowest load available was 1 N, it is difficult to tell if the coefficient-of-friction could be further reduced, so even the initial wear condition undertaken here may be borderline in the elastohydrodynamic region.…”

Section: Wear Testsmentioning

confidence: 97%

“…At increased loads, the moving parts begin to come into contact with each other as the lubricant is squeezed out from between them [5]. When the moving parts begin to come into contact it has been shown that oil additives with long polar molecules, that bond to the surface of the moving parts, work well to reduce friction and wear [6,7]. At higher contact pressures, where material contact increases, extreme pressure additives in oils, such as zincdialkyl-dithiophosphate (ZDDP) for steels, are thought to break down, as a result of the pressure.…”

Section: Introductionmentioning

confidence: 99%

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Transition in Wear Performance for Ionic Liquid Lubricants under Increasing Load

et al. 2010

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The effect of ionic liquid (IL) lubrication for aluminium/steel systems is highly dependant on the applied load and the IL structure. This study illustrates that a change in anion of an IL lubricant results in different physicochemical properties that will alter its performance at a given load. As the load is increased there is a shift in lubricant performance and mechanism of the IL. Up to a load of 30 N the lowest wear coefficient was achieved by a phosphonium diphenylphosphate IL, whilst above 30 N a phosphonium bis(trifluoromethanesulfonyl)amide IL was able to form a more tenacious tribolayer that resulted in the lowest wear.

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Section: Wear Testsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Transition in Wear Performance for Ionic Liquid Lubricants under Increasing Load

et al. 2010

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“…9. A two-degree-of-freedom discrete model axial stiffness and damping are linearly proportional to fluid viscosity (Booser 1984). Thus from Table 3, the axial stiffness and damping of spindle A are higher than those of spindle B.…”

Section: Experimental Testmentioning

confidence: 90%

Effects of thrust hydrodynamic bearing stiffness and damping on disk-spindle axial vibration in hard disk drives

Jintanawan

Zhu

2004

Microsystem Technologies

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This paper aims at investigating the effects of variations in thrust hydrodynamic bearing (HDB) parameters such as axial stiffness and damping coefficients on the axial vibration of disk-spindle systems in hard disk drives. For a parametric study, a closed-form axial frequency response function (FRF) of HDB spindle systems is derived as a function of the axial stiffness and damping coefficients of thrust HDBs. It is known that the axial vibration of the disk-spindle system is composed of two main parts: the vibration of the rigid hub in the axial direction and the disk deflection in the transverse direction. The results from this research clearly show that the vibration amplitudes at low frequency range is dominated by the axial vibration of the hub, and the amplitude of the unbalanced (0,0) mode is dominated by the disk deflection. The parametric study reveals that at low frequency range an increase in the bearing stiffness significantly reduces the hub axial vibration, and hence the axial vibration of the disk-spindle system. Surprisingly, a too much increase in the damping results in a higher amplitude of the unbalanced (0,0) mode. This is because a heavy damping constrains the hub vibration to nearly no motion, resulting in a direct transmission of vibration from the base to disk. To confirm the parametric study, a vibration test was performed on two HDB spindle motors with identical design but different fluid viscosity. The higher viscosity represents the higher axial stiffness and damping in the thrust bearing. The test result indicates that the spindle motor with higher viscosity has a larger unbalanced (0,0) mode amplitude when subjected to an axial base excitation. IntroductionCurrently, hydrodynamic bearing (HDB) spindle motors are widely used in hard disk drives (HDDs) because of their capabilities for vibration suppression and acoustic noise reduction. Design criteria for the HDB spindles are reliability, low power consumption, and low vibration and shock responses (Asada et al. 2001; Matsuoka et al. 2001). As the spin speed and the density of HDD increase, the design of both radial and thrust bearings are a key to minimize the vibration of the HDB spindles. The radial HDBs are designed to suppress the rocking vibration which is the major contribution to track misregistration (Jintanawan 2002). The thrust HDBs have an impact not only on the rocking vibration but also on the axial vibration. The thrust HDBs provide rocking restoring and damping moments as well as axial restoring and damping forces. However only the axial forces have a great effect on the axial vibration. Suppression of this axial vibration through optimization of the thrust HDB parameters would be a practical and inexpensive solution. Experimental study on the effect of the thrust HDBs on the axial vibration of the disk-spindle systems for HDD was conducted by Ku (1997). In his study, the disk-spindle systems with four types of thrust HDBs, representing different compliance or stiffness, were tested. He has concluded that the complianc...

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“…This phenomenon can be attributed to surface fatigue [68]. Due to the repeated plastic deformation, sheetlike particles were gradually generated and separated from the coating.…”

Section: Wearmentioning

confidence: 98%

The Potential of Tribological Application of DLC/MoS2 Coated Sealing Materials

et al. 2018

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Abstract:The potential of the combination of hard and soft coating on elastomers was investigated. Diamond-like carbon (DLC), molybdenum disulfide (MoS 2 ) and composite coatings of these two materials with various DLC/MoS 2 ratios were deposited on four elastomeric substrates by means of the magnetron sputtering method. The microstructures, surface energy of the coatings, and substrates were characterized by scanning electron microscopy (SEM) and contact angle, respectively. The chemical composition was identified by X-ray Photoelectron Spectroscopy (XPS). A ball on disc configuration was used as the model test, which was performed under dry and lubricated conditions. Based on the results from the model tests, the best coating was selected for each substrate and subsequently verified in component-like test. There is not one coating that is optimal for all substrates. Many factors can affect the coatings performance. The topography and the rigidity of the substrates are the key factors. However, the adhesion between coatings and substrates, and also the coating processes, can impact significantly on the coatings performance.

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CRC Handbook of Lubrication (Theory and Practice of Tribology), Volume II, Theory and Design

Cited by 48 publications

References 0 publications

Transition in Wear Performance for Ionic Liquid Lubricants under Increasing Load

Transition in Wear Performance for Ionic Liquid Lubricants under Increasing Load

Effects of thrust hydrodynamic bearing stiffness and damping on disk-spindle axial vibration in hard disk drives

The Potential of Tribological Application of DLC/MoS2 Coated Sealing Materials

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