Variation of zero entraining velocity dimple in grease-lubricated reciprocating motion

Wang, Shanshan; Wang, Jing; Han, Yiming; Liu, Weimin

doi:10.1177/1350650119842683

Cited by 5 publications

(11 citation statements)

References 32 publications

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“…Starvation is necessary to happen for a longer term, and the more viscous of the base oil and the higher the NLGI grade, the longer time the lubrication is maintained. Wang et al 26 supported the observation that the existence time of the bled oil for C3 grease is shorter than that of MP-3 grease.…”

Section: Steady-state Resultsmentioning

confidence: 82%

“…As has been pointed out by Wang et al, 26 the National Lubricating Grease Institute (NLGI) grade and the viscosity of the base oil affects not only the bled oil film formation in ZEV reciprocating motion but also the lubrication performance. Starvation is necessary to happen for a longer term, and the more viscous of the base oil and the higher the NLGI grade, the longer time the lubrication is maintained.…”

Section: Steady-state Resultsmentioning

confidence: 96%

“…Under the steady state, SRR = ∞ stands for the condition in which the two surfaces move reversely at the same speed so that the entraining velocity is zero. 26 For the reciprocation motion, the ball and/or the disk are assumed to move in the form of a triangular wave.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…In the movement of gears and ball screws, the phenomenon dominated by a sliding velocity component is very common. Aiming at the zero entrainment contact, Wang et al 26 experimentally investigated the variation of grease film thickness in reciprocating motion with the maximum surface speed higher than the critical speed. Wang et al 26 found that the thickener could hardly enter into the contact.…”

Section: Introductionmentioning

confidence: 99%

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Effects of slide-to-roll ratio and varying velocity on the lubrication performance of grease at low speed

Han

Wang

Jin

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part J:

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Under steady-state pure rolling conditions with low speed, the thickener fiber agglomerations can be maintained for a long time, generating a beneficial thicker film thickness. However, in industrial applications, motions with sliding or transient effects are very common for gears, rolling-element bearings or even chain drives, evaluation of the grease performance under such conditions is vital for determining the lubrication mechanism and designing new greases. In this project, optical interferometry experiments were carried out on a ball-disk test rig to study the disintegration time of the grease thickener agglomerations with the increase of the slide-to-roll ratio under steady-state and reciprocation motions. Under steady-state conditions, the thickener fiber agglomeration can exist for a while and the time becomes shorter with the increase of the slide-to-roll ratio above the critical speed. Below the critical speed, the thickener fiber can exist in the contact in the form of a quite thick film for a very long time under pure rolling conditions but that time is decreased with the increase of the slide-to-roll ratio. The introduction of the transient effect can further reduce the existence time of the thickener.

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Section: Steady-state Resultsmentioning

confidence: 82%

Section: Steady-state Resultsmentioning

confidence: 96%

Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of slide-to-roll ratio and varying velocity on the lubrication performance of grease at low speed

Han

Wang

Jin

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part J:

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“…Wong et al (2018) offered an idea of making the bearing surfaces different in affinity to oil to facilitate hydrodynamic lubrication for ZEV contacts. Wang et al (2019) experimentally explored the variation in grease film thickness under ZEV reciprocating motion. Their results showed that the grease consistency exerted a significant influence on the surface dimple and the starvation severity.…”

Section: Introductionmentioning

confidence: 99%

Discrepancy in oil film distribution observed in ZEV reciprocating motion

Jin

Wang

Han

et al. 2020

ILT

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Purpose This study aims to present the discrepancy in oil film distribution in reciprocating motion experimentally with zero entraining velocity (ZEV) on a conventional ball-disk test rig with oil lubrication. Design/methodology/approach Driven independently by two individual servomotors, a steel ball and a sapphire disc move at equal speed but in opposite directions in a triangle wave. The oil film images between the ball and the disc were recorded by a camera. After the experiments, the mid-section film thickness was evaluated by using a dichromatic interference intensity modulation approach. Findings The dimpled oil film in transient condition is shallower than that at steady state with the same load and velocities, and the transient dimple depth decreases with the decrease of time. The increase of the applied load offers a beneficial effect on lubrication. Boundary slippage happens in ZEV reciprocating motion. The slippage at the interface is related to the transient effect and applied load. Originality/value This study reveals the significant difference of the oil film variation in ZEV reciprocating motion, especially the complex boundary slippage at the interface of the oil and the sapphire disc. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0021

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Thermal-EHL analysis of slip/no-slip contact at high slide-to-roll ratio

Zhao

Wong

2021

Tribology International

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Variation of zero entraining velocity dimple in grease-lubricated reciprocating motion

Cited by 5 publications

References 32 publications

Effects of slide-to-roll ratio and varying velocity on the lubrication performance of grease at low speed

Effects of slide-to-roll ratio and varying velocity on the lubrication performance of grease at low speed

Discrepancy in oil film distribution observed in ZEV reciprocating motion

Thermal-EHL analysis of slip/no-slip contact at high slide-to-roll ratio

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