On the evolution of oil-separation properties of lubricating greases under shear degradation

The bleed rate of a grease may change over time due to degradation of the thickener microstructure and a decrease in oil content, as oil is released from the grease. In this work, the bleed properties—quantified by the permeability—of five types of lubricating greases are studied. Controlled shear a...

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Bibliographic Details
Published in:Tribology international 2023-01, Vol.179, p.108154, Article 108154
Main Authors: Hogenberk, Femke, Osara, Jude A., van den Ende, Dirk, Lugt, Piet M.
Format: Article
Language:English
Subjects:
Condition monitoring
Grease
Mechanical degradation
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Summary:The bleed rate of a grease may change over time due to degradation of the thickener microstructure and a decrease in oil content, as oil is released from the grease. In this work, the bleed properties—quantified by the permeability—of five types of lubricating greases are studied. Controlled shear ageing is performed using a grease worker. It is shown that the bleed rate does not change significantly in a grease worker at room temperature, as opposed to changes in rheology and microstructure. This is explained using a permeability model. It is shown, via a comparison with rolling bearings results, that ageing grease in a grease worker is too mild to yield significant changes in the permeability of lubricating greases. •Shear ageing at room temperature does not lead to changes in bleed and permeability.•A permeability model is used to explain phenomenological observations.•Shear ageing at higher temperatures could lead to changes in permeability.
ISSN:0301-679X
1879-2464
DOI:10.1016/j.triboint.2022.108154