Modeling impact of grease mechanical ageing on bleed and permeability in rolling bearings

Aydar Akchurin*, Dirk van den Ende, Piet M. Lugt*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

9 Citations (Scopus)
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The evolution of the film thickness in a grease lubricated rolling bearings is given by a continuous process of loss and replenishment of oil in the rolling track. It is believed that in a long run, the oil film is maintained by the oil that is bleeding from grease reservoirs. The bleeding capabilities of a grease thus have an impact on the grease and/or bearing life. The ability of a grease to bleed the oil changes during the operation of the bearing due to mechanical ageing, which affects the fiber structure of the grease. In this study the lubricating grease is considered as a porous medium formed by the grease thickener and the base oil. The oil bleed behavior of a polyurea grease was explored as a function of mechanical degradation of the grease in numerous full bearing tests. The measured degradation in bleed was interpreted as an evolution of the grease matrix permeability based on Darcy's law. A grease ageing master curve was built to describe the change of permeability of the grease due to mechanical ageing.

Original languageEnglish
Article number107507
Number of pages8
JournalTribology international
Early online date26 Feb 2022
Publication statusPublished - Jun 2022


  • Grease bleed
  • Grease life
  • Grease lubrication
  • Lubricating grease
  • Rolling bearings
  • UT-Hybrid-D

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