Novel In-Situ Observation of the Grease Constituents in Elastohydrodynamic Contacts by Fluorescence Microscopy

Grease is important lubricant for ball bearings as it is used much more often than oil. However, mechanism of the lubrication is not completely clear, especially concerning the role of the thickener in the lubricating process. It was shown that contribution of the thickener to film thickness build-u...

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Bibliographic Details
Published in:Tribology letters 2022-12, Vol.70 (4), Article 126
Main Authors: Kostal, David, Okal, Michal, Fryza, Josef, Krupka, Ivan, Hartl, Martin
Format: Article
Language:English
Subjects:
Ball bearings
Chemistry and Materials Science
Constituents
Corrosion and Coatings
Elastohydrodynamic lubrication
Film thickness
Fluorescence
Greases
Lubricants
Lubricants & lubrication
Lubrication
Materials Science
Nanotechnology
Physical Chemistry
Surfaces and Interfaces
Test equipment
Theoretical and Applied Mechanics
Thin Films
Tribology
Tribology Methods
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Summary:Grease is important lubricant for ball bearings as it is used much more often than oil. However, mechanism of the lubrication is not completely clear, especially concerning the role of the thickener in the lubricating process. It was shown that contribution of the thickener to film thickness build-up varies with operating conditions. Also, its influence on the resistive torque of the bearing was proved. However, all studies were in-direct showing its effects. This paper presents new in-situ fluorescence method of the grease constituents’ observation, where both, thickener, and base oil can be observed independently. Two different fluorescence dyes are used to distinguish grease constituents with the use of different microscope setup. Moreover, the new method was tested on two different test rigs. First is typical ball on disc test rig widely used for study of elastohydrodynamic lubrication. Second is ball on ring test rig which more closely represents radial ball bearing conditions. It was shown that thickener engagement is very different for each geometrical configuration.
ISSN:1023-8883
1573-2711
DOI:10.1007/s11249-022-01671-7