On the Relation between Friction Increase and Grease Thickener Entraining on a Border of Mixed EHL Lubrication

This paper deals with an experimental study of film thickness and friction of commercial-grade grease and its base oil in a highly loaded contact. In-situ measurements were conducted for two surface textures on a ball-on-disc optical tribometer at the border of mixed lubrication. At high speeds, the...

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Bibliographic Details
Published in:Lubricants 2020-02, Vol.8 (2), p.12
Main Authors: Zapletal, Tomas, Sperka, Petr, Krupka, Ivan, Hartl, Martin
Format: Article
Language:English
Subjects:
base oil
Bearings
ehl
Experiments
Film thickness
Friction
grease
Interferometry
Lubricants
Lubricants & lubrication
Lubrication
Thin films
Viscosity
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Summary:This paper deals with an experimental study of film thickness and friction of commercial-grade grease and its base oil in a highly loaded contact. In-situ measurements were conducted for two surface textures on a ball-on-disc optical tribometer at the border of mixed lubrication. At high speeds, the film thickness and the friction of grease correspond with the base oil, while, the thickener enters the contact area and locally affects the film thickness and friction at low speeds. It was found out that the thickener starts to enter the contact area approximately at the same speed when the base oil friction increases on Stribeck curve but without direct solid to solid contact. It indicates that both effects can have the same origin. Change of lubricant flow in contact inlet area was discussed as a possible explanation.
ISSN:2075-4442
2075-4442
DOI:10.3390/lubricants8020012