Influence of temperature on wear performance of greases in rolling bearings
Industrial Lubrication and Tribology
ISSN: 0036-8792
Article publication date: 3 August 2021
Issue publication date: 9 September 2021
Abstract
Purpose
Rolling bearing operation under mixed and boundary lubrication conditions may lead to heavy adhesive or abrasive wear, which may lead to wear-induced rolling bearing failure. The purpose of this paper is to investigate the wear protection capabilities of different grease compositions at varying temperatures. It is considered that the temperature influences the lubrication conditions, the behaviour of grease components, namely, bleed oil and thickener, as well as the tribofilm formation due to tribo-chemical interactions between additives and surfaces.
Design/methodology/approach
In this study, four different greases were produced on the basis of a mineral base oil by varying the thickener and the addition of ZDDP. Various grease-lubricated rolling bearing experiments were conducted in a wide temperature range from 0°C to 120°C. Subsequently, the wear pattern, tribofilm formation and grease structures were analysed. Thereby, the influence of the different grease thickeners and the performance of ZDDP as a common antiwear and extreme pressure additive was evaluated.
Findings
The results show a strong temperature-dependency and allow a classification of temperature ranges concerning wear protection. At low temperatures, all greases provide a very good wear protection without the evidence of additive-based tribofilm formation. In the experiments at elevated temperatures, ZDDP tribofilms were formed. The formation depends on the thickener type: in comparison to lithium thickener, polyurea thickener favours more protective tribofilms at the same temperature. The experimental results show that medium temperatures in the range of 40°C–60°C are critical concerning wear due to the insufficient tribolayer formation and limited load carrying capacity of the grease.
Originality/value
Temperature is a key operating parameter for grease lubrication in roller bearings. The experimental work enables consideration of different impact pathways of temperature by combining roller bearing tests and microanalysis.
Keywords
Acknowledgements
The authors would like to thank the German Society for Petroleum and Coal Science and Technology DGMK (Deutsche Wissenschaftliche Gesellschaft für Erdöl, Erdgas und Kohle e.V.) as well as the participating member companies for the support of the IGF project 19279 N, which is funded by the German Federation of Industrial Research Associations AiF (Arbeitsgemeinschaft industrieller Forschungsvereinigungen) within the framework of the program for the promotion of the Collective Industrial Research IGF (Industrielle Gemeinschaftsforschung) by the Federal Ministry for Economic Affairs and Energy BMWi (Bundesministerium für Wirtschaft und Energie) based on a resolution of the German Bundestag.
Citation
Rosenkranz, L., Richter, S., Jacobs, G., Mikitisin, A., Mayer, J., Stratmann, A. and König, F. (2021), "Influence of temperature on wear performance of greases in rolling bearings", Industrial Lubrication and Tribology, Vol. 73 No. 6, pp. 862-871. https://doi.org/10.1108/ILT-03-2021-0076
Publisher
:Emerald Publishing Limited
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