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Mannheim University of Applied Sciences, Faculty of Mechanical Engineering
28.05.2019 | Research, Publications

Research Report Published: Screening Test Method for Lubricating Greases

The aim of this research project was to determine faster and more reliable statements on the suitability of lubricating greases in rolling bearings at high temperatures by coupling thermo-oxidative and mechanical-dynamic laboratory test methods.

For this purpose, numerous standard ageing tests for fats were carried out and evaluated at the OWI. One focus was also on the chemiluminescence method, which was the focus of industry interest at the start of the project. At KTM, the main focus was on mechanical-dynamic rolling bearing tests in a new universal multi-station rolling bearing test rig. In addition, thermal ageing tests were carried out here on various catalyst plates and evaluated by means of rheological measurements (flow curve and limit). 

The project showed the application areas and limits of the individual thermal oxidative laboratory tests as well as the simple tribological model tests. Here, the chemiluminescence method showed limits with regard to the investigation of used fats and the evaluation of different formulations using isothermal measurements. The thermogravimetric analysis made it possible to distinguish the greases used depending on the load and the load time. In addition, the activation energies determined correlated with the change in the condition of the lubricating greases. 

The tribological model tests showed only a small agreement with the rolling bearing tests. The combination of various investigations allows a practice-relevant characterization of the greases. The investigations in the rolling bearing and during thermal ageing on catalyst plates showed that with greases based on soap thickeners the thickener degeneration limits the service life and not the actual oil ageing.

The DGMK Research Report 788 was published in German language.

Research Agencies:

OWI Oel-Waerme-Institut gGmbH An-Institut der RWTH Aachen Kompetenzzentrum Tribologie Hochschule Mannheim

The IGF project 18615 N of the Research Association DGMK was funded via the AiF as part of the programme for the promotion of Industrial Collective Research (IGF) by the Federal Ministry for Economic Affairs and Energy on the basis of a resolution of the German Bundestag.