Lifetime influence of cage pocket wear in transfer lubrication of solid-lubricated roller bearings
Final Report Abstract
In the present project, cage pocket wear in solid lubricated rolling bearings has been investigated based on experimental as well as simulative analysis. The objective of the investigation was to identify the effects of deliberately worn out cage pockets on re-lubrication phenomena of the bearings and their effects on the bearing behavior. Thus, to help in making the prognosis about the service life of these machine elements. The part objectives were performing the bearing experiments with adapted cage pocket geometries and deriving the comprehensive wear simulation model in a multibody simulation environment to reproduce the temporal wear of the cage pockets. Tribological characterization between the cage pocket/rolling element contact for material pair PIM15-Ag was presented. The results provide the necessary information about the friction and wear characteristics for material pair in contacts. It has shown that COF remains almost constant irrespective of the sliding velocities, but the wear rate showed the direct proportionality on the pressure and sliding velocity. The real component tests provided a detailed understanding of the cage pocket wear, and thus the potential lubrication effects in-case tests are run for different durations, loads, temperatures, and deliberately enlarged pocket diameters. The first results of different run-time confirmed the increasing amount of cage pocket wear with runtime. For the chosen lubrication material combination, load, and temperatures, service life behavior has been carefully observed. Moreover, cage pocket wear investigation stated that an increase in pocket diameter (clearance) eventually causes the reduction of pocket wear and resulting lubrication interval. Adaptation of the cage pocket geometries showed a substantial effect on the overall frictional torque. In addition to this, to confirm and understand the basics of the transfer process, the surface analysis was carried out. The analysis confirmed the traces of transfer of cage material onto the bearing rings and the rolling components, although no traces of transfer were found from silver-coated rolling elements onto cage pockets or on the bearing ring. In the future work, more component and tribological tests need to be carried out to deepen the understanding of the wear and transfer mechanisms at the cage pocket. This is currently being conducted in another DFG project. Apart from experimental studies, a comprehensive cage wear modeling strategy had been developed during this project. The model is useful to simulate and analyse the temporal wear progress as well as to visualize the resulting pocket evolution and several other macroscopic aspects in solid lubricated rolling bearings. The obtained tribological and experimental results had been used for the plausibility check and validation of the model. Simulation results have shown a sensible comparison with the experimental results. The influence of running duration and radial loads on the wear progression was studied and presented in detail. Recommendations could be drawn based on presented results in terms of choice and paying critical attention towards bearing cage pocket fine geometry, bearing load, and temperature conditions. However, it must be noted that the simulation of wear is based on an empirical approach. Thus, the scope of application of the employed friction and wear characteristics is limited to conditions similar to those presented in this project work. Results presented during this project should be useful for the bearing manufacturer and the user under the presented operating scenarios to make a service life prognosis of solid lubricated rolling bearings. Cage pocket wear is a complex tribological phenomenon due to the various transfer processes take place during the bearing operation, due to the interaction between the components rolling elements - cage pockets – raceways – ring guideways. Although investigating the pocket wear in all aspects like transfer in detail and to derive the transfer model by determining the factors remain by all means a significant milestone. Therefore, there is a need for further research to examine in detail the transfer processes. The controlled cage pocket wear through such transfer models should be emphasized. If this process is transferred and controlled in a targeted manner, through the remarkable potential of the cage pocket wear system, it remains the achievement in real application scenarios of these machine elements. The objective of the research project was achieved.
Publications
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"An Approach to Determine and Analyze the Wear Rates at Cage Pocket Contacts in Solid-Lubricated Rolling Bearings, " In: Tribology Transactions 62(1) (2019), Pp. 979–990, ISSN 1040-2004
Dahiwal, R.; Pörsch, S.; Löwenstein, M. and Sauer, B.
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"Determination of the Static Wear at the Cage Pockets of Solid Lubricated Rolling Bearings," In: Proceedings of The 2019 Internation Tribology Conference (ITC), Sendai, Miyagi, Japan, 2019
Dahiwal, R.; Thielen, S. and Sauer, B.
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"Effects of Unevenly Worn Cage Pockets on the Service Life of a Solid-Lubricated Rolling Bearing," In: Proceedings of The 2019 STLE Annual Meeting And Exhibition, Nashville, Tennessee, Usa, 2019
Dahiwal, R.; Pörsch, S. and Sauer, B.
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"Investigation of Cage Pocket Wear in Solid-Lubricated Rolling Bearings" In: Proceedings of The 60th Tribologie-Fachtagung (GFT) 2019, Göttingen, 11/121, ISBN: 978-3-9817451-4-6
Dahiwal, R. and Sauer B.
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"Investigation of Cage Pocket Wear in Solid-Lubricated Rolling Bearings". In: Tribologie und Schmierungstechnik, 67. Jahrgang, 1 / 2020, S. 25–32
Dahiwal, R. and Sauer B.
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"Lifetime Influence of Cage Wear During Transfer Lubrication in Solid-Lubricated Rolling Bearings" In: Proceedings of The 22nd International Colloqium Tribology (TAE Tagung), Esslingen, 2020
Dahiwal, R. and Sauer B.
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"Modeling and Simulation of Cage Wear in Solid-Lubricated Rolling Bearings," In: Tribology Online, Vol.15, No.1 (2020) 25-35, ISSN 1881-2198
Dahiwal, R.; Thielen, S. and Sauer, B.
