Optimization of tribological systems by aimed anticipation of the running-in by final machining on the example of journal bearings

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Aim of the research project is the development of a final machining process for journal bearings and its optimization by analyzing the resulting work piece subsurface layer, topography and the running-in behavior. The cutting process is investigated on the example of shaft journals (42CrMo4). Besides the finishing of journal bearing made of bronze, also high-strength materials made of steel (100Cr6, 42CrMo4) and aluminum housing material are examined on the bore-side. Hereby, the cutting process enables the aimed generation of nanocrystalline subsurface layers, which lead to a defined, short running-in behavior in the following operation. This leads to the formation of the third body with low friction and wear rates.In the second funding period a deeper understanding of the surface layer states within the nanocrystalline material is generated, thus leading to a further improvement of the tribosystem. Furthermore, the transfer of the research work onto an internal cutting process is being analyzed. Hereby, the geometries as well as the subsurface layer states of the journal shafts and bearings can be tribologically optimized. Furthermore, a practical tool for an efficient process management for the final machining is being created and the simulation models at different scales are integrated. The knowledge resulting from manufacturing and design of the bearings is finally validated in the tribological test rig.To assess the results given by simulation, experimental work on a test bench with journal bearings is necessary. Study of the tribological behavior has especially got to take place during the running-in of the bearings and in the regime of mixed lubrication. Another aspect of experimental work is the development of the turning process, which has to yield a reproducible formation of a nanocrystalline subsurface layer and an optimized topography. The adaption of process parameters to the internal cutting process is examined by tribological experiments to further improve tribological behavior.In addition to the experiments simulation is used to engage process understanding during tribological contact. The friction process is therefore examined on different length scales. Simulation of the final machining by WBK yields information on initial properties of the two bodies in contact. Those results as well as the results of the simulation by IAM-ZBS define the values used by the finite element simulation that shows the topography development during the operation of the journal bearing and its influence on the friction.