Tribological Performance of Rolling Contacts Produced by EDM

• Applicant: Professor Dr.-Ing. Thomas Bergs, since 7/2019
• Subject Area: Production Automation and Assembly Technology
• Term: from 2017 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 387674136

Heavily loaded rolling contacts such as the tooth flank contact, are complex tribological systems whose characteristics adjust itself through the interactions between the contact partners, the lubricant and the surrounding medium. The properties of the tribological system significantly affect the application behavior in terms of friction, wear and fatigue. The rolling strength is significantly influenced by the material, the rim zone properties, surface finish, as well as the operating parameters of slip and total velocity rate. The friction results from the state of lubrication in the contact which is established in dependence on the lubricant, the temperature and the surface roughness and structure. To reduce friction and increase sustainability of highly loaded rolling contacts in particular, the surface topography is analyzed as optimization parameters in the latest research. A key result is that the filming in the rolling contact and the service life canbe improved for studies on the two-disc test by an optimized surface structure of the final processing step. Deterministic surface textures like flat cup structures yield an improved behavior in terms of friction results compared to polished surfaces. The Electric Discharge Machining EDM can produce such a surface structure through the formation of the process inherent crater landscape. In preliminary studies it could be found that tribologically favorable surface structures can be set during wire cutting through the application of suitable finishing cuts. When using a modern process a tripling of the tolerable number of load cycles in the time field strength for pitting of wire-eroded compared to ground gears occurred when sustainability test were conducted. The objective of the project includes the deduction of a knowledge-based process model for the relationship between the parameters of EDM and the resulting surfaceintegrity of the machined component. Based on physical characteristics of discharge regimes a description model is built, which forms the basis for optimizing spark erosion rim zones and surface structures. Based on this, the aim is to investigate the tribological behavior experimentally in the two-disc analogy setup and to expand the existing calculation regarding rolling fatigue on the tribological contact by including the stochastic surface structures. For integration the existing lubricant approach is extended specifically to the cross influence of deformation. Finally, the match takes place between the theoretically calculated rolling loads for EDM and grinding surface structures and experimental results to determine the future potential for optimization.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Professor Dr.-Ing. Fritz Klocke, until 6/2019