Modeling of the tribological behavior of ground piston rods with EW2C coating in reciprocating sealing systems

• Applicants: Professor Dr.-Ing. Thomas Bergs; Professorin Dr.-Ing. Katharina Schmitz
• Subject Area: Engineering Design, Machine Elements, Product Development ; Metal-Cutting and Abrasive Manufacturing Engineering
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 574061250

For pressure buildup in hydraulic linear actuators, the application-specific use of reciprocating seals is of great importance. The tribological contact between the piston rod and the reciprocating seal significantly determines the power loss and dynamic behavior of these systems. The tribology in the sealing contact depends on the fluid, the seal, the relative velocity and, in particular, on the properties of the sealing counter surface. These properties result from the material behavior and the process inputs during the fine machining of these surfaces. The fine machining is usually performed by grinding. Usually, the surfaces of the material are hard-chrome plated. However, due to the use of chromium VI, which is harmful to health, this coating process is now only permitted under transitional regulations. Therefore, alternative coating processes are currently being sought. One possible alternative is Express Wire Coil Cladding (EW2C), an innovative manufacturing process for the resource-efficient and environmentally friendly application of protective coatings against abrasive and corrosive wear, e.g. made of Inconel. However, as is the case for most alternative coating processes, both their cutting behavior during fine machining and the tribological behavior of the ground surfaces in sealing contacts are as yet unknown. Previous findings on the relationship between the surface properties of piston rods and tribological behavior, as well as design recommendations, have been predominantly limited to uncoated or hard-chrome plated steel counter surfaces. In an interdisciplinary collaboration between the Institute for Fluid Power Drives and Systems ifas and the Laboratory for Machine Tools and Production Engineering WZL of RWTH Aachen University, the relationship between the process input variables during grinding and the tribological behavior in sealing contact are therefore to be investigated for the first time for alternatively coated sealing counter surfaces using the EW2C process as an example. The aim is to use a combined experimental and simulative research methodology to create the knowledge base for the resource-saving production of innovatively coated sealing counter surfaces.

• DFG Programme: Research Grants