InPUT – Inline process monitoring of forming processes using tribological systems

The aim of the research project is to develop an inline-capable in-situ process monitoring of temperature and lubricant distribution for cold forging. Inline process monitoring is achieved by integrating UV and thermochromatic indicators into the lubricant, allowing to record the coating thickness and temperature directly at the interface between the workpiece and the die. With the aid of process analytics, the lubricant and temperature distribution can be determined with spatial resolution and fed back to upstream and downstream processes (figure 1).

Coordinator: Christoph Kuhn M. Sc.
Duration: June 2020 – May 2023
Funded by: BMWK Im Rahmen des 7. Energieforschungsprogramms der Bundesregierung


Cold forming processes are considered highly efficient manufacturing processes in terms of material utilization and productivity. Complex lubricant systems are necessary for error-free and reliable production in cold forging. Established systems consisting of zinc phosphate and soap are often used. However, these are energetically and ecologically unfavorable when applied and cleaned. Single-layer lubricant systems, on the other hand, offer the possibility of ensuring environmentally friendly and energetically favorable production, provided that the application of the lubricants is adapted to the process. Relevant variables are, on the one hand, the application temperatures of the lubricants, which must be adapted to the occurring process temperatures. On the other hand, the required lubricant quantities depend on the loads and surface enlargements during forming. For the optimum and resource-saving design of single-layer lubricant systems, process monitoring of the relevant variables is essential. Conventionally, process monitoring, if available, has so far only taken place in the form of force and displacement sensors. These conventional sensors record the process events from a relatively large distance and do not allow a detailed assessment of the tribological system.

[1] Schematic illustration of lubricant and temperature monitoring in the multistage process


At the beginning of the project, the indicators are selected and integrated into the lubricant, and indicator standardization data sets are created for the subsequent measurements. For this purpose, the behaviour of the indicators must be calibrated as a function of the coating thickness and temperature. Test rigs and test methods are designed and implemented for the calibration. In parallel, process analytics will be set up and integrated into a sample process. The process analysis consists of a measuring cell in which the component surfaces are optically recorded and the subsequent software processing and provision of the measurement results. Tribometer tests are carried out to investigate the influence of the integrated indicators on the performance of the lubricants. The tribometer parameters to be used are derived from the sample process itself and from simulations of the sample process. Finally, the measurement technology is tested in an industrial environment.


The joint project InPUT – Inline Process Monitoring of Forming Processes by means of Tribological Systems (funding code: 03EN2038A) is funded by the Federal Ministry for Economic Affairs and Climate Action (BMWK) within the 7th Energy Research Program of the Federal Government. The PtU would like to thank the project sponsor, the Forschungszentrum Jülich GmbH and the project partners Schondelmaier GmbH Presswerk, CARL BECHEM GMBH and ISRA VISION AG.

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