Tribological Control in Adaptive Die Systems for Cold Forging: Investigation of Tribological Influence on Ejection Force Reduction

10 pages•Published: August 6, 2026

Christian Siedbürger, Christoph Kuhn and Peter Groche

Abstract

In cold forging, ejection forces are a key indicator of the tribological state and tool wear, as they are largely governed by the clamping pressure resulting from elastic die springback after the main forming stroke. This study investigates how an adaptive extrusion die reduces the external pressure, thereby lowering the clamping pressure and positively affecting ejection forces. A two-step model has been developed in a tribometer to represent the ejection stage. This test reproduces the tribological preloading from the main forming operation, as well as the reversal of motion under varying contact pressure. The findings from this test are transferred to the real process by finite element simulations. The results reveal a pressure-depending friction trend for polymer-based single layer lubricants in the reverse stroke, such that reducing contact pressure is accompanied by a decrease in the friction coefficient. Consequently, the beneficial effect of the adaptive die on ejection forces is not only caused by reduced clamping pressure but is further amplified by a reduction in friction. This indicates that adaptive tooling systems can contribute effectively to increased tool life.

Keyphrases: adaptive die systems, ejection forces, polymer based lubricants, tribology

In: Numpon Mahayotsanun (editor). Proceedings of The 11th International Conference on Tribology in Manufacturing Processes & Advanced Surface Engineering, vol 4, pages 65-74.

Links:	https://easychair.org/publications/paper/hhWC
	https://doi.org/10.29007/qgt9

BibTeX entry

@inproceedings{ICTMP2026:Tribological_Control_Adaptive_Die,
  author    = {Christian Siedbürger and Christoph Kuhn and Peter Groche},
  title     = {Tribological Control in Adaptive Die Systems for Cold Forging: Investigation of Tribological Influence on Ejection Force Reduction},
  booktitle = {Proceedings of The 11th International Conference on Tribology in Manufacturing Processes & Advanced Surface Engineering},
  editor    = {Numpon Mahayotsanun},
  series    = {EPiC Series in Technology},
  volume    = {4},
  publisher = {EasyChair},
  bibsource = {EasyChair, https://easychair.org},
  issn      = {2516-2322},
  url       = {/publications/paper/hhWC},
  doi       = {10.29007/qgt9},
  pages     = {65-74},
  year      = {2026}}

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