Manufacturing Influences on Wedge-Pins: A Comparative Study of Bending Characteristics for Direct Cooled Hairpin Windings

Preitschaft A, Zürrlein T, Stauber S, Hahn R, Ihne T, Franke J, Risch F (2026)

Publication Type: Conference contribution

Publication year: 2026

Original Authors: Anja Preitschaft, Tobias Zürrlein, Simon Stauber, Roman Hahn, Thorsten Ihne, Jörg Franke, Florian Risch

Event location: Funchal

DOI: 10.1109/ICEM68283.2026.11757097

Abstract

To meet the increasing demand for high power density in electric traction motors, innovative cooling concepts such as direct cooling of hairpin windings are becoming essential. This paper investigates the wedge-pin technology, a novel approach for direct cooling using expandable slot liners, from the perspectives of production engineering and manufacturing feasibility. Although conventional flat wires are well characterized in automated process chains, the manufacturing behavior of wedge-shaped conductors remains largely unexplored. The study focuses on the mechanical and electrical integrity of wedge-pins during the forming process. A comparative experimental analysis is conducted between wedge-shaped and conventional rectangular conductors using 2D swing bending, a key process step in sequential tool-bound bending. A central challenge is the springback effect, which is influenced by the conductor's geometry and material flow. This paper evaluates the impact of cold deformation on electrical properties and quantifies the springback behavior compared to flat-wire benchmarks. Within the scope of this study, the results demonstrate that wedge-pins maintain high electrical integrity. Initial experimental data show an increase of approximately 0.05 % in measured ohmic resistance, which appears more stable across bending angles than that of conventional hairpins. Additionally, the springback behavior of wedge-pins is nearly identical to the automotive standard. This confirms that the wedge-pin technology can be integrated into existing production lines without specialized tool modifications. These findings provide proof of concept for wedge-pins as a manufacturing-friendly solution that combines superior thermal performance with process robustness, though further validation is required to confirm these trends for mass production.

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How to cite

APA:

Preitschaft, A., Zürrlein, T., Stauber, S., Hahn, R., Ihne, T., Franke, J., & Risch, F. (2026). Manufacturing Influences on Wedge-Pins: A Comparative Study of Bending Characteristics for Direct Cooled Hairpin Windings. In Proceedings of the 2026 International Conference on Electrical Machines (ICEM). Funchal , PT.

MLA:

Preitschaft, Anja, et al. "Manufacturing Influences on Wedge-Pins: A Comparative Study of Bending Characteristics for Direct Cooled Hairpin Windings." Proceedings of the 2026 International Conference on Electrical Machines (ICEM), Funchal 2026.

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