Hairpin stator from up close Copyright: © PEM RWTH Aachen University

The chair "Production Engineering of E-Mobility Components" (PEM) of RWTH Aachen University and the company "Röscher GmbH Automatisierungstechnik- und Konstruktion" from Berlin team up in the research project "anfaHair". The project, which is part of the Central Innovation Program for small and medium-sized enterprises (ZIM), is funded by the German Federal Ministry for Economic Affairs and Energy and is intended to help make the production of new types of electric motors more efficient.

Against high reject rates and low plant efficiency

To this end, PEM and its industrial partner are devoting themselves to the production area of so-called hairpin stators as the component of electric motors that is crucial to their performance and efficiency. The hairpin design with its plug-in coil structure made of solid copper wires is increasingly displacing conventional wire winding techniques. In the corresponding process chain, the main focus is on laser contacting of numerous copper ends. However, welding defects in series production currently still lead to high reject rates and low system efficiency. The research partners therefore want to counteract such strong interactions between preparatory processes and the actual welding process.

Decoupling processes and introducing a new method

The "anfaHair" project aims at decoupling the two processes of geometric weld seam preparation and subsequent contacting as well as developing a pre-fixing, "initially strong" and precise joining process. The procedure will then be integrated into the hairpin process chain, where it should enable reproducible and dimensionally stable alignment of the copper wires prior to welding and thus increase both the quality and the stability of the overall process chain.

The project with a total volume of around 500,000 euros will run until January 31st, 2023. Further information is provided in this press release.

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The project

  • "anfaHair": Initial strength joining in hairpin technology

Research objectives

  • Increase of process stability and quality by geometrically exact weld seam preparation
  • Reduction of process complexity through initially fixed pre-fixation of the hairpin ends (substitution of alignment and clamping processes)
  • Shifting of interface complexity to fixture construction

Research and project partners

PEM of RWTH Aachen University
Röscher GmbH


  • 02/01/2021 through 01/31/2023
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Project sponsor

AiF (ZIM cooperation project)

Funding code

  • KK 5057502PK0


Federal Ministry for Economic Affairs and Climate Action (BMWK)