Aperam announced the development of a new production method for electric vehicle (EV) traction motor stators and rotors based on an in-plane helical winding process, referred to as the “slinky” method. The approach enables single-piece stator and rotor components to be formed from continuous strips of iron-cobalt alloy across a wide range of diameters, addressing key efficiency and packaging constraints in EV powertrains.
While in-plane helical winding is established in the electrical steel industry, Aperam has adapted the process for iron-cobalt alloys, which offer high magnetic performance but are traditionally difficult to form.
The method combines linear stamping with controlled in-plane bending, enabling precision forming while reducing material waste compared with conventional stacked lamination techniques.
The process is enabled by Aperam’s AFK family of iron-cobalt alloys, including AFK1, AFK18, and AFK502R. These materials are characterized by high saturation induction and are used in applications requiring high magnetic performance. Ongoing materials development has improved their mechanical properties, allowing forming techniques that were previously impractical and supporting scalable production of complex motor geometries.
Applied to electric motor designs, the combination of AFK alloys and the slinky process supports increased power density, higher torque output, and reduced motor size. These attributes are relevant for electric vehicle powertrains, electric aviation platforms such as eVTOL aircraft, and other electrified propulsion systems where efficiency, weight, and packaging are critical constraints.
Compared with conventional stamping methods, which can result in high material scrap, the slinky process forms components from continuous strip material, improving material utilization and supporting more efficient electric motor manufacturing.
Production of slinky-formed motor components is supported by Aperam Alloys & Specialties’ facilities in Imphy and Amilly, France. The Amilly site is equipped for industrial-scale production of precision-formed motor components for electrified mobility and advanced propulsion applications.
The development forms part of Aperam’s broader work in high-performance materials and manufacturing processes supporting electrification across automotive, aerospace, and mobility sectors.
Filed Under: Electric Motor, Technology News