Achieving Liftoff with High-Performance Stator and Rotor Stacks

pilot screen of electric aircraft

Aircraft manufacturers have relied on Carpenter Technology materials and expertise since the Wright Brothers took flight in 1903. As our aerospace customers advanced, so did we, developing trailblazing alloys to meet more and more extreme performance requirements. 

Our materials can be found in mission-critical flight applications around the globe and out of this world, from commercial jets to the Perseverance Mars Rover.

The latest challenge to solve has been engineering materials for power-dense, lightweight, and efficient motors for electric and hybrid aircraft. Electric airplanes and air taxis — also known as electric vertical take-off and landing aircraft (eVTOLs) — represent an emerging sector that is essential for reducing man-made climate effects, backed by investors, and advanced by innovative companies who are flight testing models right now.

The technical demands of building electric motors for aircraft are intense: enough power and torque for take-off and landing, but light enough to ensure efficient flight. Every watt and ounce counts.

High-Performance Soft Magnetic Alloys

Carpenter Technology’s advanced iron-cobalt soft magnetic alloys, such as Hiperco 50, deliver the higher power and torque density required to make electric motors lighter and smaller. Power density improvements of up to 30 percent have been achieved, opening the door for e-motor designers to create motors that are up to:

  • 30 percent smaller
  • 25 percent higher torque
  • 3 percent more efficient

To serve customers from design to prototyping to production and realize improved motor responses using these high-performance alloys, Carpenter Electrification expanded this expertise into the production of stator and rotor stacks at our Motor Technology Center in Reading, Pennsylvania. This provides capability to process high volume strip feedstock through high performance Hiperco stacks at a single stie. 

Stacks Engineered for Electric Aircraft Motors

The same iron-cobalt alloy characteristics that deliver high magnetic performance also present challenges when producing stacks. Improper processing can compromise rotor and stator performance by as much as 50 percent. Carpenter Electrification engineers have a deep understanding of metallurgical structure-magnetic property relationships and have developed processes to isolate and eliminate harmful variables. Their alloys and stacking methods for low growth, high strength, and tailored properties support the most demanding motor design requirements and production tolerances — resulting in superior motor responses.

The Motor Technology Center helps electric aircraft and eVTOL motor specialists bring their new technology to life with:

  • Metallurgical and stack design expertise
  • best-in-class soft magnetic alloys
  • Cutting-edge lamination, heat treatment, bonding, and assembly processes
  • Prototyping, quality testing, and certification
  • Low rate initial production (LRIP)

Full-scale production of iron-cobalt stator and rotor stacks is the next logical step.

Scaling Up for Market Adoption

Carpenter Electrification is building the first manufacturing facility capable of producing Hiperco-based stacks at volume. The state-of-the-art Stack Production Center picks up where the Motor Technology Center ends, adding full-scale stack production to our in-house capabilities.

The Stack Production Center automates steps in the production process while maintaining the same stringent quality controls used to certify materials used in aircraft engines. Beyond meeting the volume demands of our customers, the new facility provides them with process efficiencies and a reliable supply chain of world-class stator and rotor stacks.

Carpenter Electrification now provides a complete ecosystem for high-performance electric motor stacks: design, testing, prototyping, iteration, qualification, LRIP, and high-volume manufacturing.

Electric aircraft and eVTOLs will change the way people move through the world. We’re excited to help electric motor innovators bring these new technologies to market and to scale.

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