High-Strength Hiperco® with Low Core Loss: Meeting the Demands of High-Speed Motor Design

The challenge of high-speed electric motor design: choosing between electrical efficiency and mechanical strength. New high strength with low cores loss motor stacks, Hiperco® Prime and Hiperco® Prime Plus eliminate this compromise with dual materials from a single strip, one optimized for stators with 30% lower core loss, another for rotors with >400 MPa yield strength.

The Result: 2-5% higher continuous power and 100°F lower operating temperatures.

The electrification revolution continues accelerating across industries, from aerospace to automotive, and from defense to industrial applications. As designers push the boundaries of what's possible with electric motors, a fundamental materials challenge has emerged: the need for stator and rotor stacks that can deliver exceptional electrical efficiency and the mechanical strength required for high-speed and high-torque operation.

The Materials Challenge in Power Dense Motor Design

Traditional electric motor design has forced engineers to make difficult trade-offs. They could choose materials with excellent motor design for high power density motors to maximize efficiency, but with insufficient mechanical strength for high-speed rotors. Alternatively, they could opt for materials with adequate yield strength but compromised efficiency. This compromise directly impacts power output, operational temperatures, and ultimately, the performance envelope of the entire system.

This compromise has become increasingly untenable for applications where every percentage of efficiency and every gram of weight matters. The movement toward high power density motors has created a critical need for high-strength soft magnetic materials, specifically those with yield strength exceeding 400 MPa for rotor stack components.

Understanding Hiperco® Technology

Carpenter Electrification's Hiperco® family represents the gold standard for high-induction soft magnetic alloys. These iron-cobalt alloys consistently deliver approximately 25% higher torque density and 25% higher power density for motors and generators compared to silicon steel alternatives.

However, even industry-leading materials face limitations: Grades that deliver very low core loss typically cannot provide the >400 MPa yield strength required for rotor integrity. This limitation can constrain the potential of next-generation power dense motor designs.

Read More: Choosing the Right Alloy: Comparing Magnetic Materials for Electric Motors

Prime and Prime Plus: Two Specialized Grades from One Material

Recent advances have led to the development of two specialized products. Hiperco® Prime and Hiperco® Prime Plus, created from the same strip material through a proprietary manufacturing process. This cutting-edge technology tailors the material's properties to specific application requirements.

• Hiperco Prime Plus - Stator-Optimized Stacks: These stacks deliver approximately 30% lower core loss compared to stators produced with standard Hiperco®. The reduced loss translates directly to increased power density and significantly cooler operating temperatures, critical advantages for maintaining system reliability and extending component life.

• Hiperco Prime - Rotor-Optimized Stacks: These complementary stacks provide yield strength exceeding 400 MPa and up to 500 MPa, delivering the mechanical robustness essential for reliable high-speed operation. This enables motors to operate at higher rotational speeds and higher torque, extracting more power from the same form factor.

Both stator and rotor stacks maintain Hiperco®'s signature high induction properties, ensuring that designers don't sacrifice the fundamental magnetic advantages that have made these materials indispensable in high-performance solutions.

Measurable Performance Advantages

The performance benefits of High-Strength Hiperco® grades are quantifiable and significant:

• 2-5% higher continuous motor power — extracting more output from the same motor size
  
  
• Approximately 30% lower core loss — significantly improving motor efficiency
  
  
• 100°F lower motor operational temperature — enhancing reliability and extending component life
  
  
• Enhanced mechanical strength for high torque and high rotational speeds — enabling operation in previously unattainable performance regimes

These advantages translate to real-world benefits across diverse applications:

• Aerospace and eVTOL: Higher power density means increased passenger capacity and extended flight range without adding battery weight, critical factors in the emerging urban air mobility market.

• Defense Systems: Significantly lower operating temperatures enhance reliability in mission-critical applications where failure is not an option, while reduced weight and volume create cascading benefits throughout the platform.

• Medical Systems: Surgical robots and surgical power tools incorporate miniaturized motors that often operate at very high rotational speeds.

Read More: How Your Industry Can Benefit From Rotor and Stator Stacks

Proprietary Advanced Processing Methodology

The key to this breakthrough lies in the proprietary processing and stack level testing used to manufacture and certify Hiperco Prime and Hiperco Prime Plus. This innovative manufacturing approach creates two specialized grades from the same material, each optimized for its specific role within the electromagnetic system.

By precisely controlling the thermal and mechanical properties during processing, the lamination stacks can be tailored to maximize yield strength or minimize core losses, depending on the application requirements.

This dual-grade approach ensures perfect compatibility between stator and rotor components while eliminating the traditional compromise between mechanical strength, core loss, and efficiency. The ability to produce variations from the same material streamlines supply chains and ensures consistent quality from a single source.

Our unique finished stack testing methodology ensures stators and rotors perform as designed, a significant advancement from ASTM loose ring testing standard in the industry. 

Implementation Considerations

The implementation of High-Strength Hiperco® grades requires thoughtful design consideration to realize their full potential:

• For Stator Applications — The low-loss grade maximizes efficiency in stator stacks, reducing waste heat and enabling more compact designs with enhanced cooling requirements. This is particularly valuable in applications where thermal management is a critical design constraint.
  
  
• For Rotor Applications — The high-strength grade maintains mechanical integrity at elevated speeds and under high loads, enabling reliable operation in power dense motor designs that extract maximum performance from the system. This is especially important for aerospace and defense applications where rotational speeds moving to higher frequency designs can exceed 20,000 RPM.

Read More: The Carpenter Electrification Difference in High Performance Solutions

Technical Expertise and Support

Hiperco® Prime and Hiperco Prime Plus stacks are the result of over 80 years of specialized expertise in soft magnetics. These innovative stators and rotors represent more than just raw materials; they offer comprehensive solutions from concept to scale-up. Our technical experts are available to provide guidance and support at every stage of the process, ensuring successful implementation and optimal performance.

The vertical integration in production ensures consistent quality from melt to final product, with advanced vacuum induction melting capacity, state-of-the-art processing equipment and novel stack testing capabilities - supporting these materials' development and production.

Looking Ahead 

Hiperco® Prime and Hiperco® Prime Plus rotor stacks represent a significant milestone in the evolution of electric motor design. By eliminating the traditional compromise between electrical efficiency and mechanical strength, these materials enable the next generation of high-performance motors and generators.