How to Choose Material for Lamination Stack Prototyping

Motor laminations, or lam stacks, are thin sheets of metal that are stacked on top of one another and bonded together for use in rotors, transformers, and more. This stacking process allows for less eddy current loss when compared to using a solid piece of metal.

There are a variety of materials that can be used to make lamination stacks, and the best options for you depend upon the type of motor and its performance requirements. At Thomson Lamination Company, we have years of experience in stack lamination prototyping as well as high-volume production, and we’re known for our tight tolerances, experience with a large number of materials, and the knowledgeable, friendly service that helps you make the right decisions for your project.

Cobalt Alloys

Cobalt alloys are made of 48-50% cobalt with iron and a small amount of vanadium. At TLC, we offer Hiperco 50 and Vacodur 49 for motor laminations, which can range in thickness from 0.004 to 0.020 inches. Cobalt is a fantastic choice for high-performance applications that require high flux densities and no saturation.

  • Pros: Cobalt offers high tensile strength, saturation as high as 23 kG, and excellent resistance to corrosion, heat, and wear and tear for a long-lasting solution in harsh environments. It’s ideal for weight-sensitive applications.
  • Cons: Cobalt requires a specialized annealing process after stamping, and improper annealing temperatures can damage the magnetic properties of the alloy—a mistake that cannot be corrected, which is why the annealing process should be completed by an experienced team. Cobalt is also more expensive than many other material options.

Nickel Alloys

Depending upon the application, nickel alloys may contain 80% pure nickel or 49% pure nickel with iron. TLC works with HiPerm 49, Permenorm 5000 V5, HyMu 80, VDM MAG 50, ULTRAVAC 80, and VDM MAG 7940 in thicknesses of 0.004 to 0.020 inches. Nickel alloys are commonly used for motor components because they offer low core losses with high permeability at low to moderate inductions.

  • Pros: Nickel is less expensive than cobalt, and it offers high permeability and low core losses.
  • Cons: Nickel is more expensive than silicon steel, and the annealing process requires special considerations. Annealed nickel is fragile, so it’s important that the manufacturer is skilled and experienced with using nickel for motor lamination prototypes.

Silicon Steel (Electrical Steel)

Silicon steel, also known as electrical steel, is ideal for use in electrical applications, including magnetic coils, generators, reactors, transformers, and anywhere electromagnetic fields must be considered. TLC works with thin-gauge electrical steel, including Sura and Arnon, as well as silicon steel grades M15, M19, M22, M27, M36, and M45. Silicon steel can be stamped at thicknesses of 0.014 to 0.025 inches, while thin-gauge electrical steel thicknesses range from 0.003 to 0.010 inches.

  • Pros: By adding silicon to steel, you can increase the lifespan of stamping tools and dies, increase the electrical resistance of the component, reduce hysteresis loss, and allow greater magnetic penetration. In short, silicon steel can build and maintain magnetic fields more efficiently than regular steel. It resists corrosion and reduces core eddy current losses. Because it’s available in so many grades and thicknesses, it’s a cost-efficient and versatile material that can meet the needs of varied applications.
  • Cons: Silicon steel parts may need additional processing, depending upon the type of silicon steel and its intended use, which can add time and cost to your manufacturing process. It does not do well for long periods in shelf storage and will rust in humid environments.

Your Trusted Source for Lamination Stack Prototyping

With nearly six decades of experience and a 76,000-square-foot facility with a variety of top-of-the-line high-speed presses and post-stamping capabilities, Thomson Lamination Company provides custom motor lamination prototyping and full-scale fabrication services. From precise tolerances to special annealing considerations, our designers, engineers, and technicians can accommodate nearly any request for specialized solutions in a variety of industries, including aerospace, automotive, military, medical, energy, and more. Contact us to learn more about lamination stack prototyping, available lam stack materials, and how TLC can meet or exceed your specifications and standards for quality, safety, and performance.