How to Choose the Material For Creating Your Stack Prototype

Effective prototype motor laminations depend on selecting a material based on the motor’s exact performance characteristics. Heat, corrosion, magnetic fields, and external operating conditions are just some of the considerations bearing a significant impact on lamination materials. Cost and lead time also affect the production feasibility of certain metals.

Nickel, cobalt, and silicon steel are three of the most common materials for motor laminations. Learn more about each stack material below, including their pros and cons.

Nickel Alloys

Nickel alloys are a combination of iron and 49-80% pure nickel. At low-to-moderate induction, nickel has high permeability and low core losses. It also provides basic corrosion and moisture resistance, and coatings and heat treatments can further increase the nickel’s resistivity. The strip thickness of nickel alloys is between 0.004 and 0.020 inches. Compared to cobalt, nickel is less expensive, making it a more popular material for prototype motor lamination stacks.

Thomson Lamination Company (TLC) uses a variety of nickel alloys, including:

• HiPerm 49
• HyMu 80
• VDM MAG 50
• VDM MAG 7940
• Permenorm 5000 V5
• ULTRAVAC 80

Nickel Pros and Cons

• Pros: High permeability, low core losses, and reduced costs over cobalt.
• Cons: More expensive than silicon steel and requires a sophisticated annealing process. Because annealed nickel is quite fragile, your manufacturer must have a high degree of skill and experience.

Cobalt Alloys

Cobalt alloys contain iron, 48-50% cobalt, and a small percentage of vanadium. The saturation point of cobalt can reach up to 23 kG, which greatly reduces motor core/energy losses. More durable than nickel, cobalt is a good choice for high-performance motors, especially those with high flux densities requiring zero saturation.

TLC uses the following cobalt alloys in prototype motor laminations:

• Hiperco 50
• IMPHY AFK 502
• Vacodur 49

Like our nickel laminations, we can supply cobalt alloy laminations in thicknesses ranging between 0.004 and 0.020 inches.

Cobalt Pros and Cons

• Pros: High tensile strength and saturation point. Excellent resistance to abrasions, corrosion, and heat. Cobalt is ideal for low weight requirements and harsh environments where longevity is a concern.
• Cons: More expensive than most alternatives and requires a difficult annealing process. Even slight errors in annealing temperatures can permanently damage cobalt’s magnetic properties. Only a manufacturer with advanced technical knowledge and resources can consistently anneal cobalt without compromising its high-performance characteristics.

Silicon Steel

Silicon steel, also known as electrical steel, is best suited for strong electromagnetic fields. There is a wide variety of silicon steel grades and coating options suited for prototype motor laminations. Silicon steel is also an effective choice for:

• Generators
• Reactors
• Magnetic coils
• Transformers

The right silicon steel depends on the motor’s performance requirements and application. TLC most frequently works with standard silicon steel thicknesses between 0.014 and 0.025 inches. For specialized applications, we also work with thin-gauge silicon steel between 0.003 and 0.010 inches.

Silicon Steel Pros and Cons

• Pros: Silicon steel is versatile and better at building and sustaining magnetic fields than regular steel. Its magnetic properties also result in higher magnetic penetration and increased electrical resistance, with reduced hysteresis losses and core eddy current losses. Because of silicon steel’s wide availability in various grades and thicknesses, it is cost-effective and supports shorter lead times. Compared to nickel and cobalt, silicon steel reduces wear on stamping tools, resulting in greater output consistency and fewer tooling changeovers.
• Cons: Silicon steel is more brittle and susceptible to corrosion than other materials, potentially affecting the motor lamination’s longevity. Depending on the grade used and the intended application, parts made with this material sometimes require secondary processing.

Stack Prototyping Services From Thomson Lamination

The most common materials for prototype motor laminations are nickel, cobalt, and silicon steel. Each one has a wide range of alloy types and treatments that influence the final product’s strength, magnetic properties, corrosion resistance, and other properties.

Since motor lamination material often affects the motor’s surrounding components, choosing the most effective material bears a major impact on overall motor and system function. Each material option also determines how design engineers must stack, weld, or bond laminations, which can affect overall motor design.

Download our eBook, “Choosing the Right Material: Why Is Stack Prototyping Important?”, to learn more about prototype motor laminations. Contact Thomson Lamination or request a quote to get started with your unique solution.