Comprehensive Guide for Permanent Magnet Selection

Choosing the Right Magnet for Your Application

Selecting the correct magnet for your application can be complex due to the variety of materials and performance factors involved. This guide simplifies the selection process by outlining key considerations and differences between the strongest rare earth magnets—Neodymium (NdFeB) and Samarium Cobalt (SmCo)—to help engineers and manufacturers make informed decisions.

Key Factors for Magnet Selection

When specifying a magnet for your application, consider these critical parameters:

• Operating Temperature – What temperatures will the magnet be exposed to?
• Environmental Conditions – Will the magnet be in contact with steel, aluminum, plastic, or corrosive elements?
• Dimensional Constraints – What size and tolerance requirements must be met?
• Integration – Is the magnet part of an assembly, or will it function independently?
• Coating Requirements – Will environmental factors like humidity, chemicals, or moisture require additional protection?

Addressing these questions early helps narrow down material choices and ensures long-term reliability.

Comparing Neodymium and Samarium Cobalt Magnets

Magnet Strength (BHmax)

• Neodymium (NdFeB): Offers the highest energy density, with BHmax ranging from 30 MGOe to 55 MGOe.
• Common grades: N35, N38, N40, N42, N45, N48, N50, N52, and N55.
• Samarium Cobalt (SmCo): Lower maximum energy product (BHmax from 16 MGOe to 32 MGOe) but provides better thermal and corrosion resistance.
• Common grades: 16, 18, 20, 22, 24, 26, 28, 30, and 32.

Neodymium is the stronger option, but SmCo performs better in high-temperature environments.

Temperature Stability & Coercivity (Hci)

Magnet stability is critical, especially in high-heat or demagnetization-prone environments. Coercivity (Hci) determines how well a magnet resists external demagnetizing forces:

Selecting the appropriate coercivity ensures your magnet maintains performance under expected operating conditions.

Optimizing Magnet Performance

Strength vs. Application Needs

The highest-strength magnet isn't always the best option. For example, sensor applications may require precise field strengths, where an overly powerful magnet could disrupt performance.

Cost Considerations

Higher grades and increased coercivity drive up material costs.

• Example: N48H is more expensive than N48, and N48SH costs even more.
  Balancing performance and budget is key.

Coatings for Protection

The right coating enhances durability based on environmental exposure:

• Nickel (Ni-Cu-Ni): General-purpose protection
• Epoxy: Best for humid or chemical-heavy environments
• Gold: Used in specialized applications like medical devices
  Understanding exposure conditions helps in selecting the correct finish.

Explore Our Coated Magnet Selection

Size and Shape Constraints

Magnet performance is affected by physical dimensions. Smaller or thinner magnets may require higher coercivity to maintain strength and resist demagnetization.

Making the Right Choice

Magnet selection involves trade-offs between strength, temperature resistance, and cost.  If your application requires high-temperature stability,  SmCo or a high-coercivity NdFeB magnet may be the best choice. If maximum strength is the priority,  Neodymium provides the highest performance.

For expert guidance on selecting the right magnet for your specific application, contact our team—we’re here to help optimize your design. If you're looking for a custom magnet size or coating that is not available on our website, please fill out our RFQ form and our experts will reach back out shortly.