10 Things to Consider When Buying Permanent Magnets Company

Magnet Buyers Guide

Introduction

Magnets are essential components in various industries, including manufacturing, electronics, healthcare, and more. This guide will help you understand the different types of magnets, their properties, applications, and what to consider when purchasing them.

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Types of Magnets

1. Permanent Magnets
   • Neodymium (NdFeB) Magnets
     • Properties: Strongest type of permanent magnet, high resistance to demagnetization, brittle, and prone to corrosion.
     • Applications: Motors, hard disk drives, headphones, MRI machines.
   • Samarium Cobalt (SmCo) Magnets
     • Properties: High temperature stability, corrosion-resistant, brittle.
     • Applications: Aerospace, military, high-performance motors.
   • Alnico Magnets
     • Properties: High temperature stability, less powerful than NdFeB and SmCo, excellent corrosion resistance.
     • Applications: Sensors, electric guitar pickups, microphones.
   • Ceramic (Ferrite) Magnets
     • Properties: Economical, good resistance to demagnetization, brittle.
     • Applications: Loudspeakers, magnetic separators, refrigerator magnets.
2. Electromagnets
   • Properties: Magnetic field created by electric current, adjustable strength, requires power source.
   • Applications: Transformers, relays, magnetic lifting devices.
3. Temporary Magnets
   • Properties: Only exhibit magnetic properties when in the presence of a magnetic field.
   • Applications: Not commonly used in industrial applications.

Key Considerations When Buying Magnets

1. Magnetic Strength
   • Measured in terms of maximum energy product (MGOe). Higher values indicate stronger magnets.
   • Choose based on application requirements.
2. Temperature Stability
   • Some magnets can lose their magnetic properties at high temperatures.
   • Consider the operating temperature of your application.
3. Size and Shape
   • Magnets come in various shapes (disc, ring, block, etc.) and sizes.
   • Select based on the space constraints and design requirements of your application.
4. Coating and Material
   • Coatings (nickel, epoxy, gold) protect against corrosion.
   • Material choice depends on the environment (e.g., moisture, chemicals).
5. Cost
   • Permanent magnets vary in cost, with NdFeB being the most expensive.
   • Balance cost with performance requirements.
6. Supplier Reliability
   • Ensure the supplier is reputable and provides quality certifications.
   • Look for consistent supply chains, especially for critical applications.

Applications and Industry-Specific Requirements

1. Manufacturing
   • Motors and Generators: High strength, temperature stability.
   • Assembly Lines: Electromagnets for lifting and sorting.
2. Electronics
   • Speakers and Headphones: NdFeB magnets for high performance.
   • Hard Drives: Precise, small-sized magnets with strong fields.
3. Healthcare
   • MRI Machines: Strong, stable magnets like NdFeB or SmCo.
   • Medical Devices: Biocompatible coatings, corrosion resistance.
4. Automotive
   • Electric Vehicles: High performance and efficiency, usually NdFeB.
   • Sensors: Temperature stable, reliable performance.

Purchasing Tips

1. Bulk Purchasing
   • Consider bulk buying for cost savings if your application requires a large number of magnets.
2. Custom Magnets
   • Some suppliers offer custom shapes and sizes to fit specific applications.
3. Quality Assurance
   • Request samples and quality certifications.
   • Ensure the magnets meet industry standards.

Conclusion

Selecting the right magnet requires understanding your specific application needs and the properties of different types of magnets. This guide should provide a solid foundation for making informed purchasing decisions. Always consider the strength, stability, size, coating, and reliability of the supplier to ensure you get the best magnet for your requirements.

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): BHmax ranges from 16 MGOe to 32 MGOe, with 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.

Coercivity Grade Max Operating Temperature M Up to 100°C H Up to 120°C SH Up to 150°C UH Up to 180°C EH Up to 200°C TH Up to 220°C

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.

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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.

Optimize your design with the right magnet. Download our Magnet Selection Checklist for engineers.

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 want to learn more, please visit our website Permanent Magnets Company.