What Is N40?
N40 is the sweet spot for designers who want higher flux than N38 without the tighter temperature headroom or cost of N42 and above. It is widely used in voice-coil motors, compact servo motors, and magnetic couplings for low-temperature duty.
N40 Technical Specifications
| Remanence (Br) | 12.6–12.9 kGs (1.26–1.29 T) |
| Coercive Force (HcB) | ≥11.6 kOe (≥923 kA/m) |
| Intrinsic Coercivity (HcJ) | ≥12 kOe (≥955 kA/m) |
| Energy Product (BHmax) | 38–41 MGOe (303–326 kJ/m³) |
| Max Operating Temperature | 80°C |
| Temperature Coefficient (Br) | -0.12 %/°C |
| Temperature Coefficient (HcJ) | -0.60 %/°C |
| Density (typical) | 7.5 g/cm³ |
| Vickers Hardness (typical) | 550–650 HV |
Values per IEC 60404-5 / GB/T 13560. Actual production values fall within the range quoted; batch-specific BH-curve data is provided on every certificate of conformance.
Where N40 Is Used
N40 is specified across the following application categories. Each links to a full application brief with design requirements and recommended grade combinations.
Recommended Coatings for N40
Coating choice is driven by operating environment and assembly method. For N40, the typical options are:
- •NiCuNi
- •Epoxy over NiCuNi
See our NdFeB Coatings Guide for a full comparison with salt spray data and decision framework.
Design Considerations When Specifying N40
- 01Avoid for applications near 80°C — specify N40H instead to preserve magnetic integrity under thermal cycling.
- 02Best in sealed indoor assemblies where coating wear and humidity are not concerns.
- 03Consider GBD-processed N40H as a near-cost alternative when even modest temperature margin is needed.
Related Grades
Frequently Asked Questions
What is N40 NdFeB magnet?
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N40 is the sweet spot for designers who want higher flux than N38 without the tighter temperature headroom or cost of N42 and above. It is widely used in voice-coil motors, compact servo motors, and magnetic couplings for low-temperature duty.
What is the maximum operating temperature of N40?
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N40 sintered NdFeB is rated for continuous operation up to 80°C. This is the practical upper limit before thermal demagnetization begins to affect performance. For a safety margin, design for a working temperature at least 20–30°C below the maximum rating.
What is the BHmax of N40?
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N40 delivers an energy product (BHmax) in the range of 38–41 MGOe (303–326 kJ/m³). This is the maximum magnetic energy density the grade can produce, measured according to standard IEC 60404-5 magnetic testing.
What applications use N40 magnets?
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N40 is typically specified for Industrial Automation. The grade's combination of 38–41 MGOe (303–326 kJ/m³) energy product and 80°C maximum service temperature determines its fit for any given motor or actuator design.
Request a Quote for N40 Magnets
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