NdFeB vs. SmCo: How to Choose the Right Magnet for Your Application
The Short Answer
Choose NdFeB when you need maximum magnetic strength at room temperature and cost is a factor.
Choose SmCo when your application operates above 150°C, demands long-term stability, or operates in corrosive environments without coating options.
Head-to-Head Comparison
| Property | NdFeB | SmCo |
|---|---|---|
| Max Energy Product | 28–55 MGOe | 16–32 MGOe |
| Remanence (Br) | 10,800–14,800 G | 8,200–11,500 G |
| Coercivity (Hcj) | ≥955 kA/m | ≥630 kA/m |
| Max Operating Temp | 80–200°C (grade dependent) | 250–350°C |
| Temp Coeff of Br | -0.12%/°C | -0.03 to -0.05%/°C |
| Corrosion Resistance | Poor (requires coating) | Excellent (no coating needed) |
| Brittleness | High | Very High |
| Relative Cost | 1× (baseline) | 3–8× |
The Temperature Factor
This is the single most important differentiator. NdFeB loses magnetic strength rapidly as temperature increases. A standard N42 NdFeB magnet operating at 150°C may lose 20–30% of its room-temperature performance — and may suffer irreversible demagnetization if the operating point crosses the knee of the demagnetization curve.
SmCo, by contrast, has a reversible temperature coefficient roughly 3× better than NdFeB. A Sm2Co17 magnet at 250°C retains approximately 85% of its room-temperature flux — predictably and reversibly.
When to Choose NdFeB
- EV motors and generators (operating below 150°C with cooling)
- Consumer electronics — speakers, headphones, phone vibration motors
- Magnetic separators and holding applications
- Any application where maximum flux density is the primary requirement
- Cost-sensitive applications at moderate temperatures
When to Choose SmCo
- Aerospace actuators and sensors (operating 200–350°C)
- Downhole oil & gas tools (high temperature + pressure)
- Military and defense applications (reliability-critical)
- Applications where coating is impractical or undesirable
- Precision instruments requiring long-term magnetic stability
The Cost Question
SmCo is typically 3–8× more expensive than NdFeB on a per-kg basis. But the total cost comparison depends on your application:
- If NdFeB requires active cooling to operate within its temperature range, the system cost may exceed SmCo.
- If NdFeB requires expensive coating (Parylene, for example) for corrosion protection, the gap narrows.
- If a design can be downsized using SmCo's better temperature stability, the magnet volume reduction may offset the higher per-kg cost.
Our Recommendation
Tell us about your application — operating temperature, space constraints, performance requirements and budget. Our magnetic engineering team will recommend the optimal material and grade, backed by thermal analysis and demagnetization curve modeling.