Selecting the optimal magnet for electric motors directly impacts efficiency (up to 98% in premium designs), manufacturing costs (magnets account for 25-50% of motor material costs), and operational lifespan. With industries like EVs and industrial automation demanding higher power density, understanding these four magnetic properties is essential for engineers and designers.

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1. Remanence (Br): The Power Driver

Remanence (Br) measures residual magnetic flux density after magnetization, expressed in Tesla (T). Higher Br values enable:

• Compact designs: A 1.4T NdFeB magnet produces 40% more flux than a 0.4T ferrite magnet, reducing motor size.

• Higher torque: EV motors using N52-grade NdFeB (Br=1.48T) achieve 15% faster acceleration vs. ferrite alternatives.
  Trade-off: High-Br materials like neodymium are sensitive to demagnetization at >150°C.
  

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2. Energy Product (BHmax): Efficiency Multiplier

The energy product (kJ/m³ or MGOe) defines stored magnetic energy. Compare common materials:

• Ferrite (3–5 MGOe): Low-cost but requires 5x more volume than NdFeB.

• NdFeB (35–52 MGOe): Enables 90% weight reduction in drone motors.

• Samarium Cobalt (25–32 MGOe): Ideal for aerospace (stable at 300°C).

Case Study: A 10kW industrial pump motor switched from ferrite to NdFeB, cutting magnet weight from 4.2kg to 0.8kg while maintaining output.

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