Neodymium Magnets for EV Motors

For motors operating at 150°C, N42SH or N45SH grades are the standard choice — both offer Hcj ≥ 1592 kA/m and Tmax of 150°C. For motors reaching 180°C, N48UH is preferred. For extreme applications at 200°C — common in high-performance axial flux or heavy commercial truck motors — N45EH is specified. Operating temperature is the primary selection criterion. Contact Mainrich's application engineers to confirm the right grade for your specific thermal profile before ordering tooling.

Interior permanent magnet (IPM) motor rotors use arc-shaped magnets embedded in slots within the rotor lamination stack. The arc geometry matches the rotor slot profile exactly, maximizing magnet fill factor and minimizing flux leakage at the slot edges. This directly improves motor efficiency and power density. Block magnets are used in surface-mount (SPM) and axial flux motor designs where rotor geometry is fundamentally different.

Mainrich operates under MIIT-licensed supply agreements for Dy and Tb, and has been export-license-ready since the 2025 rare-earth control framework came into force. For every OEM order, we prepare country-of-origin certificates, conflict-mineral declarations, and export license documentation within 5 business days of request. Our Grain Boundary Diffusion process also materially reduces heavy rare-earth intensity in SH / UH / EH grades, which lowers exposure to future export-control shocks. For EV programs sensitive to supply-chain risk, we can also stage safety stock against a signed 12-month forecast.

Minimum order quantity starts at 10 pieces per specification — suitable for prototype and engineering validation phases. Sample lead time is 10–15 business days. Mass production lead time is 30–45 business days depending on grade and volume. We recommend ordering samples first to validate dimensions and magnetic performance before committing to full production tooling.

Yes. GBD is applied on all Mainrich SH, UH, and EH grades as a standard process — not a premium option. Typical heavy rare-earth loading after GBD: N42SH / N45SH at 1.5–2.5 wt% Dy+Tb, N48UH at 3–5 wt%, and N45EH at 5–7 wt%. Against conventional sintered NdFeB of the same coercivity class, GBD reduces Dy+Tb consumption by up to 70%, directly lowering both bill-of-material cost and exposure to heavy rare-earth supply volatility. Magnetic performance — Br, Hcj, knee-point temperature — is maintained or improved. Demagnetization curves at operating temperature are available per grade on request.

Yes. Block-laminated NdFeB with epoxy insulation layers ≤ 30 μm is available for rotors operating at high inverter switching frequencies where eddy-current losses become significant. Typical configurations: 4–12 segments per pole. Depending on geometry and frequency, segmented magnets reduce rotor magnet losses by 40–70% versus monolithic blocks, improving continuous torque and reducing rotor heating. Send your operating frequency, pole geometry, and magnet dimensions for a DFM proposal within 24 hours.

Arc magnet dimensions are controlled through precision CNC grinding and cutting, with in-process measurement using dedicated gauges and periodic verification on coordinate measuring machines (CMM). Statistical Process Control (SPC) is applied to all critical dimensions with Cpk targets of ≥ 1.33. Full dimensional inspection reports are provided per production batch. For critical OEM qualification programs, 100% dimensional screening is available on request.

For most EV motor applications, NiCuNi (triple-layer nickel) coating provides sufficient protection — it withstands 96 hours of neutral salt spray testing per ISO 9227. For motors exposed to coolant fluids or high-humidity thermal cycling environments, NiCuNi + Epoxy overcoat is recommended, offering 500+ hours salt spray resistance. Zinc coating is also available where NiCuNi is not compatible with assembly adhesive systems. Refer to ECHA REACH guidelines for chemical resistance requirements in EU-market vehicle applications.