01 / Overview
Application Overview
Permanent-magnet traction motors use NdFeB where the magnetic design needs high energy density within a restricted rotor volume. Magnet mass and temperature depend on the motor, cooling and duty cycle. Electrically excited and induction motors use other rotor designs; a vehicle brand or power rating does not identify a magnet specification.
02 / Material
Why NdFeB for EV Motors
NdFeB has high room-temperature energy product. Its usefulness in a traction motor depends on the field it delivers at the operating point, the available rotor volume and resistance to demagnetization. Ferrite and other motor architectures need a separate system comparison.
03 / Specifications
Key Design Requirements
Magnet temperature
Use a rotor temperature map covering continuous operation, transients and faults. Temperature class alone cannot establish grade suitability.
Intrinsic coercivity (HcJ)
Evaluate hot demagnetization curves against local opposing fields, including short-circuit and stall conditions. The listed SH minimum of 20 kOe is a room-temperature reference, not a hot motor requirement.
Flux consistency
Agree the measured quantity, fixture, temperature and acceptance range. A surface-field reading alone does not establish motor-to-motor torque variation.
Dimensional tolerance
Set critical dimensions from the rotor stack-up, air gap and retention design. Confirm the proposed production route can hold each feature.
Qualification records
Agree the customer’s quality-system, material declaration and batch inspection requirements with the proposed production site. Confirm export classification for the actual material and transaction.
04 / Grade Selection
NdFeB grade references for EV Motors
These educational references do not establish supply or thermal suitability. Review the actual hot curves, load line, opposing field and duty cycle before selecting a grade.
N42SH
150°C class · Super High Temperature (SH)N42SH reference: 40–43 MGOe at 20°C, with a nominal 150°C temperature class.
Reference; drawing review required
N45SH
150°C class · Super High Temperature (SH)N45SH reference: 43–46 MGOe at 20°C, with a nominal 150°C temperature class.
Reference; drawing review required
N48SH
150°C class · Super High Temperature (SH)N48SH reference: 45–48 MGOe at 20°C, with a nominal 150°C temperature class.
Reference; drawing review required
N42UH
180°C class · Ultra High Temperature (UH)N42UH reference: 40–43 MGOe at 20°C, with a nominal 180°C temperature class.
Reference; drawing review required
N45UH
180°C class · Ultra High Temperature (UH)N45UH reference: 43–46 MGOe at 20°C, with a nominal 180°C temperature class.
Reference; drawing review required
N42EH
200°C class · Extreme High Temperature (EH)N42EH reference: 40–43 MGOe at 20°C, with a nominal 200°C temperature class.
Reference; drawing review required
05 / Geometry
Typical Magnet Configurations
- Surface-mounted arc segments with a specified retention system
- Radial multipole rings for designs that accept the required orientation and pole pattern
- Skewed or Halbach arrangements evaluated in the complete motor
- Block magnets in V, spoke or other interior-PM cavities
Typical dimensions
Arc or block dimensions follow the rotor drawing. Radial rings have a separate documented size window; see the radial-ring reference.
06 / Engineering Notes
Design & Procurement Considerations
- 01A documented N45H specimen processed with a stated 0.35% Tb surface treatment reached 26.55 kOe HcJ from 17.67 kOe, about 50% higher. Br was 13.62 before and 13.61 kGs after treatment. This result does not establish a Dy saving or another grade’s performance.
- 02Qualify the coating and adhesive together for temperature, coolant exposure, cure and retention loads.
- 03Thermal and magnetic analysis must include realistic transient duty and local hot spots.
- 04Agree the actual material curves and inspection records before approving a production source.
07 / Resources
Further Reading
Market Update
China Rare Earth Export Controls: Item Classification and MOFCOM Licensing
Review the actual magnet or assembly, composition, exporter, parties and end use. A grade name does not determine the licensing outcome.
Buyer's Guide
Qualifying an NdFeB Supplier for Automotive and Robotics
Agree the quality and technical evidence for the programme, then verify the actual manufacturing and export route.
Technical
Grain Boundary Diffusion: Magnetic Results and Part Qualification
A reported N45H magnetic comparison and a separate historical Dy-reduction example support different conclusions.
08 / Compare
Related Engineering Comparisons
Comparison
N42 vs N42SH
Compare N42 and N42SH at 20°C, then assess the actual material at the intended operating point.
Comparison
NiCuNi vs Epoxy
NiCuNi is a metal plating stack; epoxy is a polymer coating that may be applied over a specified base layer.
Comparison
Factory Direct vs Trading Company
Compare the contracting route, access to production records and responsibility for the order.
FAQ / Questions
Frequently Asked Questions
What NdFeB grade is used in EV traction motors?
+
SH, UH and other coercivity classes are reference starting points. No class is a universal traction-motor minimum. Use the motor’s hot load line, fault fields and required output to qualify the material; Mainrich confirms grade and geometry against the drawing.
How much NdFeB does an EV motor use?
+
Use the named motor’s bill of materials. Magnet mass depends on topology, speed, cooling and output requirements; there is no single mass-per-kilowatt rule for an EV drivetrain.
Can GBD reduce heavy rare earth use in motor magnets?
+
GBD can concentrate diffusion material near grain boundaries and grain surfaces. The saving depends on the alloy, treated surfaces and acceptance limits. Mainrich’s N45H coercivity example and the separate 50H composition example cannot be combined into one test result.
Do high-temperature NdFeB grades require dysprosium or terbium?
+
A coercivity suffix specifies a performance class, not an alloy recipe. Chemistry and processing vary. Obtain a composition declaration and the actual hot curves; neither the suffix nor a low-HREE label establishes export clearance.
Start an RFQ
Request a Quote for EV Motors
Share your application, target dimensions, operating temperature, and annual volume. We respond within 1 business day. Grade, production route and inspection requirements are confirmed before a part-specific supply promise.