Product Descriptions
For motor designers seeking a balance between high magnetic output and cost control, the N45 arc segment magnet is an optimal choice. With a typical energy product of 42‑45 MGOe and remanence of 1.33‑1.37 T, N45 provides strong flux density while being more machinable and less brittle than ultra‑high grades like N52. This makes it ideal for mass‑produced BLDC motors, PM synchronous motors, servo motors, and automotive auxiliary drives where consistent performance and cost‑effectiveness are paramount. Our N45 arc segments are produced from 100% virgin neodymium‑iron‑boron (purity ≥95%, no recycled scrap) in a fully integrated IATF 16949‑certified facility. We precision grind inner radius (R1), outer radius (R2), chord height, and thickness to tolerances as tight as ±0.03 mm, ensuring a uniform air gap and minimal cogging torque. Standard arc angles include 60°, 72°, 90°, and 120°, with custom angles available. For elevated temperature applications, we offer N45H (120°C), N45SH (150°C), and N45UH (180°C) grades with dysprosium addition. Ni‑Cu‑Ni triple plating (13‑18 μm) is standard, with epoxy or Parylene coating for electrical insulation. Each batch is 100% flux tested and supplied with a material test certificate and dimensional report.
Why N45 Arc Magnets Excel in Motor Applications
Optimal Energy/Cost Ratio
N45 delivers approximately 20‑25% more flux than N35, but at a lower cost than N48 or N52. For medium‑duty motors, it provides the required torque without over‑specifying materials, reducing rotor assembly costs.
High‑Temperature Grades Available
Standard N45 operates to 80°C. For EV cooling fans or under‑hood actuators, choose N45SH (150°C) or N45UH (180°C). Our heavy rare‑earth addition ensures coercivity stability under thermal stress.
Consistent Arc Geometry
Our rotary grinding fixtures hold arc radius tolerance within ±0.02 mm and chord height ±0.03 mm. Segments from the same batch fit interchangeably on the rotor core, reducing assembly time.
Technical Specifications – N45 Arc Segment Magnets
Below are magnetic properties and common segment geometries for N45 arc segment magnets. Custom dimensions, angles, and grades are available based on your motor design.
| Grade | Br (T) | Hcj (kA/m) | BHmax (kJ/m³) | Max Temp (°C) | Typical Use |
|---|---|---|---|---|---|
| N45 (standard) | 1.33-1.37 | ≥955 (≥12 kOe) | 342-358 (43-45 MGOe) | 80 (176°F) | General BLDC motors, fans, pumps |
| N45H (high temp) | 1.32-1.36 | ≥1350 (≥17 kOe) | 334-350 (42-44 MGOe) | 120 (248°F) | EV auxiliary drives, actuators |
| N45SH (super high temp) | 1.30-1.34 | ≥1590 (≥20 kOe) | 326-342 (41-43 MGOe) | 150 (302°F) | Servo motors, industrial robots |
| N45UH (ultra high temp) | 1.28-1.32 | ≥1990 (≥25 kOe) | 310-334 (39-42 MGOe) | 180 (356°F) | EV traction motors (secondary) |
*Standard arc angles: 60°, 72°, 90°, 120°. Custom angles from 30° to 150° available. Inner radius from 15 mm to 200 mm; thickness 3‑20 mm; length 10‑200 mm.
Magnetic direction
Coating / Plating
Neodymium permanent arc magnets primarily consist of neodymium, iron, and boron. The iron content makes them susceptible to oxidation when exposed to atmospheric conditions. To ensure long-term durability, all our high-strength magnets receive micron-thin protective coatings that preserve both magnetic properties and adhesive performance. Multiple surface treatment options are available, with triple-layer nickel plating (Ni-Cu-Ni) being the most prevalent. Additional coatings include zinc, copper, epoxy, gold, silver, passivation treatments, and PVC encapsulation for specialized applications.
High-Precision Manufacturing
With precision grinding and cutting, tolerances of +/-0.05mm can be achieved during the manufacturing process.
Magnetic Grade Parameters
Quality Assurance – Full Process Control
Our vertically integrated factory ensures consistent quality for every N45 arc segment magnet. The process begins with vacuum induction melting of virgin rare earths (neodymium, iron, boron) plus dysprosium/terbium for high‑temp grades. After jet milling to 3‑5 μm powder, the material is pressed in a segmented die under a magnetic field to achieve radial or parallel orientation as specified. Sintering and multi‑stage heat treatment optimize the microstructure for maximum coercivity. Segments are then ground on all critical surfaces using dedicated CNC rotary grinders, with in‑process gauging. Ni‑Cu‑Ni plating is applied in automated barrel lines with real‑time XRF thickness monitoring. Final inspection includes 100% magnetic flux measurement (Helmholtz coil), dimensional check (CMM or vision system), and coating adhesion cross‑cut test. Salt‑spray samples are run per ASTM B117. All shipments include full test certificates with material traceability. We are IATF 16949 and ISO 9001 certified, ensuring compliance with automotive and industrial OEM requirements.
Packaging & Logistics – Ready for Production Lines
Each arc segment is placed in a dedicated foam pocket within anti‑static trays to prevent edge chipping. Trays are stacked and packed into reinforced export cartons. Lead times: standard segments 10‑12 days; custom tooling 15‑20 days after drawing approval. Free samples available for qualified projects. We support just‑in‑time delivery and consignment stock for high‑volume OEMs.
FAQ
Q: What does the N45 grade mean for an arc segment magnet, and what is its typical maximum energy product?
A:N45 indicates sintered NdFeB with a maximum energy product (BH)max of 43–47 MGOe, roughly 342–374 kJ/m³. It offers high remanence (1.32–1.38 T) but moderate coercivity (Hcj ≥ 12 kOe). It is not suitable for temperatures above 80°C without de-rating.
Q:Why is an N45 arc segment magnet prone to corrosion, and what coatings are recommended?
A: N45 contains >30 wt% neodymium and iron, which oxidizes rapidly in humid air. Standard coatings: NiCuNi (5–15 µm) for moderate humidity, epoxy (20–30 µm) for salt spray, or Zn for low cost. Edge coverage matters because arcs have sharp corners.
Q: How does the arc angle of an N45 segment affect its magnetic flux distribution?
A: A wider arc angle (e.g., 120°) increases total flux but reduces peak flux density at the air gap due to self-demagnetization. Optimal arc for N45 is 90°–110° for DC motors. Too narrow (60°) wastes magnet material as leakage flux increases.
Q: Can N45 arc segment magnets be used in a sensorless BLDC motor?
A: Yes, but N45's high remanence creates strong back-EMF, easy for zero-crossing detection. However, temperature rise must be kept below 80°C; otherwise flux drops irreversibly. Use a Hall sensor if ambient exceeds 60°C.
Q: How do you magnetize an N45 arc segment magnet – radial or parallel?
A: Most N45 arc segments are parallel magnetized (flux lines straight through the arc thickness). Radial magnetization requires special tooling and reduces yield. Parallel is cheaper and gives a flatter air-gap flux profile, suitable for most PMDC and BLDC motors.
Q: What applications are suitable?
A: Electric motors, magnetic couplings, robotics, renewable energy systems, medical devices, and industrial machinery.
Q: How do you ensure quality?
A: Our products undergo strict quality control, and we provide test documentation. We hold certifications like ISO9001, IATF16949, RoHS, and REACH.