Sintered NdFeB Magnet
烧结钕铁硼（NdFeB）磁体
Sintered NdFeB (Neodymium–Iron–Boron) is the strongest commercial permanent magnet material available today. Through a powder-metallurgy sintering process it achieves the highest remanence and energy product of any magnet family — packing more field into a smaller volume than ferrite, alnico, or SmCo.
AIC Engineering supplies sintered NdFeB in grades from N35 up to N52, including low-temperature-coefficient (M/H/SH/UH/EH/AH) series for traction motors and sensors that must operate from −40 °C to +220 °C. Shapes include discs, blocks, rings, arcs, and custom-machined profiles with tolerances down to ±0.05 mm.
Every batch is processed in-house: alloy design → jet milling → field pressing → vacuum sintering → machining → coating → magnetizing → 100% flux inspection, ensuring consistent magnetic, dimensional, and corrosion-performance across volume deliveries.
Key Features
Highest Energy Product
Up to (BH)max 422 kJ/m³ (N52) — strongest field per unit volume of any commercial magnet.
Full Grade Range
N35–N52 plus M / H / SH / UH / EH / AH high-temperature series for EV and industrial use.
Custom Shapes & Tolerances
Discs, blocks, rings, arcs, cylinders and machined profiles — tolerance down to ±0.05 mm.
Corrosion-Resistant Coatings
Ni-Cu-Ni, Zn, epoxy, Au, electrophoresis and passivation coatings for harsh environments.
Magnetic Grades
Typical values at room temperature, sourced from the AIC Sintered NdFeB performance data sheet. Representative subset shown — full N30–N54 / 30M–52M / 30H–52H / 30SH–48SH / 28UH–45UH / 28EH–40EH / 28AH–35AH series available on request.
| Grade | Remanence Br (T) | Coercivity Hcb (kA/m) | Intrinsic Hcj (kA/m) | (BH)max (kJ/m³) | Max Op. Temp. Tw (°C) |
|---|---|---|---|---|---|
| N35 | 1.18–1.23 | ≥ 868 | ≥ 955 | 263–287 | ≤ 80 |
| N42 | 1.29–1.33 | ≥ 915 | ≥ 955 | 318–342 | ≤ 80 |
| N48 | 1.37–1.41 | ≥ 836 | ≥ 876 | 358–390 | ≤ 80 |
| N52 | 1.43–1.48 | ≥ 836 | ≥ 876 | 390–422 | ≤ 80 |
| 35M | 1.18–1.23 | ≥ 868 | ≥ 1114 | 271–287 | ≤ 100 |
| 42M | 1.29–1.33 | ≥ 955 | ≥ 1114 | 318–342 | ≤ 100 |
| 35H | 1.18–1.23 | ≥ 868 | ≥ 1353 | 263–287 | ≤ 120 |
| 42H | 1.29–1.33 | ≥ 955 | ≥ 1353 | 318–342 | ≤ 120 |
| 35SH | 1.18–1.23 | ≥ 876 | ≥ 1592 | 263–287 | ≤ 150 |
| 42SH | 1.29–1.33 | ≥ 987 | ≥ 1592 | 318–342 | ≤ 150 |
| 38UH | 1.23–1.26 | ≥ 899 | ≥ 1989 | 287–311 | ≤ 180 |
| 35EH | 1.17–1.23 | ≥ 836 | ≥ 2388 | 263–287 | ≤ 200 |
| 35AH | 1.17–1.23 | ≥ 860 | ≥ 2625 | 263–287 | ≤ 230 |
Powder-Metallurgy Process
From alloy design to magnetized, inspected parts — every step controlled in-house for batch consistency.
- Alloy design (Nd/Dy/Fe/B + Ti/Zr grain refiner)
- Vacuum induction melting & strip casting
- Hydrogen decrepitation (HD)
- Jet milling to 3–5 μm powder
- Die or rubber-mould pressing in alignment field ≥1.5 T
- Vacuum sintering (1050–1100 °C)
- Two-stage tempering (600 °C / 500 °C)
- Annealed blank inspection
- Wire / EDM / surface grinding to ±0.05 mm
- Blast cleaning & passivation
- Ni-Cu-Ni / Zn / epoxy / Au / e-coating
- SST corrosion test (24–720 h)
- Pulse magnetizing to design direction
- 100% flux / B-H measurement
- Dimensional & visual inspection
- Packaging with magnetizing-safe spacing
Magnetization Directions
Magnetization direction is set during pressing and finalized by the pulse-magnetizing coil. Standard directions for sintered NdFeB shapes:
Axial
Through thickness — most common for discs, blocks, and rings.
Diametrical
Across the diameter — used for rings and arcs in multipole assemblies.
Radial
Outward / inward through the ring wall — ideal for sensor and motor rotors.
Multipole
N/S pole pairs distributed around O.D. or end face — for encoders and BLDC rotors.
Coating Options
Sintered NdFeB is intrinsically corrosion-prone — surface treatment is mandatory for nearly all applications.
Ni-Cu-Ni
Triple-layer nickel — standard, 24–72 h SST, smooth bright finish.
Zn
Economical sacrificial coating for indoor / dry applications, 12–48 h SST.
Epoxy
Excellent humidity & salt-spray resistance, 240–720 h SST — marine & automotive.
Electrophoresis
Uniform thin coating on complex shapes — 240 h+ SST.
Au
Gold over nickel for medical and high-end electronics, biocompatible.
Passivation
Thin phosphate / chromate pre-coat for short-term protection prior to use.
Typical Applications
Special Form Features
Helical Tile
Arc segments with spiral joint geometry for smooth multipole rings and low cogging.
Tapered Tile
Conical wedge segments for axial-flux and tapered-rotor motor assemblies.
Custom Profiles
Irregular wedges, blocks, and capsules from mm-scale to large-format tiles.
Flexible Coating
Ni-Cu-Ni, Zn, Cr, Au, electrophoresis and other finishes for corrosion protection.
Special-shaped Magnets
Three main special-form categories — all available with custom dimensions, coatings, and magnetization.
螺旋瓦磁铁
Helical Tile Magnet
Spiral-jointed arc segments assemble into seamless multipole rings with minimal cogging torque.
- Coating
- Ni-Cu-Ni, Zn, Cr, Au, electrophoresis, etc.
- Dimensions
- Min 1 × 0.5 × 0.2 mm · Max 240 × 240 × 45 mm
- Magnetization
- Optional
锥度瓦磁铁
Tapered Tile Magnet
Conical wedge segments build axial-flux rotors and tapered ring assemblies.
- Coating
- Ni-Cu-Ni, Zn, Cr, Au, electrophoresis, etc.
- Dimensions
- Min 1 × 0.5 × 0.2 mm · Max 240 × 240 × 45 mm
- Magnetization
- Optional
异形磁铁
Irregular-shaped Magnet
Triangles, capsules, blocks and arcs — any profile machined from your drawing.
- Surface Coating
- Ni-Cu-Ni, Zn, Cr, Au, electrophoresis, etc.
- Dimensions
- Custom / optional
- Magnetization Direction
- Optional
Special Form Applications
Need a Custom NdFeB Magnet?
Send us your drawing or sample — our engineers will confirm grade, dimension, coating, magnetization direction, and high-temperature stability for your application. Samples and DFM support available.
Discuss Custom RequirementsProduct Manual
Sintered NdFeB Magnet Product Manualsintered-ndfeb-magnet.pdfDownload PDFFrequently Asked Questions
Answers to common questions about our magnets, customisation, ordering and shipping.
- What is the strongest grade of sintered NdFeB magnet you supply? +
- AIC Engineering supplies sintered NdFeB from N35 up to N52, the strongest commercial permanent magnet grade, with maximum energy product (BHmax) up to 422 kJ/m³ and remanence up to 1.48 T.
- What is the maximum operating temperature of sintered NdFeB magnets? +
- Standard grades operate up to 80 °C; high-temperature grades (N series with H/Sh/UH/EH suffixes) are stable up to 200 °C. Select the grade by your working temperature to avoid irreversible demagnetisation.
- Which coatings are available for NdFeB magnets? +
- Ni-Cu-Ni (nickel), Zn (zinc), Epoxy, and Gold coatings are available. NdFeB is prone to corrosion, so a coating matched to the environment (humidity, salt spray, acid) is required.