Arc NdFeB Magnets

Description

Product Overview

Arc (tile) NdFeB magnets are the most critical component in surface permanent magnet (SPM) electric motors. Produced from sintered neodymium-iron-boron powder through isostatic pressing and vacuum sintering, they combine the highest energy density of any commercial permanent magnet material with tight dimensional tolerance for reliable motor assembly.

Ningbo Vanguard Technologies supplies arc magnets across the full grade family — from standard N-grade through M, H, SH, UH, and EH high-temperature series — enabling precise performance matching for each motor operating environment. All pieces undergo full magnetic testing, dimensional inspection, and salt-spray or HAST corrosion evaluation before shipment.

Whether you need a standard catalogue geometry or a fully custom arc profile, Vanguard can provide sample shipment within 10–15 days and mass-production support for rotor assembly or bare-magnet supply.

Quick View

Arc NdFeB Magnet Selection Snapshot

N35-N55

Available Energy Grade Range

From standard high-output grades to high-temperature motor grades.

80-200 °C

Typical Working Temperature

N, M, H, SH, UH and EH series can be matched to motor duty cycle.

10-15 Days

Prototype Sample Lead Time

Fast sampling after drawing, grade, coating and magnetization confirmation.

OEM / ODM

Custom Motor Magnet Support

Arc radius, angle, skew, chamfer, coating and matched-pole sets are available.

Temperature Grade Guide

N Series

80 °C

M Series

100 °C

H Series

120 °C

SH Series

150 °C

UH / EH

180-200 °C

Application Demand Focus

EV Traction

High Temp.

Servo Motor

Low Cogging

Wind PMG

Large Arc

Pump / HVAC

Coating

Robot Joint

Compact

1Drawing ReviewArc radius, angle, tolerance

2Grade MatchBr, Hcj, temperature margin

3Coating PlanNiCuNi, epoxy, Zn, custom

4MagnetizationRadial, parallel, multi-pole

5InspectionFlux, dimension, coating

Industries Served

Key Applications

EV Traction Motors

Drive motors for BEV/PHEV requiring SH/UH-grade arcs with ≥150 °C Tw for sustained high-speed operation.

Servo & Spindle Motors

High-pole-count surface-mount arcs for CNC spindles and industrial servo drives demanding ultra-low cogging.

Wind Generators

Large-format arc tiles for direct-drive PMG rotors; SH/UH grades handle outdoor thermal cycling.

Pump & Compressor

Hermetic BLDC pump motors for HVAC and refrigeration compressors; epoxy-coated for condensate resistance.

Robot Joint Motors

Compact high-torque arc magnets for humanoid robot and AGV joint actuators with tight dimensional tolerances.

Power Generation

Radial-flux generator rotors, marine propulsion and aerospace starter-generators requiring N52M peak energy.

Magnetic Performance

Grade & Magnetic Properties

Standard grades for arc motor magnets. All values at 20 °C. Values are typical; exact grade selection is confirmed per application.

Grade	Remanence		Coercivity		Intrinsic Coercivity		Max. Energy Product		Temp. Coefficient (α)		Max. Working Temperature °C (L/D=0.7)
	Br		Hcb		Hcj		(BH)max		αBr (%/°C)	αHcj (%/°C)
	T	kGs	kA/m	kOe	kA/m	kOe	kJ/m³	MGOe	αBr (%/°C)	αHcj (%/°C)
N30	1.08–1.13	10.8–11.3	≥798	≥10.0	≥955	≥12	223–247	28–31	−0.12	−0.76	80
N33	1.13–1.17	11.3–11.7	≥836	≥10.5	≥955	≥12	247–271	31–34	−0.12	−0.76	80
N35	1.17–1.22	11.7–12.2	≥868	≥10.9	≥955	≥12	263–287	33–36	−0.12	−0.76	80
N38	1.22–1.25	12.2–12.5	≥899	≥11.3	≥955	≥12	287–310	36–39	−0.12	−0.76	80
N40	1.25–1.28	12.5–12.8	≥907	≥11.4	≥955	≥12	302–326	38–41	−0.12	−0.76	80
N42	1.28–1.32	12.8–13.2	≥915	≥11.5	≥955	≥12	318–342	40–43	−0.12	−0.76	80
N45	1.32–1.38	13.2–13.8	≥923	≥11.6	≥955	≥12	342–366	43–46	−0.12	−0.76	80
N48	1.38–1.42	13.8–14.2	≥923	≥11.6	≥955	≥12	366–390	46–49	−0.12	−0.76	80
N50	1.40–1.45	14.0–14.5	≥796	≥10.0	≥876	≥11	382–406	48–51	−0.12	−0.76	80
N52	1.43–1.48	14.3–14.8	≥796	≥10.0	≥876	≥11	398–422	50–53	−0.12	−0.76	80
N55	1.46–1.52	14.6–15.2	≥796	≥10.0	≥876	≥11	414–430	52–54	−0.12	−0.76	80
N35M	1.17–1.22	11.7–12.2	≥868	≥10.9	≥1114	≥14	263–287	33–36	−0.12	−0.68	100
N38M	1.22–1.25	12.2–12.5	≥899	≥11.3	≥1114	≥14	287–310	36–39	−0.12	−0.68	100
N40M	1.25–1.28	12.5–12.8	≥923	≥11.6	≥1114	≥14	302–326	38–41	−0.12	−0.68	100
N42M	1.28–1.32	12.8–13.2	≥955	≥12.0	≥1114	≥14	318–342	40–43	−0.12	−0.68	100
N45M	1.32–1.38	13.2–13.8	≥995	≥12.5	≥1114	≥14	342–366	43–46	−0.12	−0.68	100
N48M	1.37–1.43	13.7–14.3	≥1027	≥12.9	≥1114	≥14	366–390	46–49	−0.12	−0.68	100
N50M	1.40–1.45	14.0–14.5	≥1033	≥13.0	≥1114	≥14	382–406	48–51	−0.12	−0.68	100
N52M	1.43–1.48	14.3–14.8	≥1050	≥13.2	≥1114	≥14	398–422	50–53	−0.12	−0.68	100
N54M	1.45–1.50	14.5–15.0	≥1051	≥13.2	≥1114	≥14	414–438	52–55	−0.12	−0.68	100
N35H	1.17–1.22	11.7–12.2	≥868	≥10.9	≥1353	≥17	263–287	33–36	−0.12	−0.66	120
N38H	1.22–1.25	12.2–12.5	≥899	≥11.3	≥1353	≥17	287–310	36–39	−0.12	−0.66	120
N40H	1.25–1.28	12.5–12.8	≥923	≥11.6	≥1353	≥17	302–326	38–41	−0.12	−0.66	120
N42H	1.28–1.32	12.8–13.2	≥955	≥12.0	≥1353	≥17	318–342	40–43	−0.12	−0.66	120
N45H	1.32–1.36	13.2–13.6	≥963	≥12.1	≥1353	≥17	342–366	43–46	−0.12	−0.66	120
N48H	1.37–1.43	13.7–14.3	≥995	≥12.5	≥1353	≥17	366–390	46–49	−0.12	−0.66	120
N50H	1.40–1.45	14.0–14.5	≥1011	≥12.7	≥1353	≥17	382–406	48–51	−0.12	−0.66	120
N52H	1.43–1.48	14.3–14.8	≥1027	≥12.9	≥1353	≥17	398–422	50–53	−0.12	−0.66	120
N35SH	1.17–1.22	11.7–12.2	≥876	≥11.0	≥1592	≥20	263–287	33–36	−0.11	−0.56	150
N38SH	1.22–1.25	12.2–12.5	≥907	≥11.4	≥1592	≥20	287–310	36–39	−0.11	−0.56	150
N40SH	1.25–1.28	12.5–12.8	≥939	≥11.8	≥1592	≥20	302–326	38–41	−0.11	−0.56	150
N42SH	1.28–1.32	12.8–13.2	≥987	≥12.4	≥1592	≥20	318–342	40–43	−0.11	−0.56	150
N45SH	1.32–1.38	13.2–13.8	≥1003	≥12.6	≥1592	≥20	342–366	43–46	−0.11	−0.56	150
N48SH	1.37–1.43	13.7–14.3	≥1027	≥12.9	≥1592	≥20	366–390	46–49	−0.11	−0.56	150
N50SH	1.40–1.45	14.0–14.5	≥1003	≥12.6	≥1592	≥20	382–406	48–51	−0.11	−0.56	150
N30UH	1.08–1.13	10.8–11.3	≥812	≥10.2	≥1990	≥25	223–247	28–31	−0.10	−0.50	180
N33UH	1.13–1.17	11.3–11.7	≥852	≥10.7	≥1990	≥25	247–271	31–34	−0.10	−0.50	180
N35UH	1.17–1.22	11.7–12.2	≥860	≥10.8	≥1990	≥25	263–287	33–36	−0.10	−0.50	180
N38UH	1.22–1.25	12.2–12.5	≥876	≥11.0	≥1990	≥25	287–310	36–39	−0.10	−0.50	180
N40UH	1.25–1.28	12.5–12.8	≥899	≥11.3	≥1990	≥25	302–326	38–41	−0.10	−0.50	180
N42UH	1.28–1.32	12.8–13.2	≥899	≥11.3	≥1990	≥25	318–342	40–43	−0.10	−0.50	180
N45UH	1.32–1.36	13.2–13.6	≥908	≥11.4	≥1990	≥25	342–366	43–46	−0.10	−0.50	180
N48UH	1.37–1.43	13.7–14.3	≥908	≥11.4	≥1990	≥25	366–390	46–49	−0.10	−0.50	180
N28EH	1.04–1.08	10.4–10.8	≥780	≥9.8	≥2388	≥30	207–231	26–29	−0.10	−0.45	200
N30EH	1.08–1.13	10.8–11.3	≥812	≥10.2	≥2388	≥30	223–247	28–31	−0.10	−0.45	200
N33EH	1.13–1.17	11.3–11.7	≥836	≥10.5	≥2388	≥30	247–271	31–34	−0.10	−0.45	200
N35EH	1.17–1.22	11.7–12.2	≥876	≥11.0	≥2388	≥30	263–287	33–36	−0.10	−0.45	200
N38EH	1.22–1.25	12.2–12.5	≥899	≥11.3	≥2388	≥30	287–310	36–39	−0.10	−0.45	200
N40EH	1.25–1.28	12.5–12.8	≥899	≥11.3	≥2388	≥30	302–326	38–41	−0.10	−0.45	200
N42EH	1.28–1.32	12.8–13.2	≥899	≥11.3	≥2388	≥30	318–342	40–43	−0.10	−0.45	200
N45EH	1.32–1.36	13.2–13.6	≥899	≥11.3	≥2388	≥30	342–366	43–46	−0.10	−0.45	200
N28AH	1.04–1.08	10.4–10.8	≥787	≥9.9	≥2786	≥35	207–231	26–29	−0.10	−0.45	230
N30AH	1.08–1.13	10.8–11.3	≥819	≥10.3	≥2786	≥35	223–247	28–31	−0.10	−0.45	230
N33AH	1.13–1.17	11.3–11.7	≥843	≥10.6	≥2786	≥35	247–271	31–34	−0.10	−0.45	230
N35AH	1.17–1.22	11.7–12.2	≥876	≥11.0	≥2786	≥35	263–287	33–36	−0.10	−0.45	230
N38AH	1.22–1.25	12.2–12.5	≥899	≥11.3	≥2786	≥35	287–310	36–39	−0.10	−0.45	230

Typical Physical Properties (All Sintered NdFeB Grades)

Parameter	Unit	Reference Value	Parameter	Unit	Reference Value
Curie Temperature	°C	310 ~ 400	Thermal Conductivity	W/m·°C	8 ~ 10
Density	g/cm³	7.4 ~ 7.7	Young's Modulus	GPa	150 ~ 200
Vickers Hardness	HV	500 ~ 700	Electrical Resistivity (C∥)	μΩ·m	1.4 ~ 1.6
Recoil Permeability	—	1.02 ~ 1.08	Electrical Resistivity (C⊥)	μΩ·m	1.2 ~ 1.4
Compressive Strength	MPa	1000 ~ 1100	Coeff. of Thermal Expansion (C∥)	10⁻⁶/°C	4 ~ 9
Flexural Strength	MPa	150 ~ 400	Coeff. of Thermal Expansion (C⊥)	10⁻⁶/°C	−2 ~ 0

Magnetization Orientations Available

Surface Treatment

Coating & Plating Options

NdFeB is susceptible to oxidation without adequate surface protection. Vanguard specifies and verifies the following coating systems per IEC 60068 and ASTM B117 salt-spray standards.

Ni·Cu·Ni Triple Layer

Industry standard for clean, low-humidity environments. Bright silver finish.

Dimension Capability

Arc magnets are defined by outer radius (R), inner radius (r), arc angle (θ), and axial length (L). Standard tolerance is ± 0.05 mm on all dimensions; tight-tolerance ± 0.03 mm available on request. Skewed and twisted configurations supported for cogging-torque reduction.

Dimension	Minimum	Maximum	Standard Tol.
Outer Radius (R)	5 mm	200 mm	± 0.05 mm
Inner Radius (r)	3 mm	195 mm	± 0.05 mm
Arc Angle (θ)	15°	180°	± 0.2°
Axial Length (L)	2 mm	150 mm	± 0.05 mm
Thickness (t = R–r)	2 mm	50 mm	± 0.05 mm

Engineering Selection

How to Specify Arc NdFeB Motor Magnets

A reliable arc magnet program starts with the motor duty cycle, not only the magnet grade. Vanguard reviews operating temperature, demagnetization risk, rotor speed, adhesive process, corrosion exposure, and assembly method before recommending the right material and coating system.

Thermal margin: Confirm winding hot-spot temperature, rotor temperature rise, overload duration, and cooling method. Higher Hcj grades improve resistance to irreversible flux loss in high-temperature or high-current conditions.

Magnetic circuit: Match Br, magnet thickness, pole arc coefficient, air gap, and back-iron saturation to the required torque constant, speed range, and efficiency target.

Mechanical fit: Define outer radius, inner radius, arc angle, axial length, chamfer, skew, and bonding clearance so each arc magnet seats accurately on the rotor surface.

Environment: Select NiCuNi, Zn, epoxy, or composite coating according to humidity, coolant exposure, salt-spray requirement, working temperature, and adhesive compatibility.

Custom Development

From Drawing to Mass Production

Stage	What We Check	Output
Design Review	Drawing, grade, coating, magnetization direction, tolerance stack-up and assembly method.	DFM feedback and confirmed quotation basis.
Tooling	Pressing mold, grinding fixture, inspection gauge and magnetizing fixture preparation.	Stable process plan for repeat production.
Sampling	Dimensions, magnetic data, coating thickness, surface condition and packing method.	Sample shipment with inspection report.
Mass Production	Batch consistency, lot traceability, final inspection and shipment release.	Approved production lots for motor assembly.

Quality Assurance

Inspection & Validation

Every production lot is controlled from raw material blending through sintering, machining, coating, magnetization, cleaning, and packing. Inspection plans can be aligned with customer drawings, AQL requirements, or PPAP-style documentation for automotive projects.

Magnetic testing: Br, Hcb, Hcj, (BH)max, surface flux, flux linkage, and magnetization direction verification.

Dimensional control: Radius, angle, length, thickness, parallelism, chamfer, and appearance checked by calibrated gauges.

Coating verification: Thickness, adhesion, porosity, salt spray, humidity, and thermal shock testing according to coating type.

Traceability: Lot number, furnace batch, inspection report, RoHS/REACH declaration, and packing label records.

Request a Quote

Information Needed for Fast Quotation

To speed up engineering review, please send a 2D/3D drawing or the key dimensions below. If the motor is still in design stage, Vanguard can also help compare grade, coating, and magnetization options before tooling.

Material grade or target Br/Hcj, plus maximum working temperature
Outer radius, inner radius, arc angle, axial length, chamfer, and tolerance
Magnetization direction, number of poles, and required surface flux if available
Coating type, salt-spray requirement, adhesive process, and operating environment
Sample quantity, annual volume, packing requirement, and target delivery schedule

Support

Frequently Asked Questions

How do I choose between M, H, SH, and UH grades for my motor?

Grade selection depends on the maximum winding temperature your motor will experience. M-grade (≤100 °C) suits most industrial servo applications; H-grade (≤120 °C) is standard for EV auxiliary motors; SH (≤150 °C) and UH (≤180 °C) are specified for EV traction drives and high-ambient industrial use. We recommend providing your thermal simulation data so we can confirm the correct grade.

What is the minimum order quantity for custom arc magnets?

For custom geometry, samples can be arranged from as few as 50–200 pieces. Mass-production MOQ is typically 1000–10000 pieces per specification, though this is flexible depending on magnet size and grade. Contact us to discuss your project volume.

Can you supply arc magnets already assembled into a rotor?

Yes. Vanguard provides integrated rotor assembly services — including magnet bonding, balancing, and shaft press-fitting — as part of our Magnetic Systems product line. We can supply bare arc magnets or complete rotor sub-assemblies depending on your manufacturing flow.

Do you provide material certifications and test reports?

Full material certificates (chemical composition, magnetic test data, coating thickness, salt-spray results) are provided with each shipment as standard. ROHS, REACH, and conflict-mineral declarations are available on request.

What is the lead time for arc NdFeB magnets?

Prototype samples: 10–15 working days. Mass-production orders: 25–35 working days depending on grade, coating, and quantity. Rush sampling may be available — please inquire.

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Arc NdFeB Magnets

Description

Arc NdFeB Magnets

Arc NdFeB Magnet Selection Snapshot

Key Applications

Grade & Magnetic Properties

Coating & Plating Options

Dimension Capability

How to Specify Arc NdFeB Motor Magnets

From Drawing to Mass Production

Inspection & Validation

Information Needed for Fast Quotation

Frequently Asked Questions

Get in Touch with Us

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