Ring-shaped NdFeB permanent magnet

1. Product Overview

Ring-shaped NdFeB permanent magnets deliver exceptional magnetic performance and superior demagnetization resistance, with high-precision dimensional customization. Their unique annular design offers unparalleled flexibility for high-performance magnetic solutions in compact spaces. Compared to ferrite magnets, they provide equivalent magnetic field strength in smaller volumes, enabling lightweight device design. Additionally, they offer lower unit magnetic energy costs, ensuring significant long-term economic benefits.  

2. Technical Parameters

Product Name: Ring-shaped NdFeB Permanent Magnet  

Magnet Grade: N40 (Br ≥13.2 kGs, Hcj ≥10.8 kOe)  

Dimensions: OD 24mm × ID 12mm × H 2mm  

Dimensional Tolerances: OD±0.05mm, ID±0.05mm, H±0.05mm  

Operating Temperature: ≤80°C (High-temp versions customizable)  

Density ≥7.5 g/cm³  

Surface Magnetic Field: 2,900 Gs  

Flux Value: 2.9 mWb (Fluxmeter-tested)  

3. Manufacturing Process

Special-Shaped Cutting: Performed using dedicated non-standard wire-cutting equipment for non-square/non-circular geometric machining.

Grinding & Shaping: Used for complex structures and high-precision contour finishing to ensure dimensional and geometric tolerances.

Demagnetization Treatment: Initial demagnetization followed by precise magnetization to prevent magnetic deviation after assembly.

Laser Engraving & Marking: Marks the N-pole polarity and supports custom patterns or serial numbers as per customer requirements.

 4. Surface Treatment & Plating

To enhance corrosion resistance and aesthetics:  

Default Plating: Triple-layer Ni-Cu-Ni (customizable)  

Standard Thickness: Ni (3μm) + Cu (5μm) + Ni (4μm) (customizable)  

Optional Plating : Noble metals (Au/Ag) for conductivity / corrosion resistance  

Pre-treatment: Solvent degreasing/alkaline cleaning → Ensures coating adhesion

5. Appearance & Dimensional Inspection  

All products undergo strict quality control:  

- Manual inspection (micrometer/caliper)  

- Visual inspection (800-1,200 Lux illumination, 20-750px distance)  

- 2D optical measurement (for irregular geometries)  

- CCD automated sorting & full inspection (appearance/dimensions)  

- Flux testing (batch consistency verification)  

6. Reliability Testing  

6.1 Temperature Demagnetization Test:  

- 85°C/85%RH exposure for 2 hours (demagnetization ≤10%)  

6.2 Mechanical Testing:  

- Tensile/compression/ flexural tests → Validates structural integrity  

7. Packaging Process  

Magnetic-safe packaging protocol:  

1. Reject appearance/dimensional defects  

2. Uniform magnetization & alignment of conforming products  

3. Custom quantitation/labeling per box  

4. Vacuum sealing + magnetic shielding/buffer pads  

5. Master carton with moisture/collision/interference protection  

(Custom packaging available)

8. Application Fields: 

-Motors & Generators: BLDC motors, wind turbine generators, stepper motors  

- Electronics & Sensors: Magnetic sensors, speakers/earphones  

- Medical & Research: MRI systems  

- Emerging Technologies: Wireless charging, magnetic levitation systems  

9. Usage Precautions:

-Temperature: Never exceed Curie point (310-340°C) → Irreversible demagnetization  

- Mechanical: Avoid impacts/over-press fits (brittle material)  

- Polarity: Install according to orientation marks  

- Environment: Store away from humidity/heat/acids/alkalis  

- Safety: Keep >750px from pacemakers/HDDs/IC cards  

10. Customization & Services  

- Dimensions/shapes/coatings (layers, thickness, color)  

- Polarity/magnetic strength customization  

- Laser marking (logos/serial numbers)  

- Application-specific encapsulation & pull-force testing  

11. Company Introduction

Dongguan Jinkun New Materials Co., Ltd. focuses on R&D and manufacturing of high-performance magnetic materials. Guided by the principle of "Technology as the foundation, Quality as the soul," it aims to be a global leader in magnetic solutions. Its products are widely used in new energy, smart manufacturing, communications, and healthcare, earning strong trust from clients worldwide.

Request samples, datasheets (MSDS/RoHS), or certifications (ISO9001, IATF16949, etc.) from sales engineers.