What are NdFeB disc magnets and where are they used?

Conclusion: NdFeB disc magnets are powerful neodymium-iron-boron permanent magnets in a flat, cylindrical (disc) shape, offering the highest energy product among commercial magnets — up to 52 MGOe — enabling compact yet strong magnetic fields. They are widely used in motors, sensors, speakers, holding assemblies, and medical devices. Neodymium NdFeB Disc Magnets are sintered rare-earth magnets known for exceptional magnetic strength relative to size. A typical N45 disc magnet (10mm diameter x 5mm thickness) can hold over 8 kg of ferrous material. Their disc geometry provides a uniform magnetic field across the flat faces, making them ideal for applications requiring concentrated flux. For demanding environments, a high temperature neodymium disc magnet (grades such as SH, UH, EH) maintains performance up to 200°C. As a custom neodymium disc magnet manufacturer, Ningbo Tujin Magnetic Industry produces precision disc magnets with tight tolerances and various coatings to meet specific application needs.

What Are NdFeB Disc Magnets? Composition & Key Properties

NdFeB (Neodymium-Iron-Boron) disc magnets are manufactured through a powder metallurgy sintering process. The alloy consists of Neodymium (Nd) for magnetic anisotropy, Iron (Fe) for high saturation magnetization, and Boron (B) to stabilize the tetragonal crystalline structure. Disc magnets are magnetized through the thickness (axial) or across the diameter (diametral), depending on the application. Key magnetic properties include:

• Remanence (Br): 1.17 - 1.48 Tesla (depending on grade)
• Coercivity (Hcj): 860 - 2,200 kA/m (higher for high-temperature grades)
• Maximum Energy Product (BHmax): 30 - 52 MGOe (239 - 414 kJ/m³)
• Curie Temperature: 310°C - 340°C (base composition)

Grades & Temperature Ratings: Selecting the Right Disc Magnet

NdFeB disc magnets are categorized by operating temperature and maximum energy product. The most common suffix codes indicate intrinsic coercivity and maximum working temperature. The table below summarizes standard grades for high temperature neodymium disc magnet selection.

For applications exceeding 120°C, a high temperature neodymium disc magnet with SH, UH, or EH grade is required to prevent irreversible demagnetization. Advanced coatings such as Ni-Cu-Ni (standard), epoxy, or passivation layers protect against corrosion.

Coatings for Disc Magnets

• Nickel-Copper-Nickel (Ni-Cu-Ni): Excellent corrosion resistance, suitable for most indoor/outdoor use.
• Epoxy: Provides electrical insulation and enhanced salt spray resistance.
• Gold or Zinc: Specialized for medical or decorative applications.

Major Applications of NdFeB Disc Magnets

Due to their high energy density, disc magnets are found in numerous industrial, commercial, and consumer products. Below are the primary sectors utilizing these magnets.

1. Electric Motors & Drives

Disc-shaped NdFeB magnets are used in BLDC motors, servo motors, stepper motors, and traction motors for electric vehicles (EVs). Their flat geometry allows efficient mounting on rotor surfaces. For new energy vehicles, high-temperature grades (SH/EH) ensure stable torque output at high operating temperatures.

2. Sensors & Magnetic Assemblies

Hall effect sensors, speed sensors, and position encoders often incorporate a small disc magnet as the field source. The uniform axial field simplifies sensor calibration. Disc magnets also serve as magnetic actuators in reed switches and proximity sensors.

3. Loudspeakers & Audio Equipment

High-end speakers, headphones, and microphones use NdFeB disc magnets for their compact size and strong magnetic flux, enabling better power handling and reduced distortion. A typical tweeter magnet might be an N42 disc of 20mm diameter.

4. Holding & Lifting Assemblies

Magnetic sweepers, magnetic clamps, and workholding devices utilize disc magnets in arrays. Their high pull force relative to weight makes them ideal for portable magnetic tools.

5. Medical Devices

Dental implant motors, MRI-compatible positioning systems, and magnetic therapy devices rely on precisely magnetized disc magnets with biocompatible coatings (e.g., gold or parylene).

Custom NdFeB Disc Magnets: Precision & Flexibility

As a custom neodymium disc magnet manufacturer, Ningbo Tujin offers tailored solutions for specific dimensional, magnetic, and coating requirements. Typical custom parameters include:

• Diameter range: 2mm to 120mm (or larger by arrangement)
• Thickness range: 1mm to 50mm
• Tolerances: ±0.03mm to ±0.10mm depending on size
• Magnetization direction: Axial (through thickness), diametral (across diameter), or multi-pole
• Grade selection: N35 to N52, with temperature suffixes M, H, SH, UH, EH
• Coatings: Ni-Cu-Ni, epoxy, zinc, gold, passivation

Custom disc magnets are widely used in prototype motor development, sensor arrays, and specialized holding assemblies. The ability to specify exact magnetic flux orientation ensures optimal system efficiency.

Ningbo Tujin Magnetic Industry Co., Ltd: Your NdFeB Disc Magnet Partner

As a dedicated custom neodymium disc magnet manufacturer, Tujin provides engineering support from initial concept to production, ensuring that your Neodymium NdFeB Disc Magnets meet exact specifications. For high-temperature environments, our high temperature neodymium disc magnet grades (SH/UH/EH) offer reliable performance under thermal stress.

Frequently Asked Questions (FAQ) About NdFeB Disc Magnets