Powerful 40mm x 20mm x 10mm Neodymium – Black Epoxy Coated Rare Earth Magnet

Powerful 40mm x 20mm x 10mm Neodymium – Black Epoxy Coated, Rare Earth Magnet

2025-7-15

Understanding Neodymium Magnets

Neodymium (NdFeB) magnets are known for their exceptional magnetic strength, making them the strongest type of permanent magnet on the market. Their compact size allows them to deliver high magnetic force even in space-constrained applications. In construction, they help securely position metal components during assembly, while in the medical sector, they play a vital role in the consistent performance of imaging systems and sensitive equipment. From everyday home tasks to demanding industrial operations, these magnets ensure dependable, long-lasting functionality.

40mm x 20mm x 10mm Neodymium – Black Epoxy Coated, Rare Earth Magnet

This 40mm x 20mm x 10mm neodymium block magnet is engineered from powerful N50 grade rare earth material, delivering exceptional holding force in a compact size. Coated with durable black epoxy, it combines high magnetic performance with enhanced corrosion resistance, making it ideal for both indoor and challenging industrial environments.

With a pull force of up to 27.28KG kg, this magnet is a trusted choice for demanding applications across engineering, automotive, manufacturing, construction, and more.

Magnet Grade: N50

These N50 grade neodymium magnets deliver exceptional magnetic strength, with a maximum energy product of approximately 50 MGOe (Mega Gauss Oersted). Designed for high-performance applications, they provide consistent and reliable magnetic force across a wide range of uses. Their powerful pull makes them ideal for both advanced industrial tasks and everyday applications that require superior magnetic performance.

Surface Finish: Black epoxy Coating

These magnets are finished with a black epoxy coating that enhances corrosion resistance and maintains a clean, professional look. This layered shield protects the magnet’s core from oxidation and wear in mildly humid environments, making them suitable for long-term use in a range of settings. For more aggressive environments, epoxy or other advanced coatings may offer enhanced protection.

APPLICATION EXAMPLES

Material Neodymium (NdFeB)

Product Name: Black Epoxy Coated, Rare Earth Magnet

Shape: Channel, Mounting, Block,

Magnetic Grade: N50 (Br ≥ 14.6 kGs, Hcj ≥ 12 kOe)
Dimensions: L40mm x 20mm x 10mm (customizable)
Dimensional Tolerance: Length ±0.05mm, Width ±0.05mm, Thickness ±0.05mm
Operating Temperature: ≤80°C (high-temp version available)
Density: ≥7.5 g/cm³

Max Gauss: 1850

Pull (KG): 17.04
Surface Magnetic Field: 3800 ±200 Gauss (measured with TM-801 Gauss meter)
Magnetic Flux: 2.3 mWb (measured with fluxmeter)

Manufacturing Process

The product is manufactured through the following key processes:

● A high-speed grinding wheel shapes the magnet's surfaces with tight dimensional tolerances.

● Coolant fluid is applied to control heat, reduce surface stress, and ensure a smooth finish.

● The result is a uniform, precisely dimensioned magnet with clean edges—ideal for high-performance applications.

This precision step is essential for ensuring that the final magnets meet strict quality standards for use in motors, sensors, electronics, and aerospace components  

Surface Treatment & Plating

To enhance corrosion resistance and appearance:

Default Plating: Triple-layer Epoxy (customizable).

Standard Thickness:12μm

Optional Plating: Single-layer Zn (5μm) for cost-sensitive projects.

Features:

✔ Salt spray & oxidation resistance

✔ Increased surface hardness (scratch-resistant)

✔ Improved gloss (ideal for exposed components)

Appearance & Dimensional Inspection

Visual Inspection: Under standardized lighting, trained QC staff check for cracks, chipping, inclusions, pores, or oxidation

Automated Intelligent Inspection: High-speed cameras with AI algorithms detect and reject defects (e.g., cracks, scratches, discoloration) and dimensional anomalies, improving yield and reducing human error. 

Magnetic Flux Consistency Test: Fluxmeters or Hall-effect testers measure magnetic flux across batches to ensure uniform performance in end-user applications.

Reliability Testing

Impact & Vibration Test: Simulates shipping and usage conditions to ensure operational stability.

Constant Temperature & Humidity Test: Performed under 85°C and 85% RH for 96–500 hours. Performance and appearance are compared before and after testing.

Applications

Electric Motors & Generators
Application: Precision-engineered magnets are employed in stators, rotors, and brushless DC motors to enhance magnetic flux density, efficiency, and torque performance.

Consumer Electronics
Application: High-performance neodymium magnets are integrated into speakers, haptic systems, vibration motors, and sensors, contributing to compact design and reliable functionality.

Packaging & Transportation

Defect Elimination: 100% inspection using calipers, projectors, visual checks, and automated systems to reject cracked, chipped, oxidized, or coated-defective magnets.

Uniform Magnetization & Structured Arrangement: Magnets are uniformly magnetized and arranged for optimal packaging based on customer requirements to ensure performance and facilitate automated assembly.

Vacuum Sealed Packaging: Multi-layer vacuum sealing with moisture barriers, desiccants or nitrogen, prevents corrosion and magnetic interference during storage and shipping.

Customized Outer Packaging: Shock-proof, moisture-resistant, and anti-magnetic leakage packaging (e.g., multilayer cartons, plastic boxes, metal shielding) ensures compliance with international logistics standards. Each box includes a product list, labels, and tracking codes.

Frequently Asked Questions:

Q: How to choose the correct magnetization direction?

Axial Magnetization: Magnetic lines flow through thickness — best for concentrated fields

Radial Magnetization: Magnetic lines radiate outward — for uniform field distribution

Multipole Magnetization: Multiple poles along circumference — for complex fields (e.g., motors, sensors)

Q: What is the maximum working temperature of a ring magnet?

Standard N-series: up to 80°C

High-temp grades (SH/UH/EH): up to 150°C–230°C

Dysprosium-enriched formulations can further enhance temperature resistance

Q: Does magnetism decay over time?

Under normal conditions (room temp, dry, no heavy vibration), NdFeB magnets exhibit excellent time stability (<5% loss over 10 years). However, factors like:

● Temperature overrun

● Strong external magnetic fields

● Surface corrosion

● Mechanical impact may affect performance.

Why Choose us ？

Dongguan Jinconn New Materials Co., Ltd. is a publicly listed enterprise offering integrated R&D, manufacturing, and sales of rare earth magnets. Based in Xiaohe Industrial Zone, Daojiao Town, Dongguan, we serve clients across China and globally. 

With deep expertise in magnetic materials, we deliver solutions for industries like EVs, smart manufacturing, and electronics. Our strong technical capabilities and product consistency have earned the trust of customers worldwide.

Usage Precautions？

● Handle gently: Avoid impacts/drops (brittle material).

● Prevent pinching: Slide magnets apart—do not pry.

● Polarity check: Install correctly to avoid malfunctions.

● Avoid moisture/acids: Store in dry, mild environments.

● Keep away from sensitive devices: Hard drives, IC cards, pacemakers, etc.

Customization & Services

● Custom magnet size, shape, and coating (layers, thickness, color)

● Tailored magnetization direction and field strength

● Laser engraving service for logos or serial numbers

● Packaging and suction force testing for special applications

Please contact us for free samples, magnet customization solutions, and MSDSRoHS, ISO 9001, QC080000, IATF 16949, ISO 14001, ISO 27001 or other relevant certificates!

We’re here to help!

 Phone/WhatsApp/WeChat: +86 180 3822 5893
 Email: info@jinconn.com
 Website: www.jinconnmagnet.com
 Address: Xiaohe Industrial Zone, Daojiao