Black epoxy coated Ferrite countersunk magnets 25x20mm hole 6mm 

Product Overview & Application Scenarios

Experience the outstanding performance of our 20mm x 10mm x (5.2mm countersunk hole) Ferrite disc magnets, engineered for a wide variety of challenging applications. Renowned for their stability and ability to withstand high temperatures, these high performance black epoxy coated  corrosion resistant Ferrite countersunk magnets 25x20mm hole 6mm  are perfectly suited for automotive sensors, electric motors, renewable energy systems, audio devices, and scientific instruments. Upgrade your projects with the long-lasting strength and dependable quality of our premium Ferrite disc magnets.

These Y35 ferrite magnets deliver excellent magnetic power for both everyday users and industry professionals. With a maximum energy product of 4.0 MGOe, they ensure reliable and steady magnetic force in motors, speakers, and holding functions. Praised for their resistance to rust and loss of magnetism, they perform consistently even under harsh conditions. Capable of operating at temperatures up to 250°C, they are a flexible solution for applications in both indoor and outdoor settings.

Technical Specifications

- Product Name: black epoxy coated Ferrite countersunk magnets 25x20mm hole 6mm

- Magnet Grade: Y35 

- Dimension: 20mm x 10mm x (5.2mm Countersunk Hole)

- Dimensional Tolerance: +/-0.05  

- Operating Temperature: ≤250°C

- Density: ≥7.5 g/cm³  

- Surface Magnetic Field: 2,500 Gs  

- Magnetic Flux : 1×10⁻⁴ Wb

Surface Treatment & Coating Technology

To enhance these long-term reliable high remanence black epoxy coated Ferrite countersunk magnets 25x20mm hole 6mm’s corrosion resistance, surface quality, and magnetic stability, the following treatments are used:

Edge Reinforcement: Laser cladding with nickel-based alloy at magnet seams (prevents electrochemical corrosion)

Edge Rounding: Reduces magnetic field distortion

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

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

Optional Coatings: Gold or silver plating for better conductivity and corrosion resistance

Manufacturing Process 

The manufacturing process of this Precision customized strong magnetic force high energy density compact bore magnetic pot ndfeb magnet are as following:

Professional pulse magnetization equipment is used to inject strong and stable magnetic fields, ensuring the magnet meets design specifications and performs reliably under high load or high-frequency operation. 

Appearance & Dimensional Inspection

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

Image Measurement System: High-res cameras and algorithms conduct non-contact 2D measurements, especially for complex or irregular shapes, ensuring efficiency and objectivity in mass production. 

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.

Reliability Testing

To ensure magnet maintain excellent corrosion resistance in complex or harsh environments, the salt spray test is an essential accelerated aging method. It simulates long-term exposure to marine climates, industrial pollution, humidity, or acidic and alkaline conditions, allowing for a reliable evaluation of the protective performance and durability of the magnet's surface coating.

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

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.

We know logistics is more than moving goods — it’s about delivering your promise. Our trusted solutions offer:

Global shipping coverage

Real-time tracking from origin to destination

Enhanced safety at every stage

Dedicated service with customized shipping plans

With our robust land, sea, and air network, your business moves faster, safer, and with complete confidence.

 Why Choose us ？

Dongguan Jinconn New Material Holdings 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.

20+ years of magnet manufacturing expertise

Strict quality control & customization capability

Multilingual technical support with global delivery

RoHS and REACH compliant

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

  Usage Precautions？

⚠ Safety & Handling Guidelines

Handle with care: Neodymium magnets are brittle and can chip or crack if dropped or impacted.

Avoid injury: Always slide magnets apart—do not force or pry them to separate.

Check polarity before use: Incorrect installation may cause malfunction or damage to equipment.

Store properly: Keep in a dry, neutral environment; avoid contact with moisture, acids, or corrosive substances.

Keep away from sensitive electronics: Do not place near hard drives, magnetic cards, pacemakers, or similar devices.

Customization & Services

Customizable magnet dimensions, geometry, and surface coatings (including layer count, thickness, and color)

Precision magnetization orientation and adjustable magnetic field intensity

Optional laser marking for logos, part numbers, or traceability codes

Specialized packaging and pull-force testing tailored to your application needs

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.

Contact Us：

 Phone/WhatsApp/WeChat: +86 13829120676

 Email: Info@jinconn.com

 Address: Xiaohe Industrial Zone, Daojiao Town, Dongguan City, Guangdong Province, China.