Neodymium Rectangular Magnets

Zhaobao Magnet Group supplies custom Neodymium Rectangular Magnets for wholesale buyers. Built with 30 years of manufacturing experience, our factory solves large-size sintering distortion through advanced vacuum technology. We ensure strict ±0.05mm tolerances, uniform magnetic flux, and robust anti-corrosion platings. Partnered with CAS, we deliver high-performance magnet solutions worldwide.

Magnetic Parameters Br, Hcj, BHmax and Temperature Capabilities (IEC Standard Alignment)

To properly specify industrial Bar Magnets for Separators, design engineers must understand the fundamental relationship between key magnetic properties defined under international standards such as IEC 60404-5 (Methods of measurement of the magnetic properties of magnetically hard materials).

Residual Flux Density (Br)

Residual Flux Density, expressed in Tesla (T) or Gauss (G), measures the magnetic induction remaining in a saturated magnet when the magnetic field intensity is reduced to zero. Higher Br values directly correlate with stronger magnetic holding force or higher magnetic flux output in narrow air gaps. For standard Neodymium Rectangular Magnets operating at room temperature, grades like N52 or N54 achieve Br values exceeding 1.45 Tesla.

Coercivity and Intrinsic Coercivity (Hcb and Hcj)

Coercivity represents the resistance of a magnetic material to demagnetization. Normal coercivity (Hcb) indicates the magnetic field strength required to reduce magnetic induction to zero, whereas intrinsic coercivity (Hcj) measures the field strength required to completely reduce internal polarization to zero. In demanding operational environments where Bar Magnets for Separators face reverse magnetic fields or high operating temperatures, a higher Hcj is critical to prevent permanent demagnetization.

Maximum Energy Product (BHmax)

The maximum energy product, measured in Mega-Gauss-Oersted (MGOe) or kilojoules per cubic meter (kJ/m³), defines the maximum magnetic energy density stored within the magnet. It represents the peak product of induction (B) and field strength (H) along the demagnetization curve. Higher BHmax allows engineers to minimize component dimensions while maintaining necessary magnetic performance.

Thermal Coefficients and Working Temperature Relationship

Sintered NdFeB materials feature temperature-dependent characteristics. Temperature coefficients for magnetic induction α(Br) typically range around -0.09% to -0.12% per degree Celsius, while the temperature coefficient for intrinsic coercivity β(Hcj) ranges from -0.50% to -0.65% per degree Celsius. As temperature increases, thermal agitation reduces both Br and Hcj. When selecting Bar Magnets for Separators for elevated temperature applications, engineers must select temperature-resistant grades (M, H, SH, UH, EH, AH series) that maintain sufficient Hcj to prevent irreversible thermal demagnetization at maximum working temperatures.

Precision Sintering Distortion Control for Large Rectangular Magnets

Manufacturing large-scale Neodymium Rectangular Magnets poses severe technical challenges, particularly regarding anisotropic shrinkage and deformation during high-temperature liquid-phase sintering. Because NdFeB powder particles are aligned under a high magnetic field during pressing, the compaction density and shrinkage ratios differ significantly between the parallel direction (alignment axis) and perpendicular direction.

Oriented Magnetic Field Pressing and Density Uniformity

To eliminate density gradients that cause severe warping, Zhaobao Group utilizes advanced strip-casting technology combined with hydrogen decrepitation (HD) and jet milling to produce ultra-fine particles with uniform grain size distribution (3 to 5 microns). During the compaction stage, our automatic multi-cavity magnetic field presses apply real-time pressure feedback to ensure uniform green density throughout large rectangular shapes.

Specialized Sintering Trays and Atmosphere Control

During the vacuum sintering phase at temperatures exceeding 1000°C, high-grade rectangular blocks are placed on specially engineered molybdenum sintering plates with frictionless ceramic coatings. This allows unrestricted microscopic shrinkage, preventing physical drag forces that cause edge curling and bow deformation. Furthermore, our multi-zone computer-controlled vacuum furnaces guarantee temperature field uniformity within ±2°C across the entire furnace volume.

Precision Grinding and In-Line Inspection

Following sintering and multi-stage heat treatment (annealing), our large Neodymium Rectangular Magnets undergo high-precision double-disc surface grinding, wire EDM, and CNC slicing. Integrated high-speed laser measuring systems monitor dimensional accuracy across length, width, and thickness in real time, ensuring strict compliance with tight mechanical tolerances (±0.05mm or tighter).

Application Selection Guide: Grades, Coatings, and Working Conditions

Selecting the correct magnet grade and surface protection is essential for long-term operational stability. Below is our engineering selection matrix for Bar Magnets for Separators tailored to specific industrial environments:

Procurement & Quality Assurance Guide

Zhaobao Magnet Group guarantees full transparency, rigorous quality control, and zero-defect manufacturing standards under ISO/IATF 16949 certification. Every shipment of custom Bar Magnets for Separators undergoes 100% magnetic flux testing and dimensional verification.

Dimensional Tolerance Verification Checklist

Before issuing custom production runs, please review and confirm the following physical parameter specifications with our technical engineering team:

• Length (L) × Width (W) × Thickness (T): Define dimensions in millimeters (mm) with required tolerances (Standard: ±0.05mm; Precision: ±0.02mm).
• Direction of Magnetization: Specify whether orientation is through the thickness (oriented along T), along the length (L), or across the width (W).
• Corner Chamfers / Radii: Indicate required edge treatments (e.g., C0.5mm chamfer or R0.5mm rounded edges) to prevent chipping during assembly.
• Coating Specifications: Define surface treatment thickness (e.g., Ni-Cu-Ni 12-25 microns) and required salt spray resistance hours (e.g., 48h, 96h, 240h).
• Thermal Operating Limit: Confirm continuous and peak operating temperatures to ensure correct coercivity selection.

Free Sample Application Process

We provide complimentary sample testing for qualified OEM/ODM projects to accelerate your design cycle:

1. Technical Requirement Submission: Contact our sales engineering team with your technical drawings, target application details, and quantities.
2. Engineering Evaluation & CAD Review: Our R&D team reviews your design within 24 hours to verify magnetic feasibility and tolerance stacks.
3. Sample Manufacturing: Standard dimensional samples are dispatched within 3 to 5 business days; custom sintered prototypes within 7 to 10 days.
4. Performance Test Report Included: Every sample package includes hysteresis curve (demagnetization curve) test reports, coating thickness reports, and dimensional inspection sheets.

About Zhaobao Magnet Group

Established in the 1990s, Zhaobao Magnet Group is a 30-Year Magnet Factory and one of the earliest enterprises engaged in the production of rare earth magnets in China. After 30 years of development, continuous investment, and rigorous research and development in the field of strong magnets, Zhaobao Group has grown into a large permanent magnet product manufacturer integrating research and development, production, and sales. Our main magnet factory covers an area of 60,000 square meters and employs over 500 skilled staff members. Today, our annual output of high-grade strong neodymium magnets exceeds 8,000 tons, establishing our position as a leading permanent magnet production base in China.

Zhaobao Group specializes in manufacturing various permanent magnets, including neodymium magnets, Ferrite magnets, SmCo magnets, and AlNiCo magnets. These products serve diverse global sectors, including automotive engineering, electronics, telecommunications, medical equipment, aerospace, and industrial automation. Leveraging magnet technologies as our core competence, we also develop custom magnetic assemblies, magnetic tools, magnetic toys, and specialized mechanical equipment. Beyond standard dimensions, we excel in offering tailored engineering design, precision machining, and custom manufacturing for high-performance Neodymium Rectangular Magnets that precisely meet stringent customer engineering requirements.

Frequently Asked Questions 

Q1: If Neodymium Rectangular Magnets chip or fracture during assembly, who is responsible?

Sintered neodymium magnets are inherently brittle materials due to their intermetallic crystal structure. If damage occurs due to inadequate packaging or transit handling, Zhaobao Group takes full responsibility and provides immediate free replacements. If cracking occurs during your internal assembly due to improper handling, our engineering team will assist in designing specialized non-magnetic assembly jigs and protective bumpers to prevent chipping.

Q2: What happens if magnets lose magnetization during ocean freight shipping or aerial transport?

Unshielded magnets can suffer demagnetization or cause transport hazards if exposed to strong external fields or severe temperature swings. Zhaobao Group packages all exports using custom magnetic shielding containers (iron-lined boxes) compliant with IATA Dangerous Goods Regulations and ocean freight standards. We guarantee zero performance loss or demagnetization during transit under normal logistics conditions.

Q3: How do you guarantee magnetic consistency across a large batch of 100,000 rectangular pieces?

We utilize automated 100% magnetic flux screening equipment alongside statistical process control (SPC). Each magnet batch is tested for Br, Hcj, and maximum energy product consistency. We guarantee that the surface magnetic field deviation within the same batch is held strictly within ±1.5% to ±2.0%.

Q4: Can Neodymium Rectangular Magnets be directly machined or drilled after sintering?

Direct mechanical cutting or drilling with standard steel tools after sintering is strongly discouraged, as local heating can trigger thermal demagnetization and spark combustion of NdFeB powder. All complex shaping, slotting, or hole drilling must be performed prior to final magnetization using diamond wire sawing or CNC ultrasonic grinding under continuous liquid coolant flow.

Q5: How does Zhaobao Magnet Group assist when we experience unexpected motor loss of excitation?

In partnership with the "Permanent Magnet Motor Magnet Engineering Technology Center" (co-established with the Chinese Academy of Sciences), our technical team conducts failure analysis on degraded magnets. We test thermal history, microstructural oxidation, and demagnetization curves to pinpoint the root cause—whether thermal overload, reverse field spikes, or coating failure—and supply re-engineered high-coercivity replacement grades (e.g., switching to SH, UH, or EH series).