China permanent magnet manufacturer:

N38 NdFeB Block Magnet F15mm*6.25mm*1mm

Port: Ningbo or Shanghai, China 
Production Capacity: 500000000PCS/Season
Payment Terms: L/C, T/T, D/P, Western Union, Paypal, Money Gram
Magnetization Direction: Axial/Radial/Multi-Poles Magnetization
Color: Silver, golden
Coating: Nickel,Copper,Gold,Silver,Zinc
Grade: N35-N52
Shape: Block,disc,cylinder,mesopore,ring,rod,sphere,cube,neocube,tube,arc,cone
Material: Sintered Neodymium-Iron-Boron
HS Code: 8505111000
Tolerance: +/- 0.05mm
Transport Package: Carton, Wood Case, Anti-Magnetized Package
Sample: Avaliable
OEM: Acceptable
Application: Electronic Products, Speaker Magnet, Industrial Magnet, Jewelry Magnet, Solenoid, Motor Magnet


Specification of N38 NdFeB Block Magnet F15mm*6.25mm*1mm
Texture of material N38
Remanence Br 1.249T 12.49KGs
Coercivity Hcb 965.4kA/m 12.13kOe
Intrinsic coercivity Hcj 1037 kA/m 13.03kOe
Maximum magnetic energy product (BH) max 37.9MGOe
Size Length 15mm * width 6.25mm * thickness 1mm
Tolerance Length width ± 0.05mm, thickness ± 0.1mm
Coating Zinc
Magnetization direction Axial magnetization
Surface magnetic field 1900-2500GS
Working temperature The maximum working temperature is 80 ℃

Magnetic Characteristics of N38

Br (Residual Induction) Br (Residual Induction) Hcb (Coercive Force) Hcb (Coercive Force) Bhmax (Maximum Product Energy) Bhmax (Maximum Product Energy) Hcj (Intrinsic Coercive Force) Hcj (Intrinsic Coercive Force)
mT KGs KA/m KOe KJ/m³ MGOe KOe KA/m
1.23-1.26 12.3-12.6 899 11.3 287-311 36-39 12 955

Thermal Characteristics of N38

Max Operating Temp Curie Temp Reversible Temp Coeff Rev Temp Coeff
°C %/°C Br (TC a(Br) %/°C) Hcj (Tc a(Hcj) %/°C)
80 310 -0.12 -0.75

Mechanical/Physical Characteristics of N38


Grade & Working Temperature:


Max Operating Temperatures


80°C     (176°F)


100°C   (212°F)


120°C   (248°F)


150°C   (302°F)


180°C   (356°F)

Neodymium Special Shaped Magnets with other Coating are also available:

Coating Type Overall Thickness Salt Spray Test Pressure Cooker Test
Ni-Cu-Ni (Nickel) 15-21 μm 24 hours 48 hours
NiCu + Black Nickel 15-21 μm 24 hours 48 hours
NiCuNi + Epoxy 20-28 μm 48 hours 72 hours
NiCuNi + Gold 16-23 μm 36 hours 72 hours
NiCuNi + Silver 16-23 μm 24 hours 48 hours
Zinc 7-15 μm 12 hours 24 hours

Each individual layer of Nickel and Copper are 5-7 μm thick. The Gold and Silver Coating layers are 1-2 μm thick. Test results shown to allow comparison between Coating options. Performance in your application under your specific test conditions may vary. Salt Spray testing conducted with a 5% NaCl solution, at 35°C. Pressure Cooker Test (PCT) conducted at 2 atm, 120°C at 100% RH.

Shape Max Size Min Size
Block L240*100*50mm L1*1*0.5mm
Disc/Cylinder D240*50mm D1*0.5mm
Ring OD240*40mm (hole size flexible as requested) D1.5*0.5*1mm
Countersunk OD240*40mm (hole size flexible as requested) D8*2.5mm (hole size as customized)

Other special shapes

per as your request per as your request

How to detect the quality of bock magnet?

The quality of strong NdFeB magnet is evaluated from two aspects: 1. Product performance; 2. Product appearance.

Product performance

There is a unified standard for the properties of Nd-Fe-B. the main indexes include magnetic energy product, coercivity and remanence.

Product appearance

Appearance inspection can be divided into five categories:

  • 1. Scratches (including scratches, line marks, knife marks, etc.);

  • 2. Pockmarks (including pockmarks, pockmarks, bubbles, scars, slag layer, local thickness, electroplating tumor);

  • 3. Cracks (including cracks, cracks, etc.);

  • 4. Edge chipping (including edge chipping, edge chipping and material residue);

  • 5. Sand hole (including sand hole, air hole, pinhole, particle, etc.) to see whether there are missing edges and corners, whether the electroplated coating is in good condition, and whether the size meets the design requirements; Neodymium iron boron is generally electrodeposited to protect it from corrosion and rust. It is usually placed on a plane that can be adsorbed with a magnet of the same specification, such as a patch, blade, iron door, etc. the size of the magnetic force can be distinguished by the hand feeling.

Testing method of NdFeB block magnet

  • 1. For the products provided by the new supplier, according to the drawing requirements, first measure the overall dimension, and then measure the magnetic induction intensity with Gauss meter according to the brand of the magnet to check whether it is within the required range. Whether the magnetization direction is correct.
  • 2. Conduct temperature rise and demagnetization test for 3-5 samples, mark three positions on each magnet, measure the magnetic induction strength of each magnet at three positions at room temperature, then put the magnet into the high temperature box, set the temperature at 75 ℃ and heat it at high temperature for 1 hour, then take out the magnet to measure the magnetic induction strength of the same three positions, make a record, cool it to room temperature, and then measure it in turn. Then set the temperature of high temperature box to 85 ℃ and 95 ℃ for measurement respectively, and the measurement method is the same as that of 75 ℃.
  • 3. Check the measurement statistics, the demagnetization amount is less than 1% at 85 ℃
  • 4. The salt spray test has been done by the supplier and the test report has been provided. The test time is more than 48 hours.
  • 5. For the magnets used in batches, the appearance and dimension, magnetic induction strength of each batch shall be inspected to ensure the consistency within the batch: the open circuit magnetic flux is less than 2%, and the magnetic flux between batches is less than 3%
  • 6. Several important technical parameters of magnets, such as coercivity, intrinsic coercivity and remanence, can not be measured. In the past, the supplier provided the testing parameters, and in the future, we can take a few pieces of each batch to a special testing agency for inspection.

Detection tools used

Micrometer, vernier caliper, Gauss meter, fluxmeter, film thickness meter and other measuring tools are generally used in the detection of finished NdFeB magnets.
The film thickness meter mainly measures the plating layer thickness of NdFeB magnet. The film thickness meter can effectively monitor the plating quality and flexibly adjust the magnet plating.
Micrometer and vernier caliper are mainly used to measure the tolerance of NdFeB magnet. The unit is mm.
Gauss meter is mainly used to measure the magnetic force of a point on the surface of the magnet, unit Gauss. Because the magnetic force of each point on the surface of the magnet is different, and the edge magnetic force is higher than that of the center point, the measured data error is too large.
Fluxmeter mainly measures the magnetic force of one side of NdFeB magnet, in Weber WB. Compared with Gauss meter, fluxmeter measures more objective and accurate data.
China Block Magnets Manufacturer supplies N38 block magnets, rare earth neodymium block magnets, ndfe block magnets, rectangular neo permanent magnets , magnetic block magnets for scientific experiments or for industrial applications.

This product is not a toy and is not to be used by children. This product is to be used for scientific experiments or for industrial applications. This product contains strong Neodymium magnet(s) that can be harmful or fatal if swallowed. Strong Neodymium magnets are fragile, they are brittle and will break or chip if they hit a hard surface or are snagged together. Always use the utmost care when handling Neodymium magnets.

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