Frequently Asked Question about NdFeB Magnet








l Inspection standard for permanent magnet

l Purchasing Guide

l Permanent magnet supply direction

l Surface protection and surface coating for the permanent magnet

l Quality warranty

l Safety principle for manual operation of permanent magnet

Sintered NdFeB Magnet

Sintered Neodymium Iron Boron (NdFeB), the most powerful Rare Earth magnet available today, possesses high energranging from 8MGOe to 52MGOe and wonderful coercive force. As the third generation of Rare Earth permanent magnet, NdFeB products are quite a bit less expensive, and are mechanically stronger and less brittle than SmCo, also density of NdFeB products is about 13% smaller than SmCo products. Because NdFeB magnets are more prone to oxidation than any other magnet alloy, for most applications, coating or plating the magnets is recommended.

sintered ndfeb magnets

Super-Strength Rare Earth Magnet—Sintered NdFeB magnets, have the characteristics of:

  • Extreme strong Br Resident induction.
  • Excellent demagnetization resistance capability.
  • Good Price relative to its high magnetic properties.
  • Coating is needed for NdFeB.
  • Surface Treatment Method: Type Information
    Metallic Zinc, Nickel, Nickel+Nickel, Copper+Nickel, Nickel+Copper+Nickel
    Gold, Organic Epoxy, Nickel+Epoxy coating
    Temporary Surface: Passivation

    Manufacturing Method:
    Sintered NdFeB Magnet —fine NdFeB powder is compacted in a die and then sintered, fusing the powder into a solid material. There are 2 forms of pressing: die pressing (which involves a hard die into which the powder is placed and then pressed), and isostatic pressing (involving a special "rubber" die into which powder is placed and then pressed with equal force in all directions on the powder). Die pressed parts are usually made smaller than isostatically pressed parts. Although the magnetic properties of isostatically pressed parts are higher, the uniformity of magnetic characteristics is usually lower than that of die pressed parts. Sintered parts normally need some finish machining in order to meet final tolerances.

    Machining:
    Some machining operations may be performed on NdFeB materials using carbide tools, although surface finishes thus obtained may be less than optimal. In general, NdFeB magnets must be machined using diamond-grinding techniques. We are fully equipped to machine these materials to your blueprint specifications.

    Magnetizing and Handling:
    Rare Earth materials are mechanically weak, and magnetically very strong. They must therefore be handled very carefully to avoid damage and injury to personnel handling the magnets.
    All NdFeB magnets require extremely high magnetizing fields and special consideration must be given to this when designing complex assemblies, if it is intended to magnetize after assembly.

    Temperature Effects:
    Magnetic properties of NdFeB deteriorate rapidly above about 130°C, depending on the grade of material, and the permeance coefficient of the magnet in operation. The higher the permeance coefficient the magnet operates at, the higher the temperature it will withstand. High Hci NdFeB materials operating at a high permeance coefficient can operate to about 220°C.

    Common Applications for Neodymium Iron Boron Magnets:
    Holding systems requiring very high holding forces, high field yoke magnets, high performance stepper, DC, servo, linear, and voice coil motors, magnetic bearings, magnetic couplings, loudspeakers, Halbach arrays, headphones, microphones, magnetic separation, instrumentation, switches, relays, magnetic resonance, sputtering, vacuum deposition, charged particle beam guidance, particle accelerators, Undulators, Wigglers, and others.

    Acoustics
    Acoustics
    Communcation equipment
    Communcation equipment
    Home appliance
    Home appliance
    IT industry
    IT industry
    Motor assemblies
    Motor assemblies
    MRI
    MRI
    Transportion
    Transportion
    Windmill
    Windmill

    Shapes and Sizes Available:
    In addition to the stock shapes, sizes, and grades listed, others are available. Please inquire. Non-standard shapes and sizes can be fabricated to blueprint specifications from raw stock.

    Magnetic and Physical Properties

    Sintered NdFeB Magnetic Properties
    TYPE Remanence
    Br
    Coercive force
    bHc
    Intrinsic coercive force
    iHc
    Max. energy product
    (BH) max
    Working MAGNETIC AND PHYSICAL CHARACTERISTICS (NdFeB) Temperature
    KGs T KOe KA/m KOe KA/m MGOe KJ/m3 °C
    N-30 10.8-11.2 1.08-1.12 9.8-10.5 780-836 ≥12 ≥955 28-30 223-239 ≤80
    N-33 11.4-11.7 1.14-1.17 10.5-11.0 836-876 ≥12 ≥955 31-33 247-263 ≤80
    N-35 11.7-12.1 1.17-1.21 10.8-11.5 860-915 ≥12 ≥955 33-35 263-279 ≤80
    N-36 11.9-12.2 1.19-1.22 10.8-11.5 860-915 ≥12 ≥955 34-36 271-287 ≤80
    N-38 12.2-12.6 1.22-1.26 10.8-11.5 860-915 ≥12 ≥955 36-38 287-303 ≤80
    N-40 12.6-12.9 1.26-1.29 10.5-11.0 836-876 ≥12 ≥955 38-40 303-318 ≤80
    N-42 12.9-13.2 1.29-1.32 10.5-11.0 836-876 ≥12 ≥955 40-42 318-334 ≤80
    N-43 13.0-13.3 1.30-1.33 10.5-11.0 836-876 ≥12 ≥955 41-43 326-342 ≤80
    N-45 13.3-13.7 1.33-1.37 10.5-11.0 836-876 ≥12 ≥965 43-45 342-358 ≤80
    N-48 13.8-14.2 1.38-1.42 ≥10.5 ≥835 ≥12 ≥955 46-49 366-390 ≤80
    N-50 13.8-14.5 1.38-1.45 ≥10.5 ≥835 ≥11 ≥955 47-51 374-406 ≤80
    N-52 14.3-14.8 1.43-1.48 ≥10.8 ≥860 ≥11 ≥876 50-53 398-422 ≤80
    N-27M 10.2-10.6 1.02-1.06 9.6-10.1 764-804 ≥15 ≥1194 25-27 199-215 ≤100
    N-30M 10.8-11.2 1.08-1.12 10.1-10.6 804-844 ≥15 ≥1194 28-30 223-239 ≤100
    N-33M 11.4-11.7 1.14-1.17 10.5-11.0 844-884 ≥15 ≥1194 31-33 247-263 ≤100
    N-35M 11.7-12.1 1.17-1.21 10.8-11.5 860-915 ≥15 ≥1114 33-35 263-279 ≤100
    N-36M 11.9-12.2 1.19-1.22 11.1-11.6 884-923 ≥15 ≥1194 34-36 271-287 ≤100
    N-38M 12.2-12.6 1.22-1.26 10.8-11.5 860-915 ≥14 ≥1114 36-38 287-303 ≤100
    N-40M 12.6-12.9 1.26-1.29 10.8-11.5 860-915 ≥14 ≥1114 38-40 303-318 ≤100
    N-42M 12.9-13.2 1.29-1.32 10.8-11.4 860-907 ≥14 ≥1114 40-42 318-334 ≤100
    N-45M 13.3-13.7 1.33-1.37 10.8-11.4 860-907 ≥17 ≥1114 43-45 334-358 ≤100
    N-48M 13.6-14.0 1.36-1.40 ≥11.8 ≥939 ≥14 ≥1114 46-49 366-390 ≤100
    N-50M 14.0-14.5 1.40-1.45 ≥13.0 ≥1033 ≥14 ≥1114 48-51 382-406 ≤100
    N-27H 10.2-10.6 1.02-1.06 9.6-10.1 764-804 ≥17 ≥1353 25-27 199-215 ≤120
    N-30H 10.8-11.2 1.08-1.12 10.1-10.6 804-844 ≥17 ≥1353 28-30 223-239 ≤120
    N-33H 11.4-11.7 1.14-1.17 10.6-11.1 844-884 ≥17 ≥1353 31-33 247-263 ≤120
    N-35H 11.7-12.1 1.17-1.21 10.8-11.5 860-915 ≥17 ≥1353 33-35 263-279 ≤120
    N-36H 11.9-12.2 1.19-1.22 11.1-11.6 884-923 ≥17 ≥1353 34-36 271-287 ≤120
    N-38H 12.2-12.6 1.22-1.26 11.5-12.0 915-955 ≥17 ≥1353 36-38 287-303 ≤120
    N-40H 12.6-12.9 1.26-1.29 11.5-12.0 915-955 ≥17 ≥1353 38-40 303-318 ≤120
    N-42H 12.9-13.2 1.29-1.32 11.5-12.0 915-955 ≥17 ≥1353 40-42 318-334 ≤120
    N-45H 13.2-13.8 1.32-1.38 ≥12.0 955 ≥17 ≥1353 42-46 335-366 ≤120
    N-46H 13.3-13.8 1.33-1.38 ≥12.2 972 ≥16 ≥1274 44-47 350-374 ≤120
    N-48H 13.6-14.3 1.36-1.43 ≥12.5 995 ≥16 ≥1274 46-49 366-390 ≤120
    N-27SH 10.2-10.6 1.02-1.06 9.6-10.1 764-804 ≥20 ≥1592 25-27 199-215 ≤150
    N-30SH 10.8-11.2 1.08-1.12 10.1-10.6 804-844 ≥20 ≥1592 28-30 223-239 ≤150
    N-33SH 11.4-11.7 11.4-11.7 10.6-11.1 844-884 ≥20 ≥1592 31-33 247-263 ≤150
    N-35SH 11.7-12.1 1.17-1.21 10.8-11.5 860-915 ≥20 ≥1595 33-35 263-279 ≤150
    N-38SH 12.1-12.5 1.21-1.25 10.8-11.5 860-915 ≥20 ≥1592 36-38 287-302 ≤150
    N-40SH 12.6-12.9 1.26-1.29 10.8-11.5 860-915 ≥20 ≥1592 38-40 303-318 ≤150
    N-42SH 12.8-13.2 1.28-1.32 ≥11.8 ≥939 ≥20 ≥1672 40-43 320-343 ≤150
    N-45SH 13.2-13.8 1.32-1.38 ≥12.6 ≥1003 ≥20 ≥1592 43-46 342-366 ≤150
    N25UH 9.8-10.2 0.98-1.02 9.2-9.6 732-764 ≥25 ≥1990 23-25 183-199 ≤180
    N28UH 10.4-10.8 1.04-1.08 9.8-10.2 780-812 ≥25 ≥1990 26-28 207-223 ≤180
    N30UH 10.8-11.3 1.08-1.13 ≥10.2 ≥812 ≥25 ≥1990 28-31 223-247 ≤180
    N35UH 11.7-12.1 1.17-1.21 10.5-11.2 836-890 ≥25 ≥1989 33-35 263-278 ≤180
    N38UH 12.1-12.5 1.21-1.25 ≥11.4 ≥907 ≥25 ≥1990 36-39 287-310 ≤180
    N40UH 12.5-12.8 1.25-1.28 ≥11.4 ≥907 ≥25 ≥1990 38-41 302-326 ≤180
    N28EH 10.4-10.8 1.04-1.08 9.8-10.2 780-812 ≥30 ≥2387 26-28 207-223 ≤200
    N30EH 10.8-11.2 1.08-1.12 10.1-10.6 804-844 ≥30 ≥2387 28-30 223-239 ≤200
    N35EH 11.7-12.1 1.17-1.21 ≥10.2 ≥812 ≥30 ≥2388 33-36 263-287 ≤200
    N38EH 12.1-12.5 1.21-1.25 ≥11.4 ≥907 ≥30 ≥2388 36-39 287-310 ≤200
    N30AH 10.8-11.3 1.08-1.13 ≥10.2 ≥812 ≥35 ≥2785 28-32 223-255 ≤220
    N33AH 11.2-11.7 1.12-1.17 ≥10.2 ≥812 ≥35 ≥2785 31-34 247-271 ≤220

    Remark: The above mentioned data of magnetic and physical characteristics are given at room temperature

    ** The open flux irreversible loss of the testing sample at this temperature ≤5%

    Other Physical Properties (Sintered NdFeB)
    Temp.Coeff.of Br: -0.11%/°C Temp.Coeff.of iHc: -0.60%/°C
    Density: 7.4~7.6g/cm3 Electrical Resistivity: 144µΩcm
    Vickers Hardness: 600HV Flexural Strength: 25kg/mm
    Tensile Strength: 8kg/mm2 Coef. of Thermal Expansion: 4×10-6/°C
    Specific Heat: 0.12kcal/(kg.°C) Thermal conductivity: 7.7kcal/m.h.°C
    Young's Modulus: 1.6×1011N/m2 Rigidity: 0.64N/m2
    Poisson's Ratio: 0.24 Compressibility: 9.8x10-12m2/N
    Curie Temperature: 310~340°C    
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