Neodymium Magnet

Neodymium magnet (aka NdFeB magnet), is the third generation of rare earth magnet, which is composed of Neodymium, Iron, Boron and a few transition metals. With high remanence, high coercive force, high energy product, and high performance /cost, Neodymium magnet is currently the strongest magnet available in the world.


Manufacturing Process


Neodymium, Iron, Boron and a few transition metals will be mixed into the Neodymium powder, then fine Neodymium powder will be compacted in a die and sintered, fusing the powder in a solid state. There are two ways of pressing: die pressing and isostatic pressing. Sintered parts normally need some finish machining in order to meet final tolerances.


Machining & Tolerance

 

Generally, Neodymium magnet must be machined using diamond-grinding techniques. Sometimes, machining operations may be performed on Neodymium materials with carbide tools, but surface finishes thus obtained may be less than optimal. The Standard tolerances for Neodymium magnet is +/- 0.1mm for ground dimensions, but stricter tolerances are possible if specially required.


Surface treatments


The corrosion resistance of Neodymium magnet is considered poor. Surface coating or plating is therefore highly recommended. Almost all kinds of surface coatings are available, like Nickel, Zn, Ni-Cu-Ni, Gold, Silver, Sn, Chrome. We also apply special surface protection to Neodymium magnet, like ABS(Plastic) coating, Rubber coating, PTFE(Teflon) coating, stainless steel case and Epoxy coating etc.


Magnetizing & Packing


Neodymium magnet requires magnetizing fields with extremely high power, and can be magnetized in any direction as long as it is aligned properly. In some instances, multiple pole magnetization is possible with special fixtures. All Neodymium magnet is anisotropic and can only be magnetized in the orientation direction, so particular consideration must be given when designing complex assemblies, if it is intended to magnetize after installation.


Neodymium magnet is mechanically weak but magnetically very strong. They should be packed properly in order to help all users to handle them safely.

 

Magnetic properties of Neodymium magnet

 

Grade Residual Induction Coercive Force Intrinsic Coercive Force Maximum Energy Product Maximum Working Temperature
Br Hcb Hcj (BH)max Tw
mT kA/m kA/m kJ/m3
[kGs] [kOe] [kOe] [MGOe]
N35 1170-1220 ≥868 ≥955 263-287 80°
[11.7-12.2] [≥10.9] [≥12] [33-36]
N38 1220-1250 ≥899 ≥955 287-310 80°
[12.2-12.5] [≥11.3] [≥12] [36-39]
N40 1250-1280 ≥907 ≥955 302-326 80°
[12.5-12.8] [≥11.4] [≥12] [38-41]
N42 1280-1320 ≥915 ≥955 318-342 80°
[12.8-13.2] [≥11.5] [≥12] [40-43]
N45 1320-1380 ≥923 ≥955 342-366 80°
[13.2-13.8] [≥11.6] [≥12] [43-46]
N48 1380-1420 ≥923 ≥955 366-390 80°
[13.8-14.2] [≥11.6] [≥12] [46-49]
N50 1400-1450 ≥955 ≥876 382-406 80°
[14.0-14.5] [≥12.0] [≥11] [48-51]
N52 1430-1480 ≥876 ≥876 398-422 80°
[14.3-14.8] [≥11.0] [≥11] [50-53]
N54 1450-1500 ≥876 ≥876 414-438 70°
[14.5-15.0] [≥11.0] [≥11] [52-55]
35M 1170-1220 ≥868 ≥1114 263-287 100°
[11.7-12.2] [≥10.9] [≥14] [33-36]
38M 1220-1250 ≥899 ≥1114 287-310 100°
[12.2-12.5] [≥11.3] [≥14] [36-39]
40M 1250-1280 ≥923 ≥1114 302-326 100°
[12.5-12.8] [≥11.6] [≥14] [38-41]
42M 1280-1320 ≥955 ≥1114 318-342 100°
[12.8-13.2] [≥12.0] [≥14] [40-43]
45M 1320-1380 ≥955 ≥1114 342-366 100°
[13.2-13.8] [≥12.5] [≥14] [43-46]
48M 1370-1430 ≥1027 ≥1114 366-390 100°
[13.7-14.3] [≥12.9] [≥14] [46-49]
50M 1400-1450 ≥1033 ≥1114 382-406 100°
[14.0-14.5] [≥13.0] [≥14] [48-51]
35H 1170-1220 ≥868 ≥1353 263-287 120°
[11.7-12.2] [≥10.9] [≥17] [33-36]
38H 1220-1250 ≥899 ≥1353 287-310 120°
[12.2-12.5] [≥11.3] [≥17] [36-39]
40H 1250-1280 ≥923 ≥1353 302-326 120°
[12.5-12.8] [≥11.6] [≥17] [38-41]
42H 1280-1320 ≥955 ≥1353 318-342 120°
[12.8-13.2] [≥12.0] [≥17] [40-43]
45H 1320-1370 ≥973 ≥1353 342-366 120°
[13.2-13.7] [≥12.3] [≥17] [43-46]
48H 1370-1420 ≥995 ≥1353 366-390 120°
[13.7-14.2] [≥12.5] [≥17] [46-49]
35SH 1170-1220 ≥876 ≥1592 263-287 150°
[11.7-12.2] [≥11.0] [≥20] [33-36]
38SH 1220-1250 ≥907 ≥1592 287-310 150°
[12.2-12.5] [≥11.4] [≥20] [36-39]
40SH 1250-1280 ≥939 ≥1592 302-326 150°
[12.5-12.8] [≥11.8] [≥20] [38-41]
42SH 1280-1320 ≥963 ≥1592 318-342 150°
[12.8-13.2] [≥12.1] [≥20] [40-43]
45SH 1320-1380 ≥979 ≥1592 342-366 150°
[13.2-13.8] [≥12.3] [≥20] [43-46]
28UH 1040-1080 ≥764 ≥1990 207-231 180°
[10.4-10.8] [≥9.6] [≥25] [26-29]
30UH 1080-1130 ≥812 ≥1990 223-247 180°
[10.8-11.3] [≥10.2] [≥25] [28-31]
33UH 1130-1170 ≥852 ≥1990 247-271 180°
[11.3-11.7] [≥10.7] [≥25] [31-34]
35UH 1170-1220 ≥860 ≥1990 263-287 180°
[11.7-12.2] [≥10.8] [≥25] [33-36]
38UH 1220-1250 ≥899 ≥1990 287-310 180°
[12.2-12.5] [≥11.3] [≥25] [36-39]
40UH 1240-1280 ≥939 ≥1990 302-326 180°
[12.5-12.8] [≥11.8] [≥25] [38-41]
28EH 1040-1080 ≥780 ≥2388 207-231 200°
[10.4-10.8] [≥9.8] [≥30] [26-29]
30EH 1080-1130 ≥812 ≥2388 223-247 200°
[10.8-11.3] [≥10.2] [≥30] [28-31]
33EH 1130-1170 ≥836 ≥2388 247-271 200°
[11.3-11.7] [≥10.5] [≥30] [31-34]
35EH 1170-1220 ≥876 ≥2388 263-287 200°
[11.7-12.2] [≥11.0] [≥30] [33-36]
38EH 1220-1250 ≥899 ≥2388 287-310 200°
[12.2-12.5] [≥11.3] [≥30] [36-39]
28AH 1040-1080 ≥787 ≥2624 207-231 230°
[10.4-10.8] [≥9.9] [≥33] [26-29]
30AH 1080-1150 ≥819 ≥2624 223-247 230°
[10.8-11.3] [≥10.3] [≥33] [28-31]
33AH 1130-1170 ≥843 ≥2624 247-271 230°
[11.3-11.7] [≥10.6] [≥33] [31-34]

 

Physical properties of Neodymium magnet

 

Parameters Units Indicators
Density g/cm3 ≥7.3
Curie temperature 310-340
BrReversible temperature coefficient ℃/% -0.100~-0.130
HcjReversible temperature coefficient ℃/% ﹣0.40~﹣0.70
Compressive strength N/mm2 1050
Bending strength N/mm2 250
Tensile strength N/mm2 80
Webster Hardness   600
Coefficient of thermal expansion(20 to 200℃) 10-6/k ∥5⊥-1.5
Specific heat J/(Kg.K) 460
Thermal conductivity W/(m.K) 9
Resistivity μΩ.cm 150

 

Surface coatings of Neodymium magnet

 

Surface coating Coating method Coating thickness (μm) Coating color Coating features
Nickel Plating ≥ 5 Silver Corrosion resistance strong, with outstanding resistance to high temperature and humidity.
Zinc Plating ≥ 5 Silvery white Has strong corrosion resistance, anti-salt spray test ability.
Gold Plating ≥ 5 Gold Has outstanding resistance to high temperature, corrosion resistance, good resistance to color change ability.
Ni-Cu-Ni Plating 15-30 Silver strong corrosion resistance.
Epoxy Electrophoresis 15-20 Black / Grey Strong corrosion resistance, outstanding resistance to salt spray, strong resistance to high temperature and humidity.