Data Sheets
NdFeB Magnets
07/06/2023 Mike Guthrie

In the 1960’s, Dr. Strnat of the University of Dayton had shown that the entire rare earth element family presented an opportunity for developing magnetic compounds.  Samarium is relatively rare in ore deposits, and Cobalt more expensive than the Iron which metallurgist wanted to use.  Consequently, an alternative permanent magnet chemistry was heavily researched.

Dr. John Croat of General Motors and Dr. Masato Sagawa of Sumitomo surprised each other when they both introduced the NdFeB permanent magnet material at the MMM conference in November 1983.  Dr. Croat patented the Nd2Fe14B material in the US and its melt-spinning manufacturing process.  Dr. Sagawa patented the Nd2Fe14B material in Japan and its sintering manufacturing process.

Typical high-energy NdFeB magnets are produced with a sintering process similar to that of SmCo.  However, every producer uses different equipment, process steps, and raw materials to produce their large variety of available grades.

Advantages Disadvantages Major Applications
High energy, high Induction & high coercivity at room temperature, moderate price, large range of magnetic properties. Highly susceptible to rust & corrosion (must be coated), large temperature coefficient of Hcj, rising costs & limited resources of raw materials. Micro motors, industrial motors, HVAC, auto (drive & accessory), aero & marine motors, drone motors, large, small, & transportation generators, speakers, microphones, consumer products, and a large variety of sensor and holding applications.  Other than in some extreme conditions, NdFeB magnets can be used for most applications that require high torque & high efficiency in a small package.

A manufacturing process begins with the prescribed metals and alloys being loaded into a vacuum furnace.  The melted alloy is poured on to a cooled spinning wheel at the exact chill rate to reduce and homogenize the material’s grain size.  The resulting magnet flake is subjected to Hydrogen decrepitation.  This process embrittles the material at the grain boundaries so that the subsequent powder-milling process can provide a uniform material lot with the required particle size distribution.



The NdFeB powder is loaded into a die where it is aligned and pressed.  The resulting green compact is further densified in an isostatic press then loaded into a furnace to sinter & anneal.  The finished block is fabricated to size.  Those parts are treated in an acid bath to remove all oxygen & coolant from their surfaces before coating.  Most processes are executed in an Oxygen-free environment and material testing stations are strategically positioned throughout. 

Today’s RE2Tm14B alloys (RE = Rare Earth, Tm = Transition metal) are widely varied.  Small amounts of Dy, Tb, Co, Sn, Cu, & Ga can improve Hcj and β (temperature coefficient of Hcj) without significantly sacrificing Br.  Additions of Pr, Al, Nb, Zn, Mo, V, W & Ti can also affect Br, α (temperature coefficient of Induction), Hcj, & β.  






Magnetic Properties of Sintered NdFeB Magnets 





Grade Remanence Coercivity Max Energy Product Temperature Coefficient Max Working Temperature
Br HcB HcJ (BH)max Br HcJ TwMax
T kGs kA/m kOe kA/m kOe kJ/m³ MGOe %/°C %/°C ° C
N

N35

 1.17-1.22 11.7-12.2 ≥867 ≥10.9 ≥955 ≥12 263-287 33-36 -0.12 -0.6 80

N38

 1.22-1.25 12.2-12.5 ≥899 ≥11.3 ≥955 ≥12 287-310 36-39 -0.12 -0.6 80

N40

 1.25-1.28 12.5-12.8 ≥907 ≥11.4 ≥955 ≥12 302-326 38-41 -0.12 -0.6 80

N42

 1.28-1.32 12.8-13.2 ≥915 ≥11.5 ≥955 ≥12 318-342 40-43 -0.12 -0.6 80

N45

 1.32-1.37 13.2-13.7 ≥923 ≥11.6 ≥955 ≥12 342-366 43-46 -0.12 -0.6 80

N48

 1.37-1.42 13.7-14.2 ≥875 ≥11.0 ≥955 ≥12 366-390 46-49 -0.12 -0.6 80

N50

 1.39-1.44 13.9-14.4 ≥836 ≥10.5 ≥955 ≥12 374-406 47-51 -0.12 -0.6 80

N52

 1.42-1.47 14.2-14.7 ≥836 ≥10.5 ≥955 ≥12 390-421 49-53 -0.12 -0.6 80

N54

 1.45-1.49 14.5-14.9 ≥836 ≥10.5 ≥876 ≥11 406-438 51-55 -0.12 -0.6 80

N56

 1.48-1.52 14.8-15.2 ≥836 ≥10.5 ≥876 ≥11 414-454 52-57 -0.12 -0.6 80
M

N33M

 1.13-1.17 11.3-11.7 ≥836 ≥10.5 ≥1114 ≥14 247-271 31-34 -0.11 -0.6 100

N35M

 1.17-1.22 11.7-12.2 ≥868 ≥10.9 ≥1114 ≥14 263-287 33-36 -0.11 -0.6 100

N38M

 1.22-1.25 12.2-12.5 ≥899 ≥11.3 ≥1114 ≥14 287-310 36-39 -0.11 -0.6 100

N40M

 1.25-1.28 12.5-12.8 ≥923 ≥11.6 ≥1114 ≥14 302-326 38-41 -0.11 -0.6 100

N42M

 1.28-1.32 12.8-13.2 ≥955 ≥12.0 ≥1114 ≥14 318-342 40-43 -0.11 -0.6 100

N45M

 1.32-1.38 13.2-13.8 ≥995 ≥12.5 ≥1114 ≥14 342-366 43-46 -0.11 -0.6 100

N48M

 1.36-1.42 13.6-14.2 ≥1027 ≥12.9 ≥1114 ≥14 366-390 46-49 -0.11 -0.6 100

N50M

 1.39-1.44 13.9-14.4 ≥1035 ≥13.0 ≥1114 ≥14 374-406 47-51 -0.11 -0.6 100

N52M

 1.42-1.47 14.2-14.7 ≥1059 ≥13.3 ≥1114 ≥14 390-422 49-53 -0.11 -0.6 100

N54M

 1.45-1.49 14.5-14.9 ≥1059 ≥13.3 ≥1114 ≥14 406-438 51-55 -0.11 -0.6 100
H

N33H


 1.13-1.17 11.3-11.7 ≥836 ≥10.5 ≥1353 ≥17 247-271 31-34 -0.11 -0.6 120

N35H


 1.17-1.22 11.7-12.2 ≥868 ≥10.9 ≥1353 ≥17 263-287 33-36 -0.11 -0.58 120

N38H


 1.22-1.25 12.2-12.5 ≥899 ≥11.3 ≥1353 ≥17 287-310 36-39 -0.11 -0.58 120

N40H


 1.25-1.28 12.5-12.8 ≥923 ≥11.6 ≥1353 ≥17 302-326 38-41 -0.11 -0.58 120

N42H


 1.28-1.32 12.8-13.2 ≥955 ≥12.0 ≥1353 ≥17 318-342 40-43 -0.11 -0.58 120

N45H


 1.32-1.37 13.2-13.7 ≥955 ≥12.0 ≥1353 ≥17 342-366 43-46 -0.11 -0.58 120

N48H


 1.36-1.42 13.6-14.2 ≥995 ≥12.5 ≥1353 ≥17 366-390 46-49 -0.11 -0.58 120

N50H


 1.39-1.44 13.9-14.4 ≥1035 ≥13.0 ≥1353 ≥17 374-406 47-51 -0.11 -0.58 120

N52H


 1.42-1.47 14.2-14.7 ≥1035 ≥13.0 ≥1353 ≥17 390-422 49-53 -0.11 -0.58 120

N54H


 1.45-1.49 14.5-14.9 ≥1059 ≥13.3 ≥1273 ≥16 406-438 51-55 -0.11 -0.58 120
SH

N33SH


 1.13-1.17 11.3-11.7 ≥844 ≥10.6 ≥1592 ≥20 247-271 31-34 -0.11 -0.55 150

N35SH


 1.17-1.22 11.7-12.2 ≥876 ≥11.0 ≥1592 ≥20 263-287 33-36 -0.11 -0.55 150

N38SH


 1.22-1.25 12.2-12.5 ≥907 ≥11.4 ≥1592 ≥20 287-310 36-39 -0.11 -0.55 150

N40SH


 1.25-1.28 12.5-12.8 ≥939 ≥11.8 ≥1592 ≥20 302-326 38-41 -0.11 -0.55 150

N42SH


 1.28-1.32 12.8-13.2 ≥987 ≥12.4 ≥1592 ≥20 318-342 40-43 -0.11 -0.55 150

N45SH


 1.32-1.37 13.2-13.7 ≥979 ≥12.3 ≥1592 ≥20 342-366 43-46 -0.11 -0.55 150

N48SH


 1.36-1.42 13.6-14.2 ≥995 ≥12.5 ≥1592 ≥20 358-390 45-49 -0.11 -0.55 150

N50SH


 1.39-1.45 13.9-14.5 ≥995 ≥12.5 ≥1592 ≥20 374-406 47-51 -0.11 -0.55 150

N52SH


 1.42-1.47 14.2-14.7 ≥1035 ≥13.0 ≥1592 ≥20 390-422 49-53 -0.11 -0.55 150

N54SH


 1.45-1.49 14.5-14.9 ≥1059 ≥13.3 ≥1592 ≥20 406-438 51-55 -0.11 -0.55 150
UH

N28UH

 1.04-1.08 10.4-10.8 ≥764 ≥9.6 ≥1990 ≥25 207-231 26-29 -0.1 -0.5 180

N30UH

 1.08-1.13 10.8-11.3 ≥812 ≥10.2 ≥1990 ≥25 223-247 28-31 -0.1 -0.5 180

N33UH

 1.13-1.17 11.3-11.7 ≥852 ≥10.7 ≥1990 ≥25 247-271 31-34 -0.1 -0.5 180

N35UH

 1.17-1.22 11.7-12.2 ≥860 ≥10.8 ≥1990 ≥25 263-287 33-36 -0.1 -0.5 180

N38UH

 1.22-1.25 12.2-12.5 ≥876 ≥11.0 ≥1990 ≥25 287-310 36-39 -0.1 -0.5 180

N40UH

 1.25-1.28 12.5-12.8 ≥915 ≥11.5 ≥1990 ≥25 302-326 38-41 -0.1 -0.5 180

N42UH

 1.27-1.32 12.7-13.2 ≥955 ≥12.0 ≥1990 ≥25 318-342 40-43 -0.1 -0.5 180

N45UH

 1.32-1.37 13.2-13.7 ≥995 ≥12.5 ≥1990 ≥25 342-366 43-46 -0.1 -0.5 180

N48UH

 1.38-1.42 13.8-14.2 ≥1031 ≥12.9 ≥1990 ≥25 366-390 46-49 -0.1 -0.5 180

N50UH

 1.39-1.44 13.9-14.4 ≥1035 ≥13.0 ≥1990 ≥25 374-406 47-51 -0.1 -0.5 180

N52UH

 1.42-1.47 14.2-14.7 ≥1035 ≥13.0 ≥1990 ≥25 390-422 49-53 -0.1 -0.5 180
EH

N28EH

 1.04-1.08 10.4-10.8 ≥780 ≥9.8 ≥2388 ≥30 207-231 26-29 -0.1 -0.46 200

N30EH

 1.08-1.13 10.8-11.3 ≥812 ≥10.2 ≥2388 ≥30 223-247 28-31 -0.1 -0.46 200

N33EH

 1.13-1.17 11.3-11.7 ≥820 ≥10.3 ≥2388 ≥30 248-271 31-34 -0.1 -0.46 200

N35EH

 1.17-1.22 11.7-12.2 ≥875 ≥11.0 ≥2388 ≥30 263-287 33-36 -0.1 -0.46 200

N38EH

 1.20-1.25 12.0-12.5 ≥899 ≥11.3 ≥2388 ≥30 287-310 36-39 -0.1 -0.46 200

N40EH

 1.25-1.28 12.5-12.8 ≥915 ≥11.5 ≥2388 ≥30 302-326 38-41 -0.1 -0.46 200

N42EH

 1.28-1.32 12.8-13.2 ≥970 ≥12.2 ≥2388 ≥30 318-342 40-43 -0.1 -0.46 200

N45EH

 1.32-1.36 13.2-13.6 ≥1003 ≥12.6 ≥2388 ≥30 342-366 43-46 -0.1 -0.46 200

N48EH

 1.38-1.42 13.8-14.2 ≥1031 ≥12.9 ≥2388 ≥30 366-390 46-49 -0.1 -0.46 200

N50EH

 1.39-1.44 13.9-14.4 ≥1035 ≥13.0 ≥2388 ≥30 374-406 47-51 -0.1 -0.46 200
AH

N28AH

 1.05-1.09 10.5-10.9 ≥780 ≥9.8 ≥2706 ≥34 207-231 26-29 -0.1 -0.42 220

N30AH

 1.10-1.14 11.0-11.4 ≥812 ≥10.2 ≥2706 ≥34 223-247 28-31 -0.1 -0.42 220

N33AH

 1.14-1.17 11.4-11.7 ≥812 ≥10.2 ≥2706 ≥34 247-271 31-34 -0.1 -0.42 220

N35AH

 1.17-1.22 11.7-12.2 ≥883 ≥11.1 ≥2706 ≥34 263-287 33-36 -0.1 -0.42 220

N38AH

 1.20-1.25 12.0-12.5 ≥915 ≥11.5 ≥2706 ≥34 287-310 36-39 -0.1 -0.42 220

N40AH

 1.25-1.28 12.5-12.8 ≥947 ≥11.9 ≥2706 ≥34 302-326 38-41 -0.1 -0.42 220

N42AH

 1.28-1.32 12.8-13.2 ≥970 ≥12.2 ≥2706 ≥34 318-342 40-43 -0.1 -0.42 220
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