Grades of Neodymium

The Neodymium magnets have a simple nomenclature. They all start with "N" which simply stands for "Neo" (industry simplification of Neodymium) and is followed by a two digit number.

This number represents the maximum energy product in Mega-Gauss Oersteds (MGOe) where 1MGOe (cgs units) equals 7958kJ/m3 (SI units). The range available used to be N24 up to N52. The lower grades are no longer made and the range now starts at around N30 or N33. N50 is the highest readily available grade. N52 is possible but only in certain sizes. Although the maximum possible energy product is calculated in to be N64, it is unlikely such high strengths of Neodymium will be achievable in the near future (when the newest grades are commercially available they are often available only for direct sale into military applications).

A suffix letter (or two letters) may then follow the number. It is stated that these letters (or lack of) relate to a temperature rating. Strictly speaking this is not correct. The letters actually indicate the Intrinsic Coercivity (Hci) of the material. The higher the Hci, the higher the temperature the Neodymium magnet material can be exposed to before the magnet will start to show permanent losses in output. It is this fact that is used to link the last letter(s) to a temperature rating.

The current range of Neodymium Iron Boron magnets is as follows:-

N27, N30, N33, N35, N38, N40, N42, N45, N48, N50, N52, N30M, N33M, N35M, N38M, N40M, N42M, N45M, N48M, N50M, N30H, N33H, N35H, N38H, N40H, N42H, N45H, N48H, N30SH, N33SH, N35SH, N38SH, N40SH, N42SH, N45SH, N28UH, N30UH, N33UH, N35UH, N38UH, N40UH, N28EH, N30EH, N33EH, N35EH, N38EH, N33VH/AH.

However, the temperature rating for Neodymium is merely a guide value. It is the physical size and shape of the NdFeB magnet and the total magnetic circuit that actually determines how well a magnet will perform at raised temperature. For example a NdFeB magnet in free space will demagnetise at a lower temperature than the same sized NdFeB magnet connected to a piece of mild steel. It will also demagnetise at a lower temperature than a NdFeB magnet of twice the length in the direction of magnetisation. The Intrinsic curve shape also plays a part in the temperature performance of NdFeB.

The total magnetic circuit that the Neodymium magnet is in determines its working point on the Intrinsic curve. By having a higher working point (e.g. magnet connected to mild steel or a longer magnet) the magnet will cope with a higher temperature before it will show signs of demagnetisation (when the working point passes the ‘knee’ of the Intrinsic curve). The situation is made more unclear if an external demagnetising field is present as this may mean the Neodymium magnet may demagnetise at even lower temperatures. Therefore, it is quickly apparent that the total magnetic circuit, the total environment and the application as a whole must all be reviewed to determine whether a Neodymium magnet will still perform at a satisfactory level towards the recommended maximum working temperature as indicated by the letter(s) in its NdFeB grade classification. For example, a magnet rated for a recommended maximum working temperature of 150 degrees C may start to demagnetise significantly at 100 degrees C is the design is poor or a magnet rated for a recommended maximum working temperature of 80 degrees C may start to demagnetise significantly at 100 degrees C is the design is really good.

The recommended maximum working temperatures are indicators of likely performance but the user should review their design for suitability or contact us for design assistance. The letter nomenclature is as follows (where xx is the Maximum Energy Product in MGOe):-

Nxx 12000 Oe / 955kA/m (minimum)80 deg C / 175 deg F suggested maximum
NxxM 14000 Oe / 1115kA/m (minimum) 100 deg C / 212 deg F suggested maximum
NxxH 17000 Oe / 1355kA/m (minimum) 120 deg C / 248 deg F suggested maximum
NxxSH 20000 Oe / 1590kA/m (minimum) 150 deg C / 302 deg F suggested maximum
NxxUH 25000 Oe / 1990kA/m (minimum) 180 deg C / 356 deg F suggested maximum
NxxEH 30000 Oe / 2385kA/m (minimum) 200 deg C / 392 deg F suggested maximum
NxxVH / NxxAH 35000 Oe / 2785kA/m (minimum) 230 deg C / 446 deg F suggested maximum

Grades of Neodymium

Nomenclature of NdFeB grades

Chinese Standard - commonly used globally, especially in EU

Minimum Values

Material

Br

Hcb (Hc)

Hcj (Hci)

(BH)max

mT

G

kA/m

Oe

kA/m

mT

G

kA/m

N27

 

1,030

10,300

796

10,000

955

12,000

119

25

N30

 

1,080

10,800

796

10,000

955

12,000

223

28

N33

 

1,130

11,300

836

10,500

955

12,000

247

31

N35

 

1,170

11,700

868

10,900

955

12,000

263

33

N38

 

1,220

12,200

899

11,300

955

12,000

287

36

N40

 

1,250

12,500

907

11,400

955

12,000

302

38

N42

 

1,280

12,800

915

11,500

955

12,000

318

40

N45

 

1,320

13,200

923

11,600

955

12,000

342

43

N48

 

1,380

13,800

923

11,600

955

12,000

366

46

N50

 

1,400

14,000

796

10,000

876

11,000

382

48

N52

 

1,430

14,300

796

10,000

876

11,000

398

50

N30

M

1,080

10,800

796

10,000

1,115

14,000

223

28

N33

M

1,130

11,300

836

10,500

1,115

14,000

247

31

N35

M

1,170

11,700

868

10,900

1,115

14,000

263

33

N38

M

1,220

12,200

899

11,300

1,115

14,000

286

36

N40

M

1,250

12,500

923

11,600

1,115

14,000

302

38

N42

M

1,280

12,800

955

12,000

1,115

14,000

318

40

N45

M

1,320

13,200

995

12,500

1,115

14,000

342

43

N48

M

1,380

13,800

1,027

12,900

1,115

14,000

366

46

N50

M

1,400

14,000

1,033

13,000

1,115

14,000

382

48

N30

H

1,080

10,800

796

10,000

1,355

17,000

223

28

N33

H

1,130

11,300

836

10,500

1,355

17,000

247

31

N35

H

1,170

11,700

868

10,900

1,355

17,000

263

33

N38

H

1,220

12,200

899

11,300

1,355

17,000

286

36

N40

H

1,250

12,500

923

11,600

1,355

17,000

302

38

N42

H

1,280

12,800

955

12,000

1,355

17,000

318

40

N45

H

1,320

13,200

955

12,000

1,355

17,000

342

43

N48

H

1,370

13,700

995

12,500

1,355

17,000

366

46

N30

SH

1,080

10,800

804

10,100

1,590

20,000

223

28

N33

SH

1,130

11,300

844

10,600

1,590

20,000

247

31

N35

SH

1,170

11,700

876

11,000

1,590

20,000

263

33

N38

SH

1,220

12,200

907

11,400

1,590

20,000

286

36

N40

SH

1,250

12,500

939

11,800

1,590

20,000

302

38

N42

SH

1,280

12,800

987

12,400

1,590

20,000

318

40

N45

SH

1,320

13,200

1,003

12,600

1,590

20,000

342

43

N28

UH

1,020

10,200

764

9,600

1,990

25,000

207

26

N30

UH

1,080

10,800

812

10,200

1,990

25,000

223

28

N33

UH

1,130

11,300

852

10,700

1,990

25,000

247

31

N35

UH

1,180

11,800

860

10,800

1,990

25,000

263

33

N38

UH

1,220

12,200

899

11,300

1,990

25,000

287

36

N40

UH

1,250

12,500

899

11,300

1,990

25,000

302

38

N28

EH

1,040

10,400

780

9,800

2,385

30,000

207

26

N30

EH

1,080

10,800

812

10,200

2,385

30,000

223

28

N33

EH

1,140

11,400

836

10,500

2,385

30,000

247

31

N35

EH

1,170

11,700

876

11,000

2,385

30,000

263

33

N38

EH

1,220

12,200

899

11,300

2,385

30,000

287

36

N33

VH / AH

1,130

11,300

836

10,500

2,706

34,000

239

30

American Standard

Typical Values

Material

Br

Hcb (Hc)

Hcj (Hci)

(BH)max

mT

G

kA/m

Oe

kA/m

Oe

kJ/m3

MGOe

24/41

1,000

10,000

764

9,600

3,263

41,000

190

24.0

26/32

1,050

10,500

803

10,090

2,507

31,500

205

26.0

28/23

1,050

10,500

820

10,300

1,830

23,000

225

28.0

28/32

1,073

10,730

835

10,490

2,507

31,500

225

28.0

30/19

1,130

11,300

859

10,800

1,512

19,000

240

30.0

30/27

1,130

11,300

859

10,800

2,149

27,000

240

30.0

32/16

1,180

11,800

891

11,200

1,273

16,000

255

32.0

32/31

1,160

11,600

883

11,100

2,467

31,000

255

32.0

34/22

1,196

11,960

915

11,500

1,771

22,250

270

34.0

36/19

1,231

12,310

917

11,520

1,523

19,140

285

36.0

36/26

1,220

12,200

931

11,700

2,069

26,000

285

36.0

38/15

1,250

12,500

955

12,000

1,194

15,000

300

38.0

38/23

1,240

12,400

955

12,000

1,830

23,000

300

38.0

40/15

1,280

12,800

955

12,000

1,194

15,000

320

40.0

40/23

1,290

12,900

987

12,400

1,830

23,000

320

40.0

42/15

1,310

13,100

1,011

12,700

1,194

15,000

335

42.0

44/15

1,350

13,500

1,035

13,000

1,194

15,000

350

44.0

48/11

1,375

13,750

820

10,300

875

11,000

380

48.0

50/11

1,410

14,100

820

10,300

875

11,000

400

50.0

European Standard (IEC 60404-8-1)

Minimum Values

Material

Group code

Br

Hcb (Hc)

Hcj (Hci)

(BH)max

mT

kG

kA/m

kOe

kA/m

kOe

kJ/m3

MGOe

170/190

R7-1-1

980

9800

700

8795

1900

23875

170

21.4

210/130

R7-1-2

1060

10600

790

9925

1300

16335

210

26.4

250/120

R7-1-3

1130

11300

840

10555

1200

15080

250

31.4

290/80

R7-1-4

1230

12300

700

8795

800

10055

290

36.4

200/190

R7-1-5

1060

10600

760

9550

1900

23875

200

25.1

240/180

R7-1-6

1160

11600

840

10555

1800

22620

240

30.2

280/120

R7-1-7

1240

12400

900

11310

1200

15080

280

35.2

320/88

R7-1-8

1310

13100

800

10055

880

11060

320

40.2

210/240

R7-1-9

1060

10600

760

9550

2400

30160

210

26.4

240/200

R7-1-10

1160

11600

840

10555

2000

25130

240

30.2

310/130

R7-1-11

1300

13000

900

11310

1300

16335

310

39.0

250/240

R7-1-12

1200

12000

830

10430

2400

30160

250

31.4

260/200

R7-1-13

1210

12100

840

10555

2000

25130

260

32.7

340/130

R7-1-14

1330

13300

920

11560

1300

16335

340

42.7

360/90

R7-1-15

1350

13500

800

10055

900

11310

360

45.2

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