Grades of Neodymium

The Original Online Magnet Company

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).

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INTRODUCTION TO
NEODYMIUM MAGNETS

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Applications

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characteristics of neodymium ndfeb magnets

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fea modelling services

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how magnets are made

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neodymium coatings

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neodymium magnets

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neodymium temperature ratings

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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

Example BH curve for N42 NdFeB

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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