NdFeB Magnet Grades

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The NdFeB magnet grades nomenclature is simple.

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 NdFeB magnet 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 NbFeB grades are commercially available they are often available only for direct sale into military applications).

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A suffix letter (or two letters) may then follow the number. It is stated that these letters (or lack of them) 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.

NdFeB Magnet Grades References

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 a 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 magnet 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 if 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 if the design is really good.

NdFeB Working Temperatures

The recommended NdFeB magnets' 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

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Nomenclature of NdFeB Magnet Grades

Chinese Standard - commonly used globally, especially in EU
Minimum Values
Material		Br		Hcb (Hc)		Hcj (Hci)		(BH)max
Material		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
Material	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
Material	Group code	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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NdFeB Magnet Grades

The NdFeB magnet grades nomenclature is simple.

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

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