IEC Standard for Rare earth-iron-boron (REFeB) Magnets

The International Electrotechnical Commission (IEC) published the standard IEC 60404-8-1:2015 for magnetically hard materials (permanent magnets). In this standard, the part of Rare earth-iron-boron (REFeB) magnets’ magnetic properties and densities is shown in the table below.

In the REFeB magnets, the RE element is mainly neodymium (Nd), and the manufacturing method is a powder sintering process, so REFeB magnets are also known as sintered NdFeB magnets. China supplies most of the sintered NdFeB magnets in the global market, for those overseas customers using the IEC standard, it is necessary to compare the Chinese standard with the IEC standard. In the left column of the table, it lists some China grades of sintered NdFeB magnets, which are identical with IEC standard for REFeB magnets.

China
grade e+
Magnetic properties and densities of REFeB magnets (IEC 60404-8-1:2015)
Brief designation Code
number
Maximum
BH
product
Remanent
flux
density
Coercivity Coercivity Relative
recoil
permeability
Density
(BH)max Br HcB HcJ μrec ρ
kJ/m3 mT kA/m kA/m - Mg/m3
N/A REFeB 170/190 R7-1-1 170 980 700 1900 1.05 7.5
to
7.7
N28H REFeB 210/130 R7-1-2 210 1060 790 1300
N33M REFeB 250/120 R7-1-3 250 1130 840 1200
N38 REFeB 290/80 R7-1-4 290 1230 700 800
N28UH REFeB 200/190 R7-1-5 200 1060 760 1900
N33SH REFeB 240/180 R7-1-6 240 1160 840 1800
N38M REFeB 280/120 R7-1-7 280 1240 900 1200
N42 REFeB 320/88 R7-1-8 320 1310 800 880
N28EH REFeB 210/240 R7-1-9 210 1060 760 2400
N33UH REFeB 240/200 R7-1-10 240 1160 840 2000
N42H REFeB 310/130 R7-1-11 310 1300 900 1300
N33EH REFeB 250/240 R7-1-12 250 1200 830 2400
N35UH REFeB 260/200 R7-1-13 260 1210 840 2000
N45H REFeB 340/130 R7-1-14 340 1330 920 1300
N45 REFeB 360/90 R7-1-15 360 1350 800 900
N50 REFeB 380/100 R7-1-16 380 1420 990 1000
* e+ = equal
or superior
Typical values of the parameters:
Temperature coefficient of remanence α(Br) = -0.1 %/°C to -0.12 %/°C (for 20 °C to 100 °C)
Temperature coefficient of coercivity α(HcJ) = -0.45 %/°C to -0.6 %/°C (for 20 °C to 100 °C)
Curie temperature: 310 °C
Maximum opertating temperature: 200 °C

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