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 designationCode
number
Maximum
BH
product
Remanent
flux
density
CoercivityCoercivityRelative
recoil
permeability
Density
(BH)maxBrHcBHcJμrecρ
kJ/m3mTkA/mkA/m-Mg/m3
N/AREFeB 170/190R7-1-117098070019001.057.5
to
7.7
N28HREFeB 210/130R7-1-221010607901300
N33MREFeB 250/120R7-1-325011308401200
N38REFeB 290/80R7-1-42901230700800
N28UHREFeB 200/190R7-1-520010607601900
N33SHREFeB 240/180R7-1-624011608401800
N38MREFeB 280/120R7-1-728012409001200
N42REFeB 320/88R7-1-83201310800880
N28EHREFeB 210/240R7-1-921010607602400
N33UHREFeB 240/200R7-1-1024011608402000
N42HREFeB 310/130R7-1-1131013009001300
N33EHREFeB 250/240R7-1-1225012008302400
N35UHREFeB 260/200R7-1-1326012108402000
N45HREFeB 340/130R7-1-1434013309201300
N45REFeB 360/90R7-1-153601350800900
N50REFeB 380/100R7-1-1638014209901000
* 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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