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Characteristics of NdFeB Magnets

Summary of Neodymium Iron Boron Physical Properties (NdFeB) magnets

A neodymium magnet (also known as NdFeB, NIB or Neo magnet) is a permanent magnet made from an alloy of neodymium, iron, and boron to form the Nd2Fe14B tetragonal crystalline structure.They are the most widely used type of rare-earth magnet.

ItemsParametersUnitReference Range
Regular Physical PropertiesDensity / ρg/cm37.40-7.80
Vickness Hardness / HV–550-650
Electrical PropertiesElectrical ResistivityμΩ·m1.4
Mechanical PropertiesCompressive StrengthMPa1050
Tensile StrengthMPa80
Bending StrengthMPa290
Thermal PropertiesThermal ConductivityW/(m·K)6-8
Coefficient of Thermal Expansion10-6/KC⊥: -1.5, C∥: 6.5.
Magnetic properties

There are eight different standard grades of neodymium magnets typically used in commercial applications today ranging from N35 to N52. Neodymium magnets are graded by their maximum energy product (BH)max with N52 grade neodymium providing the greatest magnetic performance and N35 being the weakest. The magnetic properties of the various grades of neodymium magnets are adjusted by using varying amounts of rare earth elements in the alloy mixture, with each element adjusting the characteristics of the material in a different way. Below, you can see the list of standard neodymium magnet grades and their magnetic properties below.

GradeRemanenceCoercive ForceIntrinsic Coercive ForceMax. energy productMax. Operating Temperature
BRHcBHcj(BH)max
mTkA/mkA/mMGOe
N351180-1240≥10.94≥1233-3680°C
N381220-1260≥11.31≥1236-4080°C
N401260-1300≥11.40≥1238-4280°C
N421300-1320≥11.40≥1240-4480°C
N451330-1380≥11.40≥1242-4680°C
N481370-1420≥11.40≥1245-4980°C
N501410-1440≥10.50≥1248-5180°C
N521430-1460≥10.50≥1150-5380°C
N33M1140-1170≥10.65≥1430-35100°C
N35M1180-1220≥10.94≥1433-36100°C
N38M1220-1260≥11.4≥1436-40100°C
N40M1260-1300≥11.78≥1438-42100°C
N42M1300-1320≥12.14≥1440-44100°C
N45M1330-1380≥12.43≥1442-46100°C
N48M1370-1430≥12.80≥1445-49100°C
N50M1410-1440≥13.1≥1447-51100°C
N52M1430-1460≥13.1≥1450-53100°C
N30H1080-1120≥10.14≥1728-31120°C
N33H1140-1180≥10.70≥1731-35120°C
N35H1180-1220≥11≥1733-37120°C
N38H1220-1260≥11.46≥1736-40120°C
N40H1260-1300≥11.83≥1738-42120°C
N42H1300-1320≥12.21≥1740-44120°C
N45H1320-1360≥12≥1742-46120°C
N48H1370-1420≥12.86≥1746-49120°C
N50H1410-1440≥13.24≥1748-52120°C
N52H1420-1460≥12.8≥1750-54120°C
N30SH1110-1140≥10.18≥2028-32150°C
N33SH1140-1180≥10.75≥2031-35150°C
N35SH1180-1220≥11≥2033-36150°C
N38SH1220-1260≥11.5≥2036-40150°C
N40SH1260-1300≥11.88≥2038-42150°C
N42SH1300-1320≥12.26≥2040-44150°C
N45SH1320-1360≥11.5≥2042-46150°C
N48SH1370-1400≥12.85≥2044-47150°C
N50SH1410-1440≥11.5≥2046-49150°C
N28UH1040-1100≥9.86≥2526-30180°C
N30UH1100-1140≥10.24≥2528-32180°C
N33UH1140-1180≥10.8≥2531-35180°C
N35UH1180-1220≥11.09≥2533-36180°C
N38UH1220-1260≥11.54≥2536-44180°C
N40UH1260-1300≥11.94≥2538-42180°C
N42UH1300-1320≥12.32≥2540-44180°C
N45UH1320-1360≥11≥3042-46180°C
N28EH1180-1240≥10.3≥3026-30200°C
N30EH1180-1240≥10.6≥3028-32200°C
N33EH1180-1240≥10.8≥3031-35200°C
N35EH1180-1240≥11.09≥3033-36200°C
N38EH1180-1240≥11.54≥3036-40200°C
N30AH1180-1240≥10.24≥3528-32230°C
N33AH1180-1240≥10.80≥3530-35230°C
N35AH1180-1240≥10.7≥3532-36230°C
Table comparing main NdFeB coating types

CoatingThickness(μm)ColorSST(hrs)PCT(hrs)Characteristics
BW-Zn4-15Bright blue≥24–Secondly commonly used single layer coating. Poor corrosion resistance.
Color-Zn4-15Shining color≥48–Corrosion resistance is better than BW-Zn.
Ni-Cu-Ni5-20Bright silver≥48≥48Most regular used multi-layer coating. Excellent humidity and salt spray resistance.
Electroless Ni5-20Dark silver≥72≥48Excellent humidity and salt spray resistance with uniform appearance.
Ni-Cu-Ni-Au5-20Golden≥72≥96Excellent electrical conductivity and decorative performance.
Ni-Cu-Ni-Ag5-20Silver≥72≥96Excellent electrical conductivity and decorative performance.
Ni-Cu-Ni-Sn5-20Silver≥72≥96Excellent humidity resistance.
Phosphate1-3Dark grey––Temporary protection.
Aluminum2-15Bright silver≥24≥24Noticeable coating.
Epoxy resin10-30Black/Grey≥72≥72Excellent humidity and salt spray resistance. Superir binding force.
Parylene5-20Colorless≥96–Excellent humidity, salt spray, corrosive vapors, and solvents resistance. Free of pore.
Everlube10-15Golden yellow≥120≥72Excellent humidity resistance.
Teflon8-15Black≥24≥24High temperature and rub resistance. Self-lubricant and 100% water-proof.

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