china sintered ndfeb magnets neodymium magnets manufacturer & supplierSintered NdFeB magnets, i.e. sintered neodymium iron boron magnets, are those permanent magnetic materials that based on a Nd-Fe-B tetragonal crystal structure, and they are manufactured through a powder metallurgy (PM) process. They contain three basic elements neodymium, iron and boron. The neodymium element can be substituted by a portion of other rare earth elements (REEs) including praseodymium (Pr), dysprosium (Dy), terbium (Tb), cerium (Ce), etc. The iron element can be substituted by a portion of cobalt (Co) element to increase the magnets’ Curie temperature (Tc), thermal stability and corrosion resistance. In order to control the microstructure and the microchemistry so as to meet required performance, it also adds a small portion of other metal elements including aluminium (Al), copper (Cu), niobium (Nb), gallium (Ga), etc. Almost at the same time in the early 1980s, NdFeB magnets were invented by M. Sagawa’s and J. J. Croat’s teams through a powder metallurgical process and a melt-spinning technique, respectively. Due to their outstanding magnetic properties (high remanence Br: 1.1-1.5 T, middle high coercivity Hcj: 800-3000 kA/m3 and high maximum energy product (BH)max: 220-430 kJ/m3) together with competitive cost, sintered NdFeB magnets are widely applied in direct current (DC) motors, servo motors, stepper/stepping motors, synchronous motors, linear motors, voice coil motors (VCMs), wind turbines and generators, magnetic resonance imaging (MRI), electric power steering (EPS), magnetic separation, etc.

Sintered NdFeB Magnets’ Grades and Their Magnetic Properties

GradeBrHcbHcj(BH)maxTw
kGsTkOekA/mkOekA/mMGOekJ/m3ºC
N5214.2-14.81.42-1.48≥10.5≥836≥11≥87650-53398-422≤80
N5013.9-14.41.39-1.44≥10.8≥859≥12≥95548-51382-406
N4813.6-14.11.36-1.41≥11.6≥92346-49366-390
N4513.2-13.71.32-1.37≥11.6≥92343-46342-366
N4212.8-13.31.28-1.33≥11.4≥90740-43318-342
N4012.4-12.91.24-1.29≥11.4≥90738-41302-326
N3812.1-12.61.21-1.26≥11.2≥89136-39286-310
N3511.7-12.21.17-1.22≥10.8≥85933-36263-286
N3311.3-11.81.13-1.18≥10.5≥83631-34247-271
N3010.8-11.31.08-1.13≥10.0≥79628-31223-247
N50M13.9-14.41.39-1.44≥13.0≥1035≥13≥103548-51382-406≤100
N48M13.6-14.11.36-1.41≥12.8≥1019≥14≥111446-49366-390
N45M13.2-13.71.32-1.37≥12.5≥99543-46342-366
N42M12.8-13.31.28-1.33≥12.0≥95540-43318-342
N40M12.4-12.91.24-1.29≥11.6≥92338-41302-326
N38M12.1-12.61.21-1.26≥11.3≥89936-39286-310
N35M11.7-12.21.17-1.22≥10.9≥86733-36263-286
N33M11.3-11.81.13-1.18≥10.5≥83631-34247-271
N30M10.8-11.31.08-1.13≥10.0≥79628-31223-247
N50H13.9-14.41.39-1.44≥13.0≥1035≥16≥127348-51382-406≤120
N48H13.6-14.11.36-1.41≥12.8≥1019≥17≥135346-49366-390
N45H13.2-13.71.32-1.37≥12.5≥99543-46342-366
N42H12.8-13.31.28-1.33≥12.0≥95540-43318-342
N40H12.4-12.91.24-1.29≥11.6≥92338-41302-326
N38H12.1-12.61.21-1.26≥11.3≥89936-39286-310
N35H11.7-12.21.17-1.22≥10.9≥86733-36263-286
N33H11.3-11.81.13-1.18≥10.5≥83631-34247-271
N30H10.8-11.31.08-1.13≥10.0≥79628-31223-247
N48SH13.6-14.11.36-1.41≥12.8≥1019≥20≥159246-49366-390≤150
N45SH13.2-13.71.32-1.37≥12.5≥99543-46342-366
N42SH12.8-13.31.28-1.33≥12.0≥95540-43318-342
N40SH12.4-12.91.24-1.29≥11.6≥92338-41302-326
N38SH12.1-12.61.21-1.26≥11.3≥89936-39286-310
N35SH11.7-12.21.17-1.22≥10.9≥86733-36263-286
N33SH11.3-11.81.13-1.18≥10.5≥83631-34247-271
N30SH10.8-11.31.08-1.13≥10.0≥79628-31223-247
N42UH12.8-13.31.28-1.33≥12.2≥971≥25≥199040-43318-342≤180
N40UH12.4-12.91.24-1.29≥11.8≥93938-41302-326
N38UH12.1-12.61.21-1.26≥11.5≥91536-39286-310
N35UH11.7-12.21.17-1.22≥11.1≥88333-36263-286
N33UH11.3-11.81.13-1.18≥10.7≥85131-34247-271
N30UH10.8-11.31.08-1.13≥10.2≥81228-31223-247
N40EH12.4-12.91.24-1.29≥11.8≥939≥30≥238838-41302-326≤200
N38EH12.1-12.61.21-1.26≥11.5≥91536-39286-310
N35EH11.7-12.21.17-1.22≥11.1≥88333-36263-286
N33EH11.3-11.81.13-1.18≥10.7≥85131-34247-271
N30EH10.8-11.31.08-1.13≥10.2≥81228-31223-247
N35AH11.7-12.21.17-1.22≥11.1≥883≥35≥278633-36263-286≤230
N33AH11.3-11.81.13-1.18≥10.7≥85131-34247-271
N30AH10.8-11.31.08-1.13≥10.2≥81228-31223-247
N28AH10.4-10.91.04-1.09≥9.8≥78026-29207-231

Note:
∗ The data in the above table were samples’ results tested at the temperature of 20 °C.
∗ The temperature coefficients of Br and Hcj are α(Br): -0.09~-0.12 %/ºC and β(Hcj): -0.40~-0.60 %/ºC, respectively.
∗ The above data are only for reference, magnets can be tailored according to customers’ personalized requirements.

Sintered NdFeB Magnets’ Shapes, Magnetization Direction and Size Range

ShapeGraphic DescriptionMagnetization DirectionSize Range
Disc/Cylinder Magnetcustom disc neodymium magnets size diagramdisc magnet pole, Disc permanent magnets Axially MagnetizedAxially MagnetizedD: 1-100 mm
T: 0.5-100 mm
disc magnet pole, Disc permanent magnets Diametrically MagnetizedDiametrically MagnetizedD: 1-100 mm
T: 0.5-100 mm
Ring Magnetcustom ring neodymium magnets size diagramring magnet pole, ring permanent magnets Axially MagnetizedAxially MagnetizedOD: 4-100 mm
ID: 1-90 mm
T: 1-60 mm
ring magnet pole, ring permanent magnets Diametrically MagnetizedDiametrically MagnetizedOD: 4-100 mm
ID: 1-90 mm
T: 1-60 mm
ring magnet pole, ring permanent magnets Radially MagnetizedRadially MagnetizedOD: 24-200 mm
ID: 18-180 mm
T: 5-60 mm
Block/Rectangular Magnetcustom block neodymium magnets size diagramblock permanent magnets Thickness MagnetizedThickness MagnetizedL: 1-160 mm
W: 1-100 mm
T: 1-100 mm
Arc/Segment Magnetcustom arc neodymium magnets size diagramarc segment permanent magnets Diametrically magnetizationDiametrically MagnetizedOD-ID≥1 mm
L: 1-160 mm
W: 3-100 mm
H: 1-80 mm

Note:
∗ Other shapes of sintered NdFeB magnets can also be tailored according to customers’ specific requirements.

Sintered NdFeB Magnets' Coatings

CoatingThickness (μm)SST (hr)PCT (hr)Tw (ºC)
Zn (Zinc)5-15>24-≤160
C-Zn (Colored Zinc)5-15>48-≤160
Electroless Nickel10-30>96>72≤230
NiCuNi (Nickel Copper Nickel)10-20>48>48≤230
NiCu + Black Nickel10-20>48>72≤230
NiCuNi + Tin10-25>48>48≤160
NiCuNi + Gold10-25>48>48≤230
NiCuNi + Silver10-25>48>48≤160
Epoxy10-30>72>48≤160
Teflon10-20>48-≤230
Everlube10-20>96>72≤230
Parylene0.2-5>96-≤230

Note:
∗ Salt spray test (SST) was conducted at 35 ºC with 5% NaCl solution.
∗ Pressure cooker test (PCT) was conducted at 120 ºC, 2 atm and 100% RH.

Some Physical Properties of Sintered NdFeB Magnets

ParameterUnitValue
Density (ρ)g/cm37.4-7.7
Curie Temperature (Tc)ºC310-370
Recoil Permeability (μrec)-1.05
Vickers Hardness (HV)MPa500-600
Bending Strength (σbb)MPa200-400
Compressive Strenght (σbc)MPa1000-1100
Tensile Strength (σb)MPa80-90
Resistivity (ρ)μΩ·m1.4-1.6
Thermal Conductivity (λ)W/(m·K)8-10
Young's Modulus (E)GPa150-200
Thermal Expansivity ∥ Magnetization (α)10-6/ºC3-4
Thermal Expansivity ⊥ Magnetization (α)10-6/ºC1-3

Note:
∗ The above data are only for reference, specific magnets maybe have different values.