Technical capabilities

Magnet characteristics

Magnets have different magnetic and physical characteristics
Has a characteristic shape

What is important for the user is the "shape" of the magnet due to its magnetic characteristics.
latest《Rare earth magnet》Has the strongest residual magnetic flux density Br (related to attractive force) and coercive force bHc (related to demagnetization), so it is possible to reduce the size and flattening compared to other magnets.
Widely used before the war《Alnico magnet》Since the coercive force is small, the cross section of the magnet can be made small because the magnetic flux density between the magnetic poles is high as in rare earths (from the N pole to one side, and the shape becomes elongated for the above reasons. The advantage is stability against temperature changes. It's excellent.
《Ferrite magnet》Since the coercive force is large, the distance between the magnetic poles can be shortened.However, since the magnetic flux density is low, it is necessary to increase the cross-sectional area of ​​the magnet.Therefore, the shape is flat.

Magnetic properties and their physical properties

Typical magnet

Types of magnets rare earth Ferrite Alnico
Item unit Neodymium samarium
cobalt		 Isotropic anisotropy
dry		 anisotropy
Wet		 Alnico-5 Alnico-8
Residual magnetic flux density Br kG 12.4 10.5 2.2 3.6 4 12.7 8.8
mT 1,240 1,050 220 360 400 1,270 880
Holding force bHc kOe 11.6 8 1.9 3 3.3 0.65 1.47
kA / m 923 636 151 238 262 51 117
Maximum energy product
Bhmax		 MGOeMore 37 24 1 3 3.8 5.3 5.2
kJ / m3 294.5 191 8 23.9 30.2 42.2 41.4
Br temperature characteristics % / ℃ -0.12 -0.04 -0.18 -0.18 -0.18 -0.02 -0.01
Curie point ℃ 320 750 460 460 460 850 850
density g / cm3 7.4 8.3 4.8 4.8 4.9 7.3 7.3

BH curve of a typical magnet

rare earth

Item unit Neodymium Samarium cobalt
composition - Nd2・ Fe14・ B Sm2Co17
Molding method - Magnetic field molding Magnetic field molding
Residual magnetic flux density
Br		 mT 1210 to 1270 970 to 1020
kG 12.1 to 12.7 9.7 to 1.02
Coercive force
bHc		 kA / m 867 to 979 557 to 836
KOe 10.9 to 12.3 7 to 10.5
Coercive force
iHc		 kA / m ＞1353 716 to 1194
KOe ＞17 9 to 15
Maximum energy-product
(BH) max		 kJ / m3 278 to 310 175 to 199
MGOeMore 35 to 39 22 to 25
Temperature coefficient Br % / K -0.12 -0.04
Temperature coefficient iHc % / K -0.58 -0.03
Curie temperature
Tc		 K 593 1093
℃ 320 820
Recoil relative permeability
μrec		 - 1.05 1.05
density g / cm3 7.4 8.3
Mine strength Mpa 245 118
Kgf / mm2 25 12
Compression strength MPa 1050 500 to 519
Kgf / mm2 107 51 to 53
Tensile strength MPa 44 36
Kgf / mm2 4.5 3.6
specific heat J / (Kg ・ K) 0.50 × 103 034 × 103
cal / g ・ ℃ 0.12 0.08
硬度 HV 600 550
Coefficient of thermal expansion
〃		 ppm / K 5.5 to 7.5 8
Coefficient of thermal expansion
⊥		 ppm / K -3 ~ 0.5 11
JIS - REFe280 / 120 RECo160 / 70
MMPA - - -
Required magnetic field kA / m 2400 1990
KOe 30 25
Electrical resistivity nΩ ・ m 1.3 × 10-4 0.8 to 0.9

Ferrite

Item unit Isotropic Dry anisotropy Wet anisotropy
composition - BaO ・ XNUMXFeTwoO3 SrO ・ XNUMXFe2O3 SrO ・ XNUMXFe2O3
Molding method - Dry molding Dry magnetic field molding Wet magnetic field molding
Residual magnetic flux density
Br		 mT ≧ 200 310 to 360 380 to 400
kG ≧ 2.0 3.1 to 3.6 3.8 to 4.0
Coercive force
bHc		 kA / m 127 to 159 220 to 250 230 to 275
KOe 1.6 to 2.0 2.8 to 3.2 2.9 to 3.5
Coercive force
iHc		 kA / m 135 to 167 280 to 320 235 to 290
KOe 1.7 to 2.1 3.5 to 4.0 3.0 to 3.7
Maximum energy-product
(BH) max		 kJ / m3 6.3 to 9.5 20 to 24 27 to 32
MGOeMore 0.8 to 1.2 2.5 to 3.0 3.4 to 4.1
Temperature coefficient Br % / K -0.18 -0.18 -0.18
Temperature coefficient iHc % / K 0.22 0.27 to 0.42 0.27 to 0.42
Curie temperature
Tc		 K 723 733 733
℃ 450 460 460
Recoil relative permeability
μrec		 - 1.1 to 1.2 1.1 to 1.2 1.05 to 1.1
density g / cm3 4.8 4.9 4.9
Mine strength Mpa 29 to 68 49 to 88 49 to 88
Kgf / mm2 3 to 7 5 to 9 5 to 9
Compression strength MPa ＞686 ＞686 ＞686
Kgf / mm2 ＞70 ＞70 ＞70
Tensile strength MPa 19 to 49 19 to 49 19 to 49
Kgf / mm2 2 to 5 2 to 5 2 to 5
specific heat J / (Kg ・ K) 0.84 × 103 0.84 × 103 0.84 × 103
cal / g ・ ℃ 0.2 0.2 0.2
硬度 HV 530 530 530
Coefficient of thermal expansion
〃		 ppm / K 9.9 11 13
Coefficient of thermal expansion
⊥		 ppm / K 9.9 9 8
JIS - MPB-8 / 15D MPS-24 / 24D MPS-31 / 24W
MMPA - CERAMIC-1 CERAMIC-6 CERAMIC-8
Required magnetic field kA / m 800 800 800
KOe 10 10 10
Electrical resistivity nΩ ・ m ＞102 ＞102 ＞102

Alnico

Item unit Arnico XNUMX Arnico XNUMX Sintered alnico
composition - 8Al-14Ni-24Co-3Cu-Remaining Fe 7Al-15Ni-34Co-4Cu-Remaining Fe 8Al-14Ni-24Co-3Cu-Remaining Fe
Molding method - casting casting Wet magnetic field molding
Residual magnetic flux density
Br		 mT 1250 to 1300 830 to 900 1150
kG 12.5 to 13 8.3 to 9.0 11.5
Coercive force
bHc		 kA / m 47.7 to 52.5 110 to 123 50
KOe 0.60 to 0.66 1.38 to 1.55 0.63
Coercive force
iHc		 kA / m - - -
KOe
Maximum energy-product
(BH) max		 kJ / mm3 38.2 to 43.8 38.2 to 43.0 37
MGOeMore 4.8 to 5.5 4.8 to 5.4 4.6
Temperature coefficient Br % / K -0.02 -0.02 -0.02
Temperature coefficient iHc % / K - - -
Curie temperature
Tc		 K 1123 1123 1123
℃ 850 850 850
Recoil Permeability μrec - 3.6 3.6 3.6
density g / cm3 7.3 7.3 7.1
Mine strength Mpa 73.5 73.5 7.35
Kgf / mm2 7.5 7.5 7.5
Compression strength MPa - - -
Kgf / mm2
Tensile strength MPa 37.2 37.2 37.3
Kgf / mm2 3.8 3.8 3.8
specific heat J / (Kg ・ K) - - -
cal / g ・ ℃
硬度 HV 650 650 650
Coefficient of thermal expansion
〃		 ppm / K 11 11 11
Coefficient of thermal expansion
⊥		 ppm / K 11 11 11
JIS - AlNiCo37 / 5 AlNiCo38 / 11 AlNiCo S-34 / 5
MMPA - AlNiCO-5 AlNiCO-8 -
Required magnetic field kA / m 240 640 240
KOe 3.0 8.0 3.0
Electrical resistivity nΩ ・ m 4.7 × 102 4.7 × 102 47 × 102

Others

Item unit Neojibond Rubber anisotropy Rubber isotropic
composition - Nd2・ Fe14・ B - -
Molding method - Compression molding injection molding Roll molding Roll molding
Residual magnetic flux density
Br		 mT 640 to 710 640 to 710 230 1370
kG 6.4 to 7.1 6.4 to 7.1 2.3 1.37
Coercive force
bHc		 kA / m 570 to 760 410 to 620 135 102
KOe 5.7 to 7.6 4.1 to 6.2 1.7 1.28
Coercive force
iHc		 kA / m 370 to 470 250 to 400 - -
KOe 4.7 to 5.9 3.1 to 4.9
Maximum energy-product
(BH) max		 kJ / m3 60 to 96 28 to 60 8.8 4.0
MGOeMore 7.5 to 12.0 3.5 to 7.5 1.1 0.5
Temperature coefficient Br % / K -0.1 to -0.15 -0.1 to -0.15 -0.18 to -0.19 -0.18
Temperature coefficient iHc % / K - - 0.35 to 0.5 0.35
Curie temperature
Tc		 K ※ 393 ※ 393 ※ 353 ※ 353
℃ ※ 120 ※ 120 ※ 80 ※ 80
Recoil relative permeability
μrec		 - 1.1 to 1.2 1.1 to 1.2 1.03 to 1.07 1.03 to 1.07
density g / cm3 5.6 to 6.2 4.2 to 5.5 3.7 3.7
Mine strength Mpa 49.0 to 58.8 - - -
Kgf / mm3 5.0 to 6.0
Compression strength MPa - - - -
Kgf / mm3
Tensile strength MPa - 30000 666 392
Kgf / mm3 3061 68 40
specific heat J / (Kg ・ K) - - 0.7-0.8 × 103 0.7-0.8 × 103
cal / g ・ ℃ 0.167 to 0.191 0.167 to 0.191
硬度 HV 430 430 760 450
Coefficient of thermal expansion
〃		 ppm / K 13 to 15 50 - -
Coefficient of thermal expansion
⊥		 ppm / K 13 to 15 50 100 to 150 100 to 150
JIS - REFe63 / 64p REFe63 / 64p - -
MMPA - - - - -
Required magnetic field kA / m 2000 2000 800 800
KOe 25 25 10 10
Electrical resistivity nΩ ・ m 56 × 103 56 × 103 - -