Hard Ferrite Magnets
Product Description
General Information
Ferrite Magnets are sintered Permanent Magnets composed of Barium or
Strontium Ferrite. This class of magnets, aside from good resistance to
demagnetization, has the popular advantage of low cost.
Ferrite magnets are very hard and brittle, and require
specialized machining techniques. Moreover, they should be machined in
an unmagnetized state. We are equipped to machine these materials to
specifications.
Anisotropic grades are oriented in the manufacturing direction, and
must be magnetized in the direction of orientation. Isotropic grades are
not oriented and can be magnetized in any direction, although some
degree of greater magnetic strength will be found in the pressing
dimension, usually the shortest dimension.
Due to their low cost,
Ferrite magnets enjoy a very
wide range of applications, from motors and loudspeakers to toys and
crafts, and are the most widely used permanent magnets today.
Pressing and sintering involves pressing very fine ferrite powder in a
die, and then sintering this pressed magnet. All fully dense Ferrite
magnets are produced this way. Ferrite magnets can be wet pressed or dry
pressed. Wet pressing yields better magnetic properties, but poorer
physical tolerances. Generally, the powder is dry for grade 1 or 5
materials, and wet for grade 8 and higher materials. Sintering involves
subjecting the material to high temperatures to fuse the pressed powder
together, thus creating a solid material. Magnets produced through this
process usually need to have some finish machining, otherwise surface
finishes and tolerances are not acceptable. Some manufacturers extrude
instead of press wet powder slurry and then sinter the material. This is
sometimes done for arc segment shapes, where the arc cross-section is
extruded in long lengths, sintered, and then cut to length.
Assemblies
We are able to manufacture metal and other components of finished sub assemblies using our CNC machining facilities.
Assemblies using metal or other components and magnets can be
fabricated by adhering magnets with adhesives to suit a range of
environments, by mechanically fastening magnets, or by a combination of
these methods. Due to the relatively brittle nature of these magnet
materials, press fits are not recommended.
Surface Treatments
The corrosion resistance of Ferrite is considered excellent , and no
surface treatments are required. However, Ferrite magnets may have a
thin film of fine magnet powder on the surface and for clean,
non-contaminated applications, some form of coating may be required.
Magnetizing and Handling
Ferrite magnets require magnetizing fields of about 10 kOe. They can be
magnetized with multiple poles on one or both pole surfaces. No special
handling precautions are required, except that large blocks of Ferrite
magnets are powerful, and care should be taken to ensure that they do
not snap towards each other.
Temperature Effects
Up to about 840°F, changes in magnetization are largely reversible,
while changes between 840°F and 1800°F are re-magnetizable. For all
Ferrite magnets, the degradation of magnetic properties is essentially
linear with temperature. At 350F, about 75% of room temperature
magnetization is retained, and at 550°F, about 50% is retained.
Magnetic Properties of Hard Ferrite:
Grade | Remanence Br | Normal Coercivity Hcb | Max. Energy Product (BH)max | |||||
MMPA | TDK | mT | Gs | KA/m | Oe | KJ/m3 | MGOe | |
Y15 | 280-360 | 2800-3600 | 128-192 | 1600-2400 | 14.3-17.5 | 1.8-2.2 | ||
Y20 | 320-360 | 3200-3600 | 128-192 | 1600-2400 | 18.3-21.5 | 2.3-2.7 | ||
Y25 | 350-390 | 3500-3900 | 152-208 | 1900-2600 | 22.3-25.5 | 2.8-3.2 | ||
Y30 | 385-400 | 3850-4000 | 176-192 | 2200-2400 | 27.5-30.0 | 3.45-3.8 | ||
Y32 | C-11 | FB4A | 400-410 | 4000-4100 | 192-220 | 2400-2750 | 30.0-32.0 | 3.8-4.0 |
Y35 | C-8B | FB4X | 410-420 | 4100-4200 | 220-264 | 2750-3300 | 31.5-33.0 | 4.0-4.2 |
Y30BH | 370-390 | 3700-3900 | 176-240 | 2800-3000 | 26.0-28.0 | 3.3-3.6 | ||
Y30HJ | C-9 | FB5A | 365-380 | 3650-3800 | 264-270 | 3300-3375 | 28.0-29.0 | 3.5-3.7 |
Y30H-1 | C-8A | FB4B | 380-390 | 3800-3900 | 230-250 | 2875-3125 | 27.0-29.0 | 3.4-3.7 |
Y33HJ | C-12 | FB5F | 395-400 | 3950-4000 | 275-285 | 3437-3562 | 28.5-30.0 | 3.58-3.8 |
Physical Properties of Hard Ferrite:
Parameters | Mark | Unit | Values | Remark |
Recoil Permeability | rec | Gs/Oe | 1.05-1.3 |
|
Curie Temperature | Tc | ℃ | ≥450 | |
Temp. Coefficient of Magnetic Induction | A(Br) | ℃-1 | -0.2% | 0-100℃ |
Temp. Coefficient of Inturensic Coerrice Induction | A(Hcj) | ℃-1 | -0.2-0.5% | 0-100℃ |
Density | d | G/cm3 | 4.6-5.0 | |
Specific Resistance |
| Ω.cm | ≥106 | |
Coefficient of Thermal Expansion | A | ℃-1 | 7-15X10-6 |
|
Hardness | HV | -- | 480-580 |
Block | TYPE | L | B | H | TYPE | L | B | H |
Block with a hole | F3.1521 | 152 | 102 | 25.4 | F3.4310 | 43.4 | 10.8 | 6~3 |
Disk | F3.1522 | 152.4 | 101.6 | 19.05 | F3.4225 | 42.5 | 25.6 | 6~3 |
Ring | F3.1523 | 152.4 | 101.6 | 12.7 | F3.4025 | 40 | 25 | 12~3 |
Segment | F3.1501 | 150 | 100 | 25.4 | F3.3624 | 36 | 24 | 10 |
F3.1153 | 115 | 32 | 15~4 | F3.3430 | 34 | 30 | 10 | |
F3.1015 | 101.6 | 50.4 | 20 | F3.3009 | 30 | 9 | 6 | |
F3.1021 | 102 | 102 | 25.4 | F3.3010 | 30 | 10 | 4 | |
F3.1025 | 102 | 51 | 25.4 | F3.3020 | 30 | 20 | 5 | |
F3.1001 | 100 | 100 | 25 | F3.3123 | 31.5 | 23 | 5~2 | |
F3.1007 | 100 | 75 | 25.4 | F3.3118 | 31 | 18.5 | 18 | |
F3.1005 | 100 | 50 | 19.05 | F3.2819 | 28 | 19 | 5 | |
F3.1002 | 100 | 50 | 25 | F3.2813 | 28 | 13 | 6 | |
F3.7520 | 75 | 50 | 25.4~3 | F3.2828 | 28.5 | 28.5 | 7 | |
F3.9034 | 90 | 34 | 20 | F3.2610 | 26 | 10 | 3.6~2 | |
F3.8565 | 85 | 65 | 20 | F3.2410 | 24 | 10 | 4 | |
F3.8025 | 80 | 25 | 10.4~3 | F3.2519 | 25 | 19 | 6~2 | |
F3.7830 | 78 | 30.43 | 9.3~3 | F3.2511 | 25 | 11 | 5~2 | |
F3.7651 | 76 | 51 | 20 | F3.2313 | 23.4 | 13.11 | 5~2 | |
F3.6734 | 67.8 | 34 | 20 | F3.2205 | 22 | 5.72 | 4.78~2 | |
F3.6520 | 65 | 20 | 5 | F3.2113 | 21.3 | 13 | 6 | |
F3.6030 | 60 | 30 | 10.4~3 | F3.2205 | 22 | 5.72 | 4.78 | |
F3.5431 | 54 | 31 | 15~3 | F3.2217 | 22 | 17 | 5 | |
F3.5019 | 50 | 19 | 6.1 | F3.2222 | 22 | 22 | 5 | |
F3.4820 | 48 | 20 | 10 | F3.2210 | 22 | 10 | 6 | |
F3.4722 | 47.6 | 22.2 | 10~3 | F3.2014 | 20 | 14 | 3.8 |
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