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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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