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MAGNETIC PROPERTIES OF FERRITE MAGNETS

Ferrite magnets, also known as ceramic magnets, provide the lowest magnetic field strength of all permanent magnetic materials with a maximum energy product range of 0.8-5.3 MGOe. However, they are by far the most cost effective to manufacture in large volumes, which is a reason why they are commonly used for commercial, high volume production runs where space, and therefore size of the magnet is not a limiting factor. Ferrite magnets can generally be manufactured in individual blocks as large as 152mm x 101mm x 25mm (6in x 4in x 1in).

There are two types of ferrite magnets manufactured today, strontium ferrite (SrO.6Fe203) and barium ferrite (BaO.6Fe203). Strontium ferrite are the most popular as they provide the best magnetic properties. Below, you can see a list of all the commercial available strontium ferrite magnet grades and their magnetic properties.

GradeRemanence (BR)
mT
(KGS)
Coercive Force (Hcb)
kA/m
(kOe)
Intrinisc Coercive Force (Hcj)
kA/m
(kOe)
Max. Energy Product (BH) max
kJ/m3
(MGOe)
Max. Operating Temp
TW
Y8T 200-235
(2.0-2.3)
160
(2.0)
280
(3.5)
6.5-9.5
(0.8-1.2)
180°C
Y10T 200-235
(2.0-2.3)
160
(2.0)
280
(3.5)
6.4-9.6
(0.8-1.2)
180°C
Y20 320-380
(3.2-3.8)
190
(2.4)
195
(2.4)
18-22
(2.3-2.8)
180°C
Y22H 310-360
(3.1-3.6)
250
(3.1)
320
(4.0)
20-24
(2.5-3.0)
180°C
Y23 320-370
(3.2-3.7)
190
(2.4)
230
(2.9)
20-25
(2.5-3.2)
180°C
Y25 360-400
(3.6-4.0)
170
(2.1)
200
(2.5)
22.5-28.0
(2.8-3.5)
180°C
Y26H 360-390
(3.6-3.9)
250
(3.1)
255
(3.2)
23-28
(2.9-3.5)
180°C
Y27H 370-400
(3.7-4.0)
250
(3.1)
255
(3.2)
25-29
(3.1-3.6)
180°C
Y28 370-400
(3.7-4.0)
210
(2.6)
220
(2.7)
26-30
(3.3-3.8)
180°C
Y30 370-400
(3.7-4.0)
210
(2.6)
220
(2.7)
26-30
(3.3-3.8)
180°C
Y30BH 380-390
(3.8-3.9)
235
(2.9)
245
(3.0)
27-30
(3.4-3.8)
180°C
Y30H 380-415
(3.8-4.1)
300
(3.7)
335
(4.2)
27-32
(3.4-3.1)
180°C
Y32 400-420
(4.0-4.2)
190
(2.4)
195
(2.4)
30.0-33.5
(3.8-4.2)
180°C
Y32H 400-440
(4.0-4.4)
240
(3.0)
250
(3.1)
31-35
(3.9-4.4)
180°C
Y33 410-430
(4.1-4.3)
250
(3.1)
255
(3.2)
31.5-35.0
(4.0-4.4)
180°C
Y33H 410-430
(4.1-4.3)
270
(3.4)
275
(3.4)
31.5-35.0
(4.0-4.4)
180°C
Y34 420-440
(4.2-4.4)
230
(2.9)
235
(2.9)
32.5-36.0
(4.1-4.5)
180°C
Y35 430-450
(4.3-4.5)
240
(3.0)
240
(3.0)
33.1-38.2
(4.2-4.8)
180°C
Y36 430-450
(4.3-4.5)
239
(3.0)
241
(3.0)
33.1-38.2
(4.2-4.8)
180°C
Y38 440-460
(4.4-4.6)
305
(3.8)
310
(3.9)
36.6-40.6
(4.6-5.1)
180°C
Y40 440-460
(4.4-4.6)
354
(4.4)
360
(4.5)
37.5-41.8
(4.7-5.3)
180°C

Unfortunately, there are different naming standards used in different markets. The above ‘Y’ nomenclature is a Chinese standard, and the most widely used. Less regularly used is the ‘C’ American nomenclature and the ‘HF’ European standard. The magnetic properties of each of the standards are comparable. If you are more familiar with the American or European standard, you may find the following quick reference guide useful.

Quick cross reference:-

C5 = Feroba 2 = Fer 2 = HF26/18 = Y30

C8/C8A = Feroba 3 = Fer 3 = Y30H-1

C1 = Y8T / Y10T

C7 = Y26H-2 C8B = Y33

C9 = Y30H-2

C10 = Y33H

C11 = Y34

C12 = Y30H-2

 

Ferrite magnets are non-conductive and will not corrode as they are essentially already made from rust (iron oxide) and therefore cannot corrode further. They also maintain their performance in high temperatures and can be used in temperatures up to 250 degrees Celsius before any loss in performance occurs. However, ferrite magnets are susceptible to demagnetisation by stronger magnetic fields, which is why you will not find rare earth and ferrite magnets working together in the same application. Uniquely, their resistance to demagnetisation actually improves as the working temperature rises making them particularly useful for electric motors.

 

Ferrite magnets are typically produced in standard shapes such as discs, arcs, blocks and rings rather some of the more intricate shapes that you will find rare earth magnets produced in. At Magnet Expert Ltd we have the capability to produce bespoke ferrite magnets; however tooling charges for bespoke ferrite magnets are often high due to the nature of the material and the manufacturing process. If you have an enquiry about ferrite magnets please give our experts a call today on 0845 5194701.