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Questions and answers about the grade of ferrite magnets

The specifications Y35, Y30BH, Y26H and HF 24/23 are a measure of the grade of the ferrite magnet used. From this designation, you can ascertain the following facts:
  1. Up to what maximum temperature you can use the magnet.
  2. How much "magnetic energy" per volume is stored in this magnetic material.

Table of Contents

Possible standards for physical properties

There are various standards for the physical features of ferrite magnets.
  • Chinese Standard SJ285-77
  • United States Industry Standard (US Ind. Standard)
  • International Electrotechnical Commission DIN IEC404-8-1
The standards differ mostly by the defined value spectrums.
Therefore, magnets of different standards can't be compared equally. Our magnets correspond to the Standard Y35 of the SJ-285-77. This standard is somewhat similar to C5 of the U.S. Industry Standard or HF26/18 of the DIN IEC 404-8-1.
The DIN IEC Standard is very common in Europe. The classification number is made up of the simplification of the minimum level of the energy product in kJ/m³ and the coercive field strength iHc in kA/m.
e.g. HF24/16: (BxH)max = 24.0 - 25.5 kJ/m³ / iHc = 160 - 180 kA/m
When we talk colloquially about the "power" of a magnet, we usually mean the strength of attraction on a ferromagnetic or magnetic surface. This surface typically consists of iron, industrial or structural steel or another magnet.
The strength is not only determined by the magnetic material used; equally important are the following factors:
  • Volume of the magnet
  • Shape of the magnet
  • Proportions of the magnet (e.g. the ratio of the diameter to the height of a disc magnet)
  • Combination with other materials; e.g. is the magnet mounted on a piece of metal, in a metal pot, or is it "free-standing".

What does the specification Y35 mean?

Y35 describes the grade of the magnet material used for ferrite magnets, according to the Chinese Standard SJ285-77. This is a common standard in China that we use as well. The exact physical values can be found in the table Physical magnet data.
The majority of ferrite magnets in our assortment are grade Y35:

How is the grade designation structured according to the Chinese standard SJ285-77?

The letter Y

In this standard, all grades of ferrite magnets begin with the letter Y. The Y stands for the material ferrite, derived from the first letter of the Chinese character for ferrite.

The number

The number (i.e. 35, 30, 26) represents the maximum energy product of the magnet in MGOe (mega-gauss-oersted). The MGOe is an indicator of the strength of the magnet. It shows how much energy the magnet can store. The following applies: the higher the number, the stronger the magnet. The highest possible maximum energy product for a ferrite magnet is 43, and the lowest energy product is 8. In our online shop, we carry ferrite magnets with a maximum energy product of 26, 30 and 35.
This number classification is based on the magnetic properties of the magnet and is not an indication of its quality. In the table with the physical magnet data, you can see the relationship between this classification and the physical values of a magnet.

The letters

The combination of letters at the end of the grade designation stands for a specific property of the ferrite magnet. The H, for example, signifies high coercivity aka coercive field strength (Hc). It indicates that the magnet loses its magnetic field at a slower rate. Compared to grades without the letter H, external effort is required to demagnetise it. The letter B, for example in grade Y35BH, stands for 'Br', denoting high remanence.