WHAT ARE MAGNET GRADES?

Magnet grades are the Arabic numerals used to distinguish the different material properties. They are usually placed after the material name and a measure of magnets strength rating. For example: N42 of sintered ndfeb magnet, BNP10 of bonded neodymium magnet, 30H of smco 2:17, alnico5, ferrite Y30 or PA6 of injection molding ferrite.

For NdFeB materials, there are some suffix letters following the grade such as M, H or SH. These indicate maximum working temperatures (we use celsius temperature), which range from M (up to 100 °C) to AH (220 °C). The grade without suffix letter has maximum operating temperature 80°C, however N52 & N55 (the highest grade) only work at 60°C.

Other materials do not have as many different operating temperature ranges as sintered neodymium magnets, so there are no suffix letters to mark them, such as alnico magnets, which can all operate at 550°C.

HOW ARE MAGNETS RATED FOR STRENGTH?

If you look at these specification charts closely, you will find a rule. No matter for neodymium magnet or smco, their grade number are closely to their maximum energy product. That’s because magnet grades are based on maximum energy product, which relates to the magnetic flux output per unit volume.

Material
Grade
Br 
HcB 
HcJ
(BH)max.
Max Working Temp.
mT
 KA/m
 KA/m
KJ/m3
°C 
Neo
N35
1170-1200
860-900
≧955
263-279
≤80
Neo
N45SH
1330-1350
971-1003
≥1595
342-358
≤150
Neo
N35AH
1170-1190
876-915
≥2786
263-279
≤220
SmCo
YXG-28
1030-1080
756-812
≧1433
207-223
≤300
SmCo
YXG-35
1160-1200
868-908
≥1433
255-278
≤300
SmCo
YXG-30H
1080-1100
788-835
≥1990
220-240
≤350
Ferrite
Y35
430-450
215-239
217-241
33.0-38.2
≤180
Bonded Neo
BNP-10
670-720
424-480
640-800
76-84
≤160
AlNiCo
LNG60
900
110
112
60
≤550

ASK THE SUPPLIER DIRECTLY FOR MAGNETS STRENGTH RATING

In general, for magnets used in daily life, ferrite or low grade NdFeB is the most common choice.

For industrial use, N48H or samarium cobalt, which can withstand higher temperatures, is the most common choice.

For motor magnets, high temperature magnets N45SH, N40UH and SmCo32 are usually used.

And for precision instruments, Alnico and SmCo are more commonly used.

We can offer the complete range of permanent magnet materials, including neodymium, samarium cobalt, alnico or ferrite. In addition, injection molded and bonded magnets are available.

We also have rich experience to help you make a clear and simple choice. Please feel free to contact us if you have any question for choosing a material or grade.

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    WHAT IS THE RELATIONSHIP BETWEEN MAGNET GRADES AND STRENGTH?

    Generally, the higher grade number indicates the stronger magnetic force as well as more expensive. If you want to ask which magnet is stronger, N35 or N52? Given the same dimensions, of course the N52 magnets are more powerful and have a stronger magnetic field.

    While magnet grade is a good measure of the strength of a magnet, we cannot use it as a simple measure of the strength of the final magnet product. Because magnets are customised products, there is no fixed size and shape, and the performance of materials from different batches may vary a little.

    HOW CAN I MEASURE THE MAGNET STRENGTH?

    There are two common magnet strength measurements: one is for the pull force and the other is for the strength of the magnetic field.

    Pull strength is a very subjective measure. The professional tensioner is a necessary tool for measuring tension in the magnet industry. Other testing methods may lead to very different results. And the pull force is usually not very accurate as it depends on many external factors such as:

    • Test method
    • Operating temperature
    • The grade of magnet
    • The material of the object being attracted
    • The size of the object being attracted

    The magnetic field strength is a measurement of the magnetic field’s strength. You can test it by gauss meter on the surface of N and S poles and while testing, make sure there is no presence of any other magnets or ferromagnetic materials nearby.

    For magnet manufacturer, instead of magnetic field strength, testing magnetic flux is the most accurate measuring standard for judging whether the magnet qualified.

    CHOOSING THE RIGHT MAGNET MATERIAL

    Choosing the RIGHT magnet material is critical to the success of your project. It will be a challenge if you don’t know much about magnets.

    This is because not only do magnets contain a variety of materials, each material comes in many different grades. Each grade has different performance characteristics and has very different applications and operating conditions. There are cheap magnets and expensive magnets as well. We need to choose the most suitable one to save cost and achieve the best magnetic performace.

    When Choosing the right magnet grade, you need to consider the following as much as possible.

    the Comparison of different magnets strength rating

    KEY QUESTIONS TO NARROW DOWN THE OPTIONS

    • Magnetic strength: how much weight does the magnet need to hold, lift or attract?
    • Max. Working temp.: high temperatures will demagnetize the magnet, so it is important to know the maximum operating temperature of the magnet
    • Shape & size: the shape of the magnet is limited by materials and processing methods. The size and weight of the magnet also have an impact on the end application, so these aspects need to be considered when designing the magnet.
    • Magnet Cost – is there a budget price point to make the project viable?
    • Other environment:
      Is it likely to be exposed to corrosive environments or substances?
      Is it likely to be exposed to demagnetization or instability?
      What is the expected design life of the equipment?
      What type and volume of material is it attached to?
    magnet material comparison, magnets strength rating