What is Magnet Grade?
Magnet grade is the Arabic numerals used to distinguish the different properties. It is usually placed after the material name.
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. It is a measure of magnets strength rating.
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.
Max Working Temp.
What is the Relationship Between Grade and Strength?
Generally, the higher grade number indicates the stronger magnetic force as well as more expensive. Although magnet grade is a good measure of the strength of a magnet, we can’t use it to measure the strength of a magnet in reality.
How Can I Measure the Magnet Strength?
There are two common measures of a magnet’s strength: one is the pull force and the other is 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
- Surface condition
- Operating temperature
- The shape of magnet
- The material of magnet
- 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, magnetic flow is the most accurate measuring standard for judging whether the magnet qualified.
Visual Guide: 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.
When Choosing the right magnets strength rating, you need to consider the following as much as possible.
Key Questions to Narrow Down the Options
- Magnetic strength: what does the magnet need to hold, lift or attract?
- Working temp.: what is the operating temperature range of the magnet?
- Shape & size: whether the shape is complex, the size is too large, and the weight is required?
- Magnet Cost – Is there a budgeted price point to make this project feasible?
- 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?
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 the unique 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.