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What do the different grades of sintered NdFeB mean?

by AOMag | post a comment

NdFeB magnetic grade is a friend of the magnetic industry-related industry who is in contact every day, then
- What exactly is behind these complicated brands?
- What are the differences between different grades of NdFeB magnetic materials?
- How to choose the right NdFeB magnetic material by grade?
Today, AOMAG will explain the system for everyone.
First, the common N-series NdFeB grades can be divided into seven categories: N, M, H, SH, UH, EH, and TH. In addition to the N category, each type will appear at the end of the product number. For example, N38M is the M series, N38TH is the TH series, and if there is no letter behind the "N38", then he will be the N series. (Of course, there are some uncommon and higher performance grades. Interested parties can understand for themselves. We only introduce more common ones today.)
Secondly, there are four main indicators for measuring the performance of sintered NdFeB products.
Br Remanence: Units are Tesla (T) and Gauss (Gs), 1Gs = 0.0001T. It refers to the magnetic induction intensity of a sintered NdFeB magnet when a magnet is magnetized by an external magnetic field to a technical saturation in a closed circuit environment. The popular term can be temporarily understood as the magnetic force of the magnet after magnetization.
Hcb Coercivity: The unit is Oersted or O/A (A/m), 1 A/m = 79.6 Oe. The value of the reverse magnetic field strength required to reduce the magnetic induction to zero when the magnet is magnetized in the reverse direction is called the magnetic induction coercive force. However, the magnetization of the magnet is not zero at this time, but the applied reverse magnetic field and the magnetization of the magnet cancel each other out. At this time, if the external magnetic field is removed, the magnet still has a certain magnetic property.
Hcj Intrinsic coercivity: The magnetization of the magnet is reduced to zero. The reverse magnetic field strength required to be applied is called intrinsic coercivity. His unit of measurement is the same as coercivity. The classification of magnetic material grades is divided according to the size of the internal coercivity. Low coercive force N, medium coercive force M, high coercive force H, extra high coercive force UH, extremely high coercive force EH, highest coercive force TH. The intrinsic coercivity of NdFeB magnets will decrease with increasing temperature. Therefore, when choosing NdFeB magnets, be sure to choose the brand that is suitable for us.
(BH)max Maximum energy product: represents the magnetic energy density established by the two magnetic pole spaces of the magnet, that is, the magnetostatic energy per unit volume of the air gap, which is the maximum value of the product of Br and Hcj. Its size directly indicates the performance of the magnet. . The number in the magnetic material grade represents the theoretical maximum magnetic energy product of the product.
Again, we can see that there are two units of measure for each performance indicator, because they use different unit systems—SI and CGS, ie, the International System of Units and the Gaussian unit system, which is like the length unit. The difference between "meter" and "li". There is a certain conversion relationship between the International System of Units and the Gaussian unit system, but it is more complicated, so we will not introduce it.
Finally, it is not difficult to find that the performance of sintered NdFeB products under each grade is not the only fixed value, but a numerical range. The performance range of different manufacturers is not exactly the same. Everyone needs to pay special attention to whether the performance of the supplier's products can meet your requirements. The latest national standard for sintered NdFeB (GB/T 13560-2017) promulgated by the General Administration of Quality Supervision, Inspection and Quarantine and the Standardization Committee was implemented in May 2018, which specifies the minimum or interval value of various performance indicators of different grades.





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