What do the different grades of sintered NdFeB mean?
The grades of NdFeB strong magnet are people who are in magnetic material related industries will contact every day. So what do they exactly mean behind these complicated grades? What are the differences between different grades of NdFeB magnetic materials? How to choose the right NdFeB magnetic material by grades? Today, the Courage magnet supplier will explains it systematically for everyone.
Those who don’t understand the performance parameters of sintered NdFeB magnets may be directly confused. Let’s first talk about the connotation of this.
First, the common sintered NdFeB grades can be divided into seven categories: N, M, H, SH, UH, EH, and TH. In addition to the N category, other types will appear at the end of the product number. For example, the N38M is the M series, the N38TH is the TH series, and if there is no letter after the "N38", then it is the N series. (Of course, there are some uncommon and higher performance grades, if your are interested, you can learn it by yourself. 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 in a closed circuit environment to remove the external field after to a technical saturation. Generally speaking, it 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 strength of a reverse magnetic field applied to reduce the magnetization of a magnet to zero is called intrinsic coercivity. His unit is the same as coercivity. The classification of magnetic material grades is divided according to the value of the Intrinsic 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 value directly indicates the performance of the magnet. The number in the magnetic material grade represents the theoretical maximum energy product of the product.
In addition, we can see that there are two units of measure for each performance indicator, because they use different unit systems—SI and CGS, that is, the international units system and the gaussian units system, which is like the difference between "meter" and "li" of the length unit. There is a certain conversion relationship between the international units system and the gaussian unit system, but it is 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 magnet supplier's products can meet your requirements.