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NdFeB Magnet Knowledge
Oct 22, 2018

NdFeB magnet knowledge


Permanent magnet material: The permanent magnet material is magnetized by an external magnetic field and does not disappear. It can provide a stable magnetic field to the external space. There are four commonly used metrics for NdFeB permanent magnets: Remanence (Br) units are Tesla (T) and Gauss (Gs) 1Gs = 0.0001T.


A magnet is magnetized by an external magnetic field in a closed circuit environment to cancel the external magnetic field after the technology is saturated. At this time, the magnetic induction intensity exhibited by the magnet is called remanence. It represents the maximum flux value that the magnet can provide. It can be seen from the demagnetization curve that it corresponds to the case where the air gap is zero, so the magnetic induction strength of the magnet in the actual magnetic circuit is smaller than the remanence. NdFeB is the highest practical permanent magnet material found in Br today. The magnetic coercivity (Hcb) unit is A/m (A/m) and Oe (Oe) or 1 Oe≈ 79.6A/m.


The value of the reverse magnetic field strength required to reduce the magnet's inductive strength to zero when the magnet after the technical saturation magnetization is reversed is called the magnetic coercive force (Hcb). 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. (The external magnetic induction performance is zero.) At this time, if the external magnetic field is removed, the magnet still has a certain magnetic property. The coercive force of NdFeB is generally above 11000 Oe.The intrinsic coercive force (Hcj) unit is A/m (A/m) and Oe (Oe)1 Oe≈79.6A/m


The magnetization of the magnet body is reduced to zero. The reverse magnetic field strength to be applied is called the intrinsic coercive force. The intrinsic coercivity is a physical quantity that measures the anti-demagnetization ability of a magnet. If the applied magnetic field is equal to the intrinsic coercivity of the magnet, the magnetism of the magnet will be substantially eliminated. The Hcj of NdFeB will decrease with increasing temperature, so you should choose a high Hcj grade when you need to work in a high temperature environment.


The unit of magnetic energy product (BH) is Coke/m3 (J/m3) or high (GOe) 1 MGOe≈7. 96k J/m3 The product of B and H at any point on the demagnetization curve is both BH we call the magnetic energy product, and the maximum value of B x H is called the maximum energy product (BH)max. The magnetic energy product is one of the important parameters of the energy stored by the constant magnet. The larger the (BH)max, the larger the magnetic energy contained in the magnet. When designing the magnetic circuit, the working point of the magnet should be as close as possible to the B and H corresponding to the maximum magnetic energy product.