Powerful magnets: Powerful magnets do not disappear after being magnetized by an external magnetic field, and can provide a stable magnetic field to the external space. There are four commonly used measurement indicators 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 After the technology is saturated, the external magnetic field is cancelled, and the magnetic induction intensity of the magnet at this time is called remanence. It represents the maximum magnetic flux value that the magnet can provide. It can be seen from the demagnetization curve that it corresponds to the situation when the air gap is zero, so the magnetic induction intensity of the magnet in the actual magnetic circuit is smaller than the remanence. NdFeB is the practical powerful magnet with the highest Br found today.

The unit of magnetic coercivity (Hcb) is Ampere/meter (A/m) and Oersted (Oe) or 1 Oe≈79.6A/m. When the magnet after technical saturation magnetization is reversely magnetized, the The value of the reverse magnetic field strength required for the magnet induction to drop to zero is called the magnetic induction coercivity (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 intensity is zero) If the external magnetic field is canceled at this time, the magnet still has certain magnetic properties. The coercivity of NdFeB is generally above 11000Oe.

Intrinsic coercivity (Hcj) units are Ampere/meter (A/m) and Oersted (Oe) 1 Oe ≈ 79.6A/m. The strength of the reverse magnetic field required to reduce the magnetization of the magnet to zero , which we call the intrinsic coercivity. Intrinsic coercivity is a physical quantity that measures the magnet's ability to resist demagnetization. If the applied magnetic field is equal to the intrinsic coercive force of the magnet, the magnetism of the magnet will be basically eliminated. The Hcj of NdFeB will decrease with the increase of temperature, so the grade with high Hcj should be selected when it needs to work in a high temperature environment.

The unit of magnetic energy product (BH) is joule/meter3 (J/m3) or Gao·Ao (GOe) 1 MGOe≈7.96k J/m3. The product of B and H at any point on the demagnetization curve is BH and we call it magnetic energy product, and the maximum value of B×H is called the maximum magnetic 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 greater 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 B and H corresponding to the maximum magnetic energy product.