Demagnetization Curve or BH Curve
In practical applications, a magnet must generate a magnetic field and is therefore subject to the very magnetic force it creates.
The part of the hysteresis curve that indicates how the magnet behaves in the presence of demagnetizing fields is located in the second quadrant, and is known as the demagnetization curve. This curve is fundamentally important because it shows the key values used to classify a permanent magnet.
The values of interest are:
- Residual magnetization (Br)
- Coercivity (Hc)
- Maximum energy product (Bhmax),
which represents the maximum possible value of the product of B and H. Graphically, this corresponds to the area under the curve between these values and indicates the maximum energy output of the magnet.
We generally recommend using permanent magnets under working conditions slightly below their Bhmax value.
To achieve these specific working levels, the magnet must first be magnetized to saturation. Then, by applying opposing magnetic field cycles of appropriate intensity, the desired Bhmax operating point can be reached..
