What is residual magnetic flux density?
What is residual magnetic flux density?
Residual magnetic flux density (Br) refers to the magnetic flux density that can be retained inside a magnetic material even if the external
magnetic field disappears after it reaches saturation magnetization under the action of an external magnetic field. Simply put, it measures the
ability of magnets to 'remember' magnetic fields.
v Physical meaning: Br is a key parameter in the hysteresis loop, representing the magnetization strength that a magnet can maintain even
after removing an external magnetic field.
v The relationship between Br and other magnetic performance parameters: Br, coercivity (Hc), and maximum magnetic energy product
(BHmax) jointly determine the comprehensive performance of the magnet. A high Br value usually means that the magnet has a stronger
magnetic field output capability. Measurement method for residual magnetic beam density
The common methods for measuring Br include:
v Hysteresis loop test: By drawing the hysteresis loop, the Br value can be directly read.
v Vibration Sample Magnetometer (VSM): Used to measure the magnetic properties of small-sized samples.
v Hall effect sensor: indirectly calculates the Br value by measuring the magnetic field strength.
Factors affecting residual magnetic beam density
v Material composition: The Br values of different magnetic materials (such as ferrite, AlNiCo, NdFeB) vary significantly. For example, the Br
value of NdFeB magnets is usually higher than that of ferrites.
v Manufacturing process: Sintering, casting and other processes can affect the microstructure of materials, thereby affecting the Br value.
v Temperature: High temperature may cause demagnetization of the magnet, and the Br value decreases with increasing temperature.
Practical Application of Residual Magnetic Beam Density
v Electric motors and generators: High Br magnets can improve the efficiency and output power of equipment.
v Sensor: The stable Br value ensures the accuracy and reliability of the sensor.
v Medical equipment, such as magnets in MRI, require high Br values to generate strong magnetic fields.
