What are the specific requirements for the performance of motor magnets?
Publish Time: 2024-08-22
The performance requirements of motor magnets usually include the following aspects:
Magnetic properties:
High remanence: The higher the remanence, the stronger the magnetic field can be generated by the motor under the same volume and current, and the greater the torque and power output. For example, the high remanence of NdFeB magnets makes it widely used in miniaturized and high-efficiency motors.
High coercivity: The high coercivity makes the magnets resistant to demagnetization. During the operation of the motor, they can withstand large reverse magnetic fields and temperature changes without demagnetization, ensuring stable motor performance. For example, in some motors with complex working environments, high coercivity magnets are required to ensure long-term stable operation.
High magnetic energy product: The magnetic energy product is an indicator of the ability of magnets to store magnetic energy. A high magnetic energy product can store more magnetic energy in a smaller volume, provide a strong magnetic field for the motor, and help to achieve miniaturization and high-efficiency design of the motor.
Temperature characteristics:
High temperature resistance: The motor will heat up during operation, especially in some high-temperature environments or long-term high-load working conditions. The magnets need to have good high-temperature resistance to ensure that the magnetic properties are stable at high temperatures and no significant demagnetization occurs. Different types of motor magnets have different high temperature resistance capabilities. For example, some NdFeB magnets can maintain stable performance at around 200℃, while SmCo magnets can work at higher temperatures (250℃ - 350℃ or even higher), which are suitable for high-temperature motors or occasions with strict temperature requirements.
Low temperature resistance: In some motors used in low temperature environments, such as equipment used in the aerospace field or cold areas, the magnets need to maintain stable magnetic properties at low temperatures, without embrittlement, cracking and other problems, to ensure the normal operation of the motor under low temperature conditions.
Mechanical properties:
Sufficient strength and hardness: The motor will be subjected to various mechanical stresses during operation, such as vibration, impact, centrifugal force, etc. The magnets must have sufficient strength and hardness to withstand these stresses to prevent cracking, damage or deformation. For example, in a high-speed rotating motor, insufficient strength and hardness of the magnets may cause fragmentation and damage to the motor.
Good toughness: With a certain toughness, the magnets can absorb energy and are not easy to break when they are impacted or vibrated, thereby improving the reliability and service life of the motor.
Machinability: It is easy to process into various shapes and sizes to meet the needs of different motor design and manufacturing. For example, common motor magnets have tile-shaped, square, ring-shaped and other shapes.
Corrosion resistance: For motors working in some humid, chemical or harsh environments, magnets should have good corrosion resistance to prevent corrosion from affecting magnetic properties and service life. For example, motors used in the chemical industry, marine environment, etc. have high corrosion resistance requirements for magnets, and usually use special surface treatment or select corrosion-resistant materials to improve the corrosion resistance of magnets.
Dimensional accuracy: The dimensional accuracy of magnets directly affects the assembly and performance of motors. Excessive dimensional deviation may cause difficulty in installing magnets in motors, uneven gaps, affect the magnetic field distribution and operating efficiency of motors, and may even cause motor failure. Therefore, motor magnets usually need to strictly control dimensional accuracy to ensure that they are within the specified tolerance range.
Stability: The performance of motor magnets should remain stable during long-term use, including magnetic properties, mechanical properties and other related properties. This requires that the material and manufacturing process of the magnets have good stability and are not significantly changed by factors such as time and environment. For example, after a long period of storage or use, the magnetic properties of the magnet should not be significantly attenuated to ensure the long-term stable operation of the motor.
Low magnetic loss: Magnetic loss will lead to energy waste and reduced motor efficiency, so the motor magnet should have low magnetic loss characteristics. This includes hysteresis loss, eddy current loss, etc. By optimizing the material, structure and manufacturing process of the magnet, the magnetic loss can be reduced and the energy efficiency of the motor can be improved.
Magnetization performance: For motor magnets that need to be magnetized, magnetization performance is crucial. Magnetization should be uniform and sufficient so that the magnet obtains the required pole distribution and magnetic field strength to ensure the performance of the motor. Magnetization parameters (such as magnetization current, magnetic field strength, magnetization time, etc.) need to be precisely controlled according to the material of the magnet and the requirements of the motor to ensure that the magnetization effect meets the design standards.
