What kind of magnet is most used in motor?
The following figure shows NdFeB strong magnetic tile, one of the common DC motors.
At present, motor mainly uses NdFeB strong magnetic material, including sintered magnet and bonded magnet. Why? Because of the small size, light weight, high torque inertia ratio, high response of servo system, high power and speed / weight ratio, high starting torque and power saving.
Introduction to the shape of magnet for motor:
The shape of the magnet used in motor is mostly of tile type, ring, bread type or trapezoid type, which can be used in different motor motors, such as permanent magnet motor, AC motor, DC motor, linear motor, brush less motor, etc. People usually use the attraction and repulsion of motor magnet and motor magnet to drive. Generally, we choose the radial symmetrical magnetizing type motor magnet to form a ring, because sintered NdFeB is an anisotropic material, so it is difficult to make complex magnetization direction. At present, there are also radial magnetization products of sintered Nd-Fe-B motor magnets, but there are many restrictions on size and brand, and the magnetic properties are extremely unstable, and the consistency is very poor. At the same time, the mold coil and magnetizing fixture are very expensive.
At present, the demand of motor magnet is very large. Magnet is its core component. Neodymium iron boron permanent magnet can be used in micro special motor, medium and small motor and large generator. Samarium cobalt motor magnet is also used for special purposes. Ferrite magnet (tile shape) is used for low-end products.
Electric vehicle motor is generally made of Ni or epoxy coated NdFeB magnetic tile, which can withstand high temperature of more than 120 degrees, so it is made of materials above sh. in addition to rare earth neodymium, iron, boron, dysprosium, praseodymium, terbium, cobalt and other additives, some people are specialized in recycling magnets on the motor to recover these metals.