Magnet is an object that can generate magnetic field and is a magnetic dipole that can attract ferromagnetic substances such as iron, nickel, cobalt and other metals. It can be widely used in electric motors, engines, voice coil motors, magnetic resonance imagers, communications, control instruments, audio equipment, etc. In the field of motors, permanent magnet motors using NdFeB magnets as motor magnets are small in size, light in weight, high in torque-to-inertia ratio, and high in servo system response. Magnets play an important role in the development of modern industry and electronic technology, and are more and more widely used nowadays.