Samarium - cobalt magnets have the characteristics of high - temperature resistance (up to 400℃), shiny metallic color, and relatively high cost. Through comprehensive research, it is found that samarium - cobalt magnets are rarely used in micro - electromechanical systems.
For permanent ferrite magnets, it is undoubtedly better than neodymium - iron - boron magnets in terms of high - temperature resistance (controlled below 400℃). However, to make ferrite magnets match micro - motors and have unique characteristics, the process cost is very high, and at the same time, the rejection rate is also very high because they are prone to breakage or wear and corner chipping.
Permanent - magnet motors using neodymium - iron - boron magnets as motor magnets have small sizes, light weights, high torque - inertia ratios, high - response servo systems, high power and speed/weight ratios, high starting torques, and energy - saving. The forms of motor magnets are mostly tile - shaped, ring - shaped, or trapezoidal, which can be used in different motors, such as permanent - magnet motors, AC motors, DC motors, linear motors, and brushless motors.
The following is an introduction to neodymium - iron - boron magnets.
(1) People usually use the attraction and repulsion of magnets to drive. Generally, radially symmetrically magnetized tile - shaped magnets are usually selected to form a ring. Sintered neodymium - iron - boron is an anisotropic material and cannot be formed into a slightly more complex magnetization target desired by customers at one time.
(2) Neodymium - iron - boron magnets are also divided into sintered neodymium - iron - boron and bonded neodymium - iron - boron, and bonded neodymium - iron - boron is more recognized by the industry. At present, some manufacturers can also carry out radial magnetization of bonded neodymium - iron - boron magnets, but there are many requirements for size and grade (surface magnetic strength), and the magnetic performance also has process requirements for stability and consistency. At the same time, the mold coils and magnetization fixtures are very expensive. If it is not a supplier with stable quality, few manufacturers will choose bonded neodymium - iron - boron.
