Understanding Radiation Magnetic Rings in One Text
Radiant magnetic rings are a type of circular permanent magnet with a special orientation, which are magnetized radially along the circumference of the ring. They can be widely used in fields such as servo motors, magnetic drives, magnetic bearings, and sensors, replacing spliced magnetic rings.
The main advantages of radiation magnetic rings include: 1. The radiation ring is an integral magnetic ring, with better dimensional accuracy control and simplified assembly process;
2. The surface field presents a sinusoidal waveform with uniform distribution and a small transition zone between magnetic poles, resulting in stable motor operation and low noise;
3. There are various magnetization methods and magnetic field distributions, including unipolar radiation, multipole direct charging, and multipole oblique charging magnetization, making the magnetic circuit design more flexible.
Radiant magnetic rings can be divided into magnetic field oriented and pressure oriented magnetic rings according to their orientation. Among them, sintered or bonded magnetic rings are mostly magnetic field oriented, while hot pressed/thermally deformed magnetic rings are mostly pressure oriented. According to the material, it can be divided into ferrite permanent magnet rings, rare earth permanent magnet rings, and other permanent magnet rings. Among them, rare earth permanent magnet rings mainly include samarium cobalt permanent magnet rings and neodymium iron boron permanent magnet rings. The highest magnetic performance is sintered or hot pressed/thermally deformed neodymium iron boron magnetic rings. According to shape, rings with an inner to outer diameter ratio less than 0.7 are considered thick walled rings, while rings with an inner to outer diameter ratio greater than 0.9 are considered thin-walled rings.
Due to the mature bonding process and low cost, the production of bonded neodymium iron boron radiation rings accounts for the largest proportion. However, the density and performance of adhesive magnetic rings are relatively low, and their high-end application scenarios are limited. However, high-performance sintered and hot pressed/thermally deformed neodymium iron boron radiation magnetic rings are prone to fragmentation during preparation, magnetization, and assembly due to significant differences in the shrinkage ratio and thermal expansion coefficient between the easy and difficult magnetization axes of neodymium iron boron grains, resulting in low yield and generally high prices. Japan was an early developer of radiation ring equipment and processes, with significant advantages in equipment accuracy, stability, and product grades. The research on radiation rings in China started relatively late, but currently many enterprises and research institutes can stably supply radiation ring products of various sizes and grades.
Regarding the size of the radiation ring, generally speaking: the adhesive radiation ring is less limited by size; Hot press radiation rings are mostly thin-walled magnetic rings, with a diameter of less than 30mm and a wall thickness of less than 3mm; The sintered radiation ring can produce products with an outer diameter greater than 200mm, a wall thickness exceeding 5mm, and a height less than 50mm. However, due to limitations in qualification rate and cost, the market mostly consists of small-diameter magnetic rings with an outer diameter of less than 100mm.
The following table is the product grade list for the "Sintered NdFeB Radiation Magnetic Ring" standard of Baotou Rare Earth Product Quality and Standardization Association. Purchasing personnel can make reasonable choices based on comprehensive factors such as product size, performance, and cost-effectiveness.