The ring SmCo magnet is mainly magnetized through the length or diameter. At this moment, no radial sintered SmCo ring magnet is produced in China yet. If customers prefer radial SmCo rings, we suggest they use radial bonded SmCo rings or diametrical sintered segments to form a ring magnet instead.
The axially magnetized SmCo ring magnet is easy to produce and machine from a cylinder magnet block or a ring magnet block directly. And then the inspection items for the axially magnetized ring is almost same as other shaped magnets, including magnetic properties, size, appearance, flux or flux density, appearance, magnetic loss, coating thickness, etc.
The diametrically orientated ring SmCo magnet needs producing from a block shaped magnet block mainly, because the directly pressed diametrical ring is easy to crack in pressing, sintering and following machining processes and the crack is difficult to be detected especially for the ring SmCo magnets supplied unmagnetized. If the crack is only found after ring magnets are delivered, assembled and magnetized by customers, it will generate too much cost and then problem. Sometimes, a notch or slot is produced on the unmagnetised ring magnet so as to make it easy for customers to identify the magnetization direction during their assembly process.
For the diametrically magnetized SmCo ring magnets, the requirement for the angle deviation of the magnetization direction is strict so as to ensure its better working result. Normally the angle deviation is controlled within 5 degrees and sometimes strictly to 3 degrees. Therefore the tolerance of the orientation direction should be controlled well during pressing and machining process. In the final inspection process, there should be inspection method to detect the angle deviation result. We usually inspect the magnetic field surrounding the outer ring to form a sinusoidal waveform to evaluate the angle deviation.
