all kinds of magnetic components in motor rotors according to the requirement of customer in motor industry, such as DC Motors, PM Motors, Servo Motors and Linear Motors etc and this kind of magnetic components are usually made of permanent magnets and machined parts and are assemblied by very strong glue. The permanent magnets used in rotors include NdFeB magnets, Ferrite magnets, SmCo magnets and Alnico magnets etc and the housing materials include stainless steel, Aluminum and brass etc and they are assemblied outside or inside the body of metal housing with multi-poles by arc shaped magnets