Hysteresis in an axial rotating SMB used in the ring spinning process

Superconducting magnetic bearings are passive stable magnetic levitating bearings which only need a material depending cryogenic temperature for their operation. The application of a rotating superconducting magnetic bearing (SMB) with high rotational speed in a ring spinning machine replaces the traditional, friction afflicted ring-traveler twist element. Ring spinning is the most common process to produce short stable yarn in textile industry. The SMB twist element significantly reduces the productivity limiting friction heat in the spinning process and thus the process speed will be increased from commonly 25000 rpm up to 50000 rpm. In this application melt textured YBa 2 Cu 3 O 7-x (YBCO) is used as superconductor and NdFeB as permanent magnet (PM). The PM ring rotates driven by the yarn and thereby imparts twist in it. The yarn force on the PM is an eccentric acting point force which leads to a tilt of the PM ring in the position to the superconductor ring. In combination with high rotational speed this tilt leads to a significant heat input in the superconductor due to hysteresis.