the weight w of the ring shaped rotator and the outside diameter d 1 and ring shaped top flange inside diameter d 2 and the relation between the width a along the radial direction and the height h along the axial directio between the sliding surfaces of the ring shaped rotator and the ring shaped supporter this rotary ring makes it possible to realize higher spindle speed and higher productivity of yarn application_number US 37602589 A description a rotary ring according to the present invention has a ring shaped rotator with a ring shaped top flange at a top part thereof supported slidably by a ring shaped supporter this ring shaped supporter is made of synthetic resin such as ethylene tetrafluoride polyethylene polystyrene nylon etc and the coefficient of friction u03bc between the ring shaped rotator and the ring shaped supporter is within the limits of 0 05 u2266 u03bc lt 0 3 in the case where the weight of a ring shaped rotator is made constant if the coefficient of friction u03bc is less than 0 05 frictional force becomes small and rotation of the ring shaped rotator increases nearly up to the spindle speed as a result wear of the ring shaped supporter increases abruptly on the other hand if the coefficient of friction exceeds 0 3 frictional force becomes large and rotation of the ring shaped rotator becomes too slow as a result fluffing occurs frequently and quality of yarn is lowered fig4 shows the relation between the ratio of rotation between r p m of the ring shaped rotator and r p m of spindle and the fluffing of 3 mm in length amount of wear of the ring shaped.