Yarn twisting disc

An apparatus for friction false twisting an advancing yarn, comprising;

• a mounting bedplate,
• at least three spindles mounted to said bed-plate for rotation about fixed, parallel axes which are positioned at the corner points of an equilateral polygon having a number of sides corresponding to the number of spindles, with each spindle fixedly mounting a plurality of circular discs and with marginal portions of the discs of the spindles overlapping interdigitally at a point centrally between said spindles and so as to define an operative yarn path of travel extending axially therebetween,
• means for concurrently rotating each spindle in a common direction and such that twist is imparted to a yarn moving along said operative yarn path of travel by contact with the rotating discs,
• the improvement comprising:
• each of said discs comprises an annular flange mounted coaxially about the rotational axis of the associated spindle and having an annular yarn contacting peripheral surface over which the yarn is transversely advanced during its advance along said path of travel, said annular yarn contacting peripheral surface consisting of first and second annular segments which are axially adjacent each other, with one of said segments having a coefficient of friction and radius of curvature which are greater than the coefficient of friction and radius of curvature, respectively, of the other of said segments, said radius of curvature of said one segment being substantially uniform.