Friction Force Exerted on a Yarn in a Friction False Twisting Unit

The friction force acting on a yarn when twisted and for warded by the rotating disks of a false twisting unit is analyzed by the force balanced equations. The related mechanics is presented in basically the same formulation as reported earlier but the rotational motion of a yam around its axis is newly taken into account besides the traveling in the axial direction. The analysis can evaluate separately two components of the friction force;one twists the yarn and another pushes the yarn forward. Further the change in yam path on the disk surface as well as in yam tension is simulated by integrating a set of differential equations. Also is proposed the way to cast the equations into dimensionless ones by which numerical case studies can be appreciably reduced in the number of trials.