Yarn Property Control on a Twist Drafting Frame1

Abstract

Twist drafting has desirable properties for small-scale production of functional yams. In twist drafting, a yarn is directly spun out from a large mass of fibers, and the withdrawal tension in the yarn is used to maintain steady-state conditions of yam forming and yarn evenness. This work presents a mechanical analysis of twist drafting and a related experiment. The analytical results reveal the relation between the yarn properties of linear density and twist rate and the operational parameters for spinning of withdrawal tension in the yarn being spun out and the porosity ratio in the mass. The relation permits control of the linear density and twist rate of the yarn independently to a certain extent and systematically, which is impossible with conventional twist drafting.I