Abstract
An investigation is reported in which factorial experiments were conducted to study the influence of the design of the yarn-withdrawal tube (or nozzle) on the diameter and hairiness of open-end-spun acrylic-fibre yarns. Three nozzle types, combined with three values of yarn linear density and five values of twist multiplier, were studied for four different (but equal-diameter) rotor types. lt is shown that the nozzle type has very little influence on yarn diameter but has a more significant effect on yarn-hairiness parameters. As the nozzle diameter increases, yarn hairiness also tends to increase, but, when the nozzle is grooved, an interaction is produced between yarn friction and the false twist generated that leads to a yarn that is less hairy when tested on the Digital ITQT Hairiness Meter. The principle of measurement of the apparatus used can lead to different results and trends when applied to this problem.