False Twist in Core Yarn Friction Spinning

Abstract

We have analyzed false-twist distribution in filaments along core yams produced on a friction spinning machine, considering the effective parameters for imparting twist to the filaments and yarns. The theoretical analysis is based on twist distribution along the conical yarn tail. Twist is applied to the yam tail by suction air pressure and rotation of the friction rollers. The theoretical results are compared with the experimental data. The results show that although, theoretically, the twist imparted to a filament is zero, there is still some twist in the filament in both directions (S and Z) in a short yarn length. As the sample length increases, these twists combine and cancel each other. The resulting twists tend toward zero in longer yam samples. Filament pre-tension also affects the false twist of the filament. The results show that the remaining twist in filaments in non-pre-tensioned yams is greater than that in pre-tensioned yams.