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.

Effect of spandex filament draw ratio on elastic core spun yarn properties in friction spinning

“…Therefore, the tip of the yarn tail in this region of the yarn forming zone is more stable for core yarns which may cause better yarn formation in comparison with conventional yarns. 7,8,29 As Figure 4 shows, the S3 values decrease as the spandex draw ratio increases over the range 2 to 3.5, with no further change from 3.5 to 4.2. The results of statistical analyses show that the mean S3 values of elastic core spun yarns are significantly different over the range 2 to 3.5 and not significantly different from 3.5 to 4.2 at the 5% level of significance.…”

“…In conventional core yarn spinning, the core filament such as polyester, nylon, polyurethane, carbon, etc., provides high strength and other functional characteristics, while the staple fibers such as cotton, wool, staple synthetic fibers, etc., in the sheath provides the traditional look, feel, and comfort. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] In elastic core spun yarn, whereas the purpose of using the spandex in the core is to increase the elasticity of the yarn, the strength of yarn depends on the properties of core and sheath and their ratio in the yarn and method of spinning. The manufacturing process of elastic core spun yarns mainly consists of feeding a stretched spandex filament to the spinning unit, where it is covered by staple fibers.…”

Limits of Hollow Yarn in Friction Spinning

“…However, there is no doubt that pvA filament irregularity is affected by spinning because of the mechanism of core yam formation and false twist of the filament in friction spinning. [5,6]. Consequently, we may conclude that both the methods of combination or spinning and PvA extraction increase holliow yarn irregularity.…”

Fiber Feeding onto the Yarn Tail in Friction Spinning

“…In friction spinning, the fibers are transferred from the supply to the yarn tail by the transport channel (Figure 1 ) [11][12][13]. The position of fibers in the yam depends on the landing point of fibers on the yarn tail and their shape inside the transport channel.…”