Cotton Ply Yarn Twist and Filling Stop in Air-Jet Woven Mori Fabric

Abstract

The aerodynamic interaction between weft yarn and compressed air plays a critical role in determining weaving performance in air-jet looms. Although increasing ply twist is known to reduce yarn hairiness by improving yarn compactness, its influence on actual filling stop behavior under industrial weaving conditions has not been comprehensively investigated. This study investigated how cotton ply yarn twist affects yarn hairiness and filling stop rate during the production of 100% cotton greige (mori) fabric on a Toyoda air-jet loom under commercial manufacturing conditions. Cotton Ne 20 ply yarns were prepared from two Ne 40 single yarns using a two-for-one twisting process with ply twist levels of 400, 600, and 800 TPM while maintaining identical yarn count, fiber composition, and weaving parameters. Yarn hairiness was measured using a COVATEST hairiness tester, whereas weaving performance was evaluated based on the filling stop rate recorded over five weaving repetitions of 100,000 picks for each twist level. One-way ANOVA was performed to assess the effect of ply twist on filling stop rate, followed by Tukey’s HSD test for post-hoc comparisons. In addition, linear regression analysis was performed to quantify the observed association between yarn hairiness and filling stop rate. Yarn hairiness decreased progressively from 5.63 ± 0.06 at 400 TPM to 4.54 ± 0.05 at 800 TPM, corresponding to an overall reduction of 19.36%. Conversely, the filling stop rate increased from 0.80 ± 0.84 to 6.20 ± 1.48 stops per 100,000 picks as the ply twist increased. Statistical analysis confirmed that ply twist significantly affected the filling stop rate (F = 19.895, p < 0.001). Linear regression showed a strong negative association between yarn hairiness and filling stop rate (r = ?0.855, R² = 0.731, p < 0.001). However, because both variables varied systematically with ply twist, this association does not establish an independent causal effect of hairiness on filling stop occurrence. The observed increase in filling stop rate with higher ply twist, together with the reduction in yarn hairiness, suggests that changes in yarn surface characteristics may influence weft insertion under compressed airflow. A possible explanation, consistent with previous studies, is that the smoother and more compact yarn surface associated with higher ply twist may reduce aerodynamic interaction during weft insertion. However, this aerodynamic mechanism was not directly measured in the present study. These findings demonstrate an association between ply twist, yarn hairiness, and filling stop behavior under commercial air-jet weaving conditions, providing practical insight into ply yarn design for weaving performance.