Systematic investigation of twist generation and propagation in a modified ring spinning system

Twisting is an important process used to form a continuous yarn from short staple fibers and to determine the structure and properties of the resultant yarn. This paper systematically examines the yarn twisting process in a modified ring spinning process based on a theoretical model proposed recently. To reduce the number of experiments, response surface methodology (RSM) involving a central composite design (CCD) in three factors—twist multiplier, speed ratio and wrap angle—was successfully employed for the study and analysis. The significant terms of the models were studied, and it was discovered that the speed ratio and wrap angle are statistically significant for the responses of twist efficiency, propagation coefficients of twist trapping, and congestion. More importantly, linear relationships were found among the three responses.

Theoretical study of the effects on yarn strength in a modified ring spinning system

A modified ring spinning system using a dynamic twist-resistant device has been employed to produce yarn. The modified device blocks twist to propagate to the spinning triangle, which changes the distribution of twist in the spinning area and increases the height of the spinning triangle. In this paper, two kinds of yarn counts (30 and 40 Ne) are spun in the conventional and modified ring spinning with twist multipliers of 3.2, 3.6, and 4.0. The results show that the yarn spun by the modified ring spinning system possesses a higher strength compared with the conventional yarn except in the higher twist multiplier. The increase in yarn strength was theoretically analyzed according to the model of yarn strength. The yarn strength was calculated by considering the original fiber strain in the yarn and the fiber strain due to yarn strain. In the model, the fiber migration was considered and the fiber entanglement caused by fiber migration was ignored to simplify the calculation. Four potentially important parameters of the spinning triangle, the height of the spinning triangle, the migration coefficient, the inclination angle, and the spinning tension, were proposed and their individual and interaction effects on yarn strength were analyzed. The results demonstrate that yarn strength increased with the increase of height of the spinning triangle and the migration coefficient. The inclination angle and the spinning tension have a relatively small influence on yarn strength when the height of the spinning triangle is higher.

Analyzing the effect of spinning process variables on blow room blended cotton melange yarn quality

Purpose The use and importance of mélange yarn in apparel sector is increasing day by day. With the gradual increase in market share, achieving the desired quality level of mélange yarn remains a challenge for yarn manufacturing industry. The purpose of this paper is to investigate the effect of raw material (dyed fiber percentage in the mixing), important spinning process variable (yarn twist multiplier) and productivity (spindle rpm of ring frame) on properties of cotton mélange spun yarn. Design/methodology/approach Box and Behnken Design of experiment has been used to investigate the important yarn quality parameters like evenness, imperfection, hairiness, breaking strength and breaking elongation of blow room blended cotton mélange yarn. The quadratic regression model is used to derive the statistical inferences about sensitivity of the yarn quality parameters to the different process variables. The response surfaces are constructed for depicting the geometric representation of yarn quality parameters plotted as a function of process variables. Findings The study shows that shade depth and spindle speed have significant effects on the mélange yarn unevenness and imperfections. Mélange yarn strength and hairiness are significantly affected by shade depth and yarn twist multiplier (TM). Yarn elongation at break is only influenced by the spindle speed. A darker shade is responsible for higher yarn unevenness, imperfection, hairiness and lower yarn strength. A higher spindle speed is also liable for deterioration of yarn quality. Practical implications Many spinning industries are planning to convert their existing spindles from normal gray yarn production to mélange yarn manufacturing. The outcome of this study will lead to achieve better mélange yarn quality and productivity by the industry. Originality/value Research on mélange yarn is itself scant. This study is exclusively conducted to analyze the individual and interactive effect of various process parameters on the mélange yarn quality.

Estimation of yarn strength based on critical slipping length and fiber length distribution

Yarn strength is composed of the total contributions made by all breaking and slipping fibers which are determined by critical slipping length lc. Though the definition of lc has been the focus of many research projects, it still remains unsolved. In this study, idealized assumptions were made on yarn structure, and lc was then estimated. At the same time, the actual contributions that breaking fibers and slipping fibers make to yarn strength were recalculated based on an idealized yarn structure, which was analyzed with the conditional probability method according to fiber length distribution. Then, yarn strength was computed by simulating random fiber arrangement in the yarn. It could be seen from calculated results that the critical slipping length declines as yarn twist multiplier increases. Meanwhile, as the twist multiplier increases, the calculated yarn strength rises to the highest point and then declines, which is in agreement with traditional spinning theory. Thus, the calculation of yarn strength based on critical slipping length could reflect the yarn breaking mechanism with a change in the yarn twist multiplier, and could be applied for further prediction of yarn strength.

A novel method of yarn cross-sectional area calculation

Purpose This paper aims to study the yarn cross-section shape which is a very important yarn physical parameter and has a dominant effect on the physical structure of the yarn. Four factors affecting the yarn cross section, i.e. twist multiplier, Roving hank, spinning system and doubling technique, were investigated. Design/methodology/approach In past researches, the yarn cross-sectional area was calculated by considering any one yarn radius giving the approximate yarn cross-sectional area by assuming the yarn as a circular one. Findings In this study, a testing instrument is fabricated as shown in Plates 1 and 2 for yarn cross-section measurement and a novel method for calculating the correct yarn cross-sectional area of the yarn was developed. Originality/value In the past, no such studies have been conducted on the yarn cross-section studies because of the various limitations of the yarn cross-section measuring or testing instruments.

Study Effect of Twist Multipliers on Loop Length, Loop Shape, and Tightness Factors of Single Jersey and1×1Rib Knitted Fabrics

The study focuses on effect of twist multiplier on single jersey and 1 × 1 rib knitted fabrics loop length, loop shape, and tightness factors properties. For the study 100% cotton fiber which is processed into 40Ne (English count) carded ring spun yarn is used. Three twist levels of 900 turns/m, 1050 turns/m, and 1200 turns/m with respective twist multipliers of 3.6, 4.2, and 4.8 are used. The single jersey produced from the three twist multipliers is named as Sj1 which is produced from 3.6, Sj2 from 4.2, and Sj3 from 4.8. Similarly, 1 × 1 rib is denoted as R1 which is produced from 3.6, R2 from 4.2, and R3 from 4.8. The test was performed as per ASTM D1776-Practice for Conditioning Textiles for Testing. The tests done for ten specimens and the results showed that loop length, loop shape, and tightness factors properties of single jersey and 1 × 1 rib knitted fabrics are significantly influenced by twist multipliers variation.