Prioritizing the quality parameters of cotton carded knit yarn by varying tensions of the bottom aprons of the ring frame

Abstract

The forces exerted on fibres during drafting in the drafting zone with the upper and bottom aprons of the Ring Frame significantly impact the yarn quality. Aprons are crucial in manipulating fibres by facilitating movement and directing them toward the primary drafting area. From these two aprons, the bottom apron's tension is changed by changing tension spring bar groove hole positions. There is no scope for changing such settings in the case of top aprons. This research aims to achieve high-quality cotton carded knit yarn by selecting an appropriate bottom apron tension due to the significant role in proper drafting and twist insertion at the time of the manufacturing process directly affecting produced yarn's strength, evenness, imperfections, and hairiness properties. To fulfil this requirement, six yarn samples are produced each time by using 5 different tensions of the bottom drafting aprons. The samples underwent quality parameter testing, including Unevenness (U)%, Coefficient of Variation (CV)%, Imperfection Index (IPI), Hairiness (H), and Count Strength Product (CSP). The findings indicated that increasing the tension of the bottom apron while maintaining positions 1, 2, and 3 reduces the occurrence of neps, variations in thickness and thinness, and imperfections. In contrast, CSP is increased due to elevated stress on the fibres. In general, maintaining an appropriate tension enhanced the quality of the yarn, and the best quality was obtained for position 3, considering all the quality variables. Moreover, by using Interpretive Structural Modelling (ISM) methodology, the pairwise relationship between the quality variables is shown. Finally, after calculation, those quality variables are arranged in three levels. According to this level, the quality parameters are ranked where the top is the highest. It is observed that Count Strength Product is at the highest level, which indicates that CSP should be given more priority. Moreover, the end use of this yarn is to produce knit items, and for the knitting yarn, CSP is one of the most influential quality variables.