Influence of fiber length and comber noil extraction in long staple worsted spinning on eri silk yarn quality

The eri cocoons are open mouthed and as their silk filaments are discontinuous, these can only be used for spun yarn production. In this study, the effect of fiber length and comber noil extractions on yarn quality were evaluated. The significant impact of fiber length as well as first and second comber noil extraction was observed on yarn unevenness, imperfections, tenacity, breaking elongation and hairiness. With the aim of minimizing unevenness, imperfections and hairiness along with maximizing tenacity and breaking elongation of yarn; the fiber length and comber noil were optimized using Minitab 19 software. It was revealed that 150 mm fiber length can be set in the staple cutter during spinning preparatory for all yarn counts; 19% and 7% comber noil extractions are required for first and second combing, respectively, to produce 40 and 60 Nm yarns, whereas for 80 Nm yarn about 1% more noil extraction is needed in both combing processes. Principal component analysis depicted that both two comber noil contribute about 57% and fiber length of 43% on yarn quality. Regression equations from the response surface design of the experiment were derived for different yarn quality characteristics which exhibit a difference between actual and predicted values of below 10%.