A Study of Lea-Strength Variation of Ring-Spun Cotton Yarns

Abstract

The findings from an investigation to identify the contribution of factors that affect lea-strength variation are presented. The within-bobbin strength variation is more or less independent of the within-bobbin count variation, so that this component of strength variation can be regarded as arising largely from inherent testing errors. However count variation is the major contributor to between-bobbin strength variation. The actual contribution of count variation to strength variation decreases as the level of twist in the yarn is increased, a fact which is explained on the basis of the well-known shape of the twist-strength curve. Different methods for isolating the effect of count variation on between-bobbin strength variation were tried. Analysis of covariance was found to be a suitable technique for this purpose. This technique was used to identify the factors that contribute to the residual strength variance that is the variance left unaccounted by count variation. An interesting finding in this regard is the fact that even wide differences in preparatory processes do not by themselves lead to significant differences in the residual variance if the materials from these processes are spun in isolation.