Twist requirement for blended yarns

The twist requirement of a yarn is defined by not only the number of twist turns per unit length of the yarn (T) but also the yarn diameter, which can be related to the yarn linear density (C) by assuming a constant yarn volume density. For yarns consisting of a single type of fibre, for example, pure cotton yarns, the twist requirement is commonly specified by the twist factor . For a blend of fibres with extreme difference in volume densities, for example, a blend of cotton and stainless steel fibres, the blended yarn volume density varies dramatically with the blend ratio, and the relationship between twist, yarn linear density and twist factor has to be adjusted accordingly. In this paper, we introduce a formula of equivalent yarn linear density that is simple to use for determining the twist requirement of blended yarns. The formula was used to calculate the twist settings required for the whole range of cotton/stainless steel fibre blend ratios to achieve approximately the same twist angle in the final blended yarns.