Determination of Twist Coefficient of Core-spun Yarn

The strength of the core yarn decreases with the increase of the twist coefficient, because the strength of the filament decreases with the increase of the twist coefficient. When the cotton content is less than 50%, although the strength of the outer short fiber increases with the increase of the twist coefficient when the twist coefficient is within the critical twist coefficient, the former plays a major role, so the twist coefficient of the core-spun yarn should be kept low. However, the twist coefficient of the polyester-cotton core-spun yarn used for burnt-out fabrics should not be too small, generally controlled at about 304-333, so as to avoid the filaments of burnt-out parts from being uncomfortable. The twist coefficient of the spandex core-spun yarn is 20-30 higher than that of the ring-spun pure cotton yarn of the same variety (referring to the warp or weft yarn) and the same count (number), so that the yarn strength of the two is close.