Effects of Selected Micronaire Levels of ‘Acala 1517’ Cotton on the Quality of Ring and Open-End Yarns

Bales of a genetically fine-fibered cotton, 'Acala 1517', were blended at micronaire levels of 3.0, 3.3, 3.9, and 4.4 to make lots for mill processing. Tests were conducted on each lot to determine the fiber properties of raw stock and finisher-drawing sliver, the opening, picking, and carding wastes and nep contents of processed cottons, and the properties of ring and open-end yarns. Variations in the fiber properties of raw stock for the four selected micronaire levels were small. Variations in fiber properties were greater for finisher-drawing sliver than for raw stock, reflecting the different effects that processing has on fibers of varying maturity. The micronaire levels of finisher-drawing sliver were higher than those of corresponding raw stock, apparently a result of breakage and subsequent removal of the low-maturity (low-micronaire) fibers as waste during processing. From a practical standpoint, opening, picking, and carding wastes were similar for the four micronaire levels, although the waste level was significantly lower for the 3.3-micronaire, cotton. Card neps were highest for the 3.0-micronaire cotton and lowest for the 4.4-micronaire cotton. The effects of micronaire level on processing and yarn quality were more pronounced for the ring yarns than for the open-end yarns. For the ring yarns, as micronaire level increased, spinning end breakage increased, strength decreased, elongation decreased, evenness remained the same, wet-processing losses decreased, and dyeing quality improved. With the exception of dyeing quality and wet-processing losses, the performances of the 3.0- and 3.3-micronaire cottons were equal or superior to those of the cottons inside the premium micronaire range (3.5 to 4.9). Therefore, cottons with micronaire levels outside the premium range may perform equally as well as those inside the premium range. In this study, differences in micronaire levels inside the premium micronaire range caused significant differences in processing and yarn quality.