Factors Affecting Rotor Spinning of Fine Cotton Yarns

To examine some of the challenges of extending rotor spinning to finer cotton yams, we performed a set of experiments combining five factors: fiber type, presence or absence of combing, sliver weight, yarn count, and twist level. We assessed processing behavior by the end-break rate, using a BD200S rotor spinner, and yam quality by tests of evenness, single-end tenacity, and appearance. The design of the combined experiment was sensitive to interactions of these factors. Compared with control con ditions (spinning carded sliver of a coarse stripper cotton with a sliver weight of 4.2 ktex at weaving twist to a yarn of 30 tex ), trials with other combinations yielded several significant interactions. At the finest count (13 tex), the experimental cottons, notably the low micronaire variety, were all more spinnable than the fiber typically used in rotor spinning. Combing lowered end-break rate by a factor of approximately 3.5 under most conditions and improved yam properties. Reducing draft by halving the weight of input sliver reduced end-break rate appreciably for all except the control cotton, but had little effect on yam properties. The lower (knitting) twist was not feasible when using a four-groove navel with the shorter cottons, but it improved yarn evenness. This favors knitting over weaving yarns at fine counts. The longer staple cottons showed less need for a higher twist, but had poorer fiber strength utilization at all twists.