Rotor spinning has been characterized from the outset by incomparably higher production potential than ring spinning. This potential has been steadily increased by the continuous rise in rotor and winding speeds.
Rotor-spun yarns have therefore always been successful where they could be manufactured more cheaply than ring-spun yarns and proved suitable for the range of application in question.Rotor spinning combines two process stages – spinning and winding – in a single machine. Saleable cross-wound packages could therefore be produced immediately, without first having to wind small spinning cops. Integrated yarn monitoring systems and auxiliary devices for waxing the yarns at each spinning position also eliminate the need for a subsequent rewinding process. The production of rovings, which is required for ring spinning, is also eliminated, since the rotor spinning system is able to process carded or drawframe slivers directly.
Last but not least, the rotor spinning system has benefited from the fact that operator functions on the rotor spinning machine were much easier to automate than those on the ring spinning machine. Automation of all operator functions is now standard on high-performance rotor spinning machines, automated can and package transport is already an essential feature in many textile mills.
The technological challenge – not only when launching rotor spinning – has always been to separate the assessment criteria for rotor-spun yarn from the structural features of ring-spun yarns. The dominance of rotor-spun yarns, for example in woven denim fabrics and knitted fabrics, shows that this has been successful in some important end product segments. New ranges of application are still continuously being developed for rotor-spun yarns, on the one hand through selective modification of yarn properties, and on the other through continuous improvements in spinning stability.
The essential feature of the rotor spinning system is the separation of the functional stages of fiber sliver opening and yarn formation, respectively imparting twist and winding up the yarn. In order to achieve this the fiber bundle has to be interrupted at one point at least. This occurs between the functional stages of opening the drawframe or card sliver into individual fibers and subsequently combining these fibers in the collecting groove of the spinning rotor, the twisting device of the rotor spinning system. Since the individual fibers are released from a compact fiber bundle during transport between the opening roller and the rotor collecting groove and are only combined again in the rotor groove, we can here refer to an open yarn end.