FRICTION SPINNING

1.2 Background of the Invention Up to the late 1960s, almost all yarns made from staple fibres were produced on the ringspinning system. However, spinners were becoming increasingly aware of the fact that low productivity was inherent in the basic principle of ring spinning. Spindle speeds reached a maximum, rotating rings began to be used, and automatic-doffing systems and new rings and travellers were developed. Despite all these advances, the system had reached a plateau with regard to the maximum production speed. These technical and economic limitations of conventional ring spinning had been the subject of much discussion, and, as a result, machine makers and research institutes were on the lookout for new and future-oriented spinning technologies. The aim of most of these new technologies was to increase productivity, improve or at least retain yarn quality, and ensure increased efficiency in subsequent processing [1]. It was in 1967 that the aim became a commercial possibility with the introduction of the BD-200 rotor spinner, which did away with the concept of spindle-twisting. Since then, the rotorspinning system has estabhshed itself in the coarseand medium-count range. However, as the rotor speed was reaching 150 000 r/min, the rotor diameter had to be reduced to around 28 mm to accommodate such a high speed. It was therefore felt that this system had also reached its practical limits with regard to productivity. Thus the search for other spinning systems continued. New systems, such as twistiess spinning, air-vortex spinning, and selftwist spinning, made their entry in the late 1960s. In 1973, the friction-spinning system was developed by Ernst Fehrer. It was commercialized in 1977 under the name DREF-2. In this system, the spinning speed is as high as 300 m/min and is not limited by the yarn tensile forces. Theoretically, very high rotating speeds are attainable.