OE-Rotor Spinning

The first functioning rotor spinning machine was presented at ITMA 1967. Yarn formation according to the rotor spinning principie predominates for aii noncon-ventionai spinning methods. Woridwide, more than 8 million spindles are in operation (Schindler, 2013). 

The fibers are twisted without stress between the pull-off nozzle and the rotor groove. The yarn twist is produced by the rotation of the rotor and the pull-off from the rotor and by a false twist at the pull-off nozzle. This false twist contributes significantly to the spinning stability and is removed again later (Eqs. 3.6-3.8). 

A technological characteristic of OE-rotor spinning is the presence of wrapper fibers (Fig. 3.19). When fibers are attached to the end of the twisted yarn in the rotor groove (a), they wind around the yarn end with one fiber end in the direction of yarn twist and with the other fiber end opposite to the direction of yarn twist (b-d). Such wrapper fibers, also called blurbs, are characteristic for OE-rotor yams. The resulting yarn appearance is attractive in some products, for example, blue Jeans. In other products, these wrapper fibers are unwanted. In yarns for cut-pile carpets, wrapper fibers are disadvantageous, as they prevent the pile from opening uniformly. 

With OE-rotor spinning, multiple different raw materials can be processed (cotton, wool under special conditions, flax as additive, chemical fibers, for example, viscose, polyacrylonitrile, polyester), and very different yarns can be produced. For different material and different yarn characteristics, the spinning elements, such as opening cylinder, rotor, and pull-off nozzle, have to be adjusted in shape and material. In spinning practice, a large number of spinning components are available on the market. 

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Figure 3.20 OE-rotor spinning machine (Courtesy of Schlafhorst)...

Similar to OE-rotor spinning, the yarns are directly wound onto cross-wound bobbins. Drawbacks compared to conventional spinning processes are the high investment and the difficult start of the spinning process. Another disadvantage is the removal of short fibers, hence only medium to long fibers are suitable for this process. At present, mainly 100% cotton or cotton blends with polyester are used. See Fig. 3.24 for an example of an air-jet spinning machine. 

With the nonconventional woolen spinning method, which was developed at the Institut fiir Textiltechnik at the RWTH Aachen, Germany, within a research project of the European Union, the slivers are produced on a novel compact card with only one tambour. They have a titer of about 4 ktex. Without additional roving formation, they can be spun directly into a yarn on a nonconventional woolen ring spinning frame or a modified OE-rotor spinning machine. 

Mule spinning machine I Ring spinning machine I OE-rotor spinning machine... 

Particularly from a quality management standpoint, control systems for the complete inspection of textile production within a spinning mill as well as open interfaces with suppliers and customers are necessary. Before the implementation of control systems, a phase model of the production process should be used to construct the textile production line and its partial processes. At present, these principles are already applied in OE-rotor spinning. The goal is to implement this processing strategy in the entire textile production process. 

Cotton yarns used for jeans are mostly manufactured from carded, uncombed cotton and spun on OE-rotor spinning machines. For especially high-quality jeans fabrics, the cotton may he comhed and spun on ring spinning frames. 

OE-rotor spinning 114 Opening and cleaning machines 99 Open-reed weaving 163... 

The yarns for jeans may he manufactured hy ring spinning. They will then have a higher degree of hairiness and tenacity compared to rotor-spun yarns. This makes the jeans more abrasion resistant in use. The production costs are higher than for OE-rotor-spun jeans yarns. 

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