Shortening the technological spinning processes, aiming at the reduction in production costs, causes problems with keeping up a high quality of yarn. Of great significance is the use of autolevellers that not only equalize the distribution of fiber linear density but also straighten the fibers and lay them parallel to the product axis. Consequently, they replace the machines eliminated from technological lines and contribute to the improvement in the quality of intermediate products and yarns. Using an example of the cotton combed spinning system, the article presents the analysis of the possibilities of using a short-term autoleveller with a modified operation algorithm that takes into account the phenomenon of sliver retardation after the process of short-term regulation. The regulation of draft was used before and after combing. The quality parameters of slivers used for feeding roving frames or rotor spinning machines were analyzed.

During the technological processing of staple fibers into yarn drafting, waves are formed which increase the irregularity of yarn linear density and consequently affect the yarn quality. Even a correctly performed technological process does not allow one to completely eliminate yarn faults (thin and thick places, neps) and yarn irregularity. All the yarn imperfections distinctly become apparent in flat textiles made of such a yarn. The quality of the yarn produced should be assessed already in spinning mill, using the results obtained to conclude on the quality of woven or knitted fabrics. Modern metrological laboratories in spinning mills possess Uster Tester 5 (UT5) apparatuses that not only assess the yarn quality with respect to the irregularity of linear density, faults (thin and thick places, neps), or hairiness, but also using the test results obtained make it possible to create a digital image of the predicted appearance of a flat fabric made of the yarn tested. This article presents a computer-aided method of the analysis of the woven and knitted fabric images obtained from UT5 that allows one to assess the significance of particular yarn parameters in the predicted appearance of flat fabrics.

The paper presents assumptions for the fiber movement model in the drawing mechanism field, aiming at establishing a regulation equation with a modified operation algorithm of the short-term draft regulator of slivers made of staple fibers. The model takes into account the sliver retardation phenomena and makes it possible to increase the evenness of slivers feeding successive machines in the technological process. As a result of this, the evenness of yarn will be increased contributing to an improvement in the quality of flat textile fabrics. This model, despite simplifying assumptions, sufficiently precisely presents the phenomenon of reducing the effect of drawing waves on the distribution of the linear mass of the fiber stream.