A Computer-Based System for Evaluation of Slub Yarn Characteristics

This research aims to build a computer-based system for measuring slub yarn characteristics and evaluating the results using statistical methods. The measuring system was based on the electrical condenser of the Uster evenness tester as a measuring sensor. A digital storage oscilloscope was used to convert the analogue output signals into digital data to be recorded on a computer. A designed computer program was constructed using MatLab language for signal analysis based on a proposed method. Final results from this system contained graphical plots for the three measured slub yarn geometrical parameters slub length, slub distance, and slub thickness and a final report for all the measured slub yarn characteristics. The results of tested slub yarn samples showed that actual slub geometrical parameters differ from nominal values and the difference had two level: prevailing difference and outlier values. Outliers which are considered slub yarn defects were detected and counted in a final report using the box plot statistical method which could be an effective industrial tool for evaluation of both yarn quality and machine performance. The prevailing difference was assessed using histogram comparison which could help in adjusting the setting of slub yarn device to obtain the required appearance. 1. Introduction Ground slub yarn is a simple fancy yarn whose slub appearance is gained by the variation of yarn linear density during spinning process and no additional yarn or process is required. It is used to produce an acceptable handle and fancy appearance mainly for plain conventional fabrics. Slub yarns could be produced by modifying ring spinning frame, such that the intermittent acceleration of the rollers will cause varying degrees of draft to be applied [1]. The programmed electronic control of two or more separate variable speed motors for each drafting roller enabled leading companies to produce such new drafting systems to obtain a wide range of slub yarn characteristics. Evaluation of slub yarn characteristics which are different from conventional yarn is very important in the slub yarn manufacturing process as they determine the final appearance of the produced fabric. The traditional manual measuring method based on the black board and using standard measuring scales is time consuming. Different methods for measuring slub geometrical parameters, that is, slub length, slub distance, and slub thickness, were introduced in recent researches. Sudhakar [2] used and compared between different methods for measuring slub geometrical parameters. Slub length