Thesis Details

Thesis Title: An evaluation of the effect of card waste extraction on ring, open end, and air jet cotton spun yarn
Thesis Author: Christopher Davis
Abstract: For the past few years, the yarn manufacturer has experienced many technological advances that has enabled the spinning of cotton yarns at higher delivery speeds. However, to reap the benefits of these increased speeds, a cleaner fiber stock with better fiber characteristics is needed. A popular method of achieving this level of cleanliness is by processing cotton fibers through the combing process. However, this is a costly process that is reflected in the price of the yarn. Previous research has shown that changing carding parameters such as cylinder speeds, licker-in speeds, and production rate, improves the cleanliness of carded stock, because of increased cleaning efficiencies and waste removal. It has been shown that as the amount of trash in finisher sliver reduces, fewer ends down in spinning occur, therefore enhancing the quality of the yarn. This research was undertaken to explore how increased levels of waste extraction under the licker-in affected the quality of cotton carded yarns. These carded yarns were then compared to a combed yarn with 2-3% short fiber, to determine if combed quality could be achieved by a carded yarn. To accomplish this, three levels of waste extraction at the card were obtained: low (2-4%), medium (6-8%), and high (10-12%). For this research, the low level of waste extraction represented the level currently being used in industry today. The medium waste extraction level of 6-8% was twice the industry average and was considered extremely high. The high waste extraction level of 10-12%, was three times that of industry average. cottons from two growth areas were used to make three processing stocks, California, Memphis, and 50/50 California/Memphis cotton blend. A finisher sliver was produced and channeled to ring, open end, and air jet spinning systems, where a 30's yarn was spun from the three waste extraction levels and cotton types. A series of tests were performed on each finisher sliver condition to determine what effect increased levels of waste extraction had on fiber characteristics in the sliver. The yarns spun were then tested and ranked according to the Institute of Textile Technology's MQC program. The results of these tests revealed that short fiber and trash content were reduced as waste extraction moved to the medium level. However, in many cases, advancing to the high level of waste extraction did not provide further improvements because of the methodology used in extracting the high level of waste. Several benefits resulted from above average (2-4%) levels of waste extraction. Yarn appearance was improved from a B- to a B, and Uster %CV was reduced from 0.5 to 1.0 percentage points. The number of Uster thin, thick, and neps per thousand yards were also reduced. Improvements in these yarn properties occurred because of reductions in short fiber and trash content. Based on this research, very few carded yarn properties approximated that of a combed yarn. However, single-end strength (g/tex) of carded ring yarns were equivalent to the combed yarns produced. Uster %CV and Uster thin places for open end and air jet yarns approached the combed yarn level of quality. Also, Uster neps/1000 yards for carded air jet yarns were equivalent to the combed air jet yarns. In this research, only a few carded yarn properties were comparable to the combed yarns produced. However, by increasing waste extraction to levels considered above industry average (2-4%), many improvements occurred in the carded yarn quality ring, open end, and air jet yarns. These improvements, along with a fiber reclamation process, could help the yarn manufacturer spin cotton yarns more efficiently and effectively.