Thesis Details

Thesis Title: A comparison of a newly developed on-line acoustic sliver monitor versus the ITT sliver analyzer for recognition of defects in 100% cotton card sliver
Thesis Author: Oliver Sommer
Abstract: Defects which exist in card sliver have been shown to result in yarn defects which are costly to yarn and fabric producers. Currently, monitoring card sliver for defects is a labor intensive process which interferes with product flow and provides information only on a small percentage o f actual card production. An on-line method of monitoring sliver quality would provide opportunities to improve yarn quality and the effective management of the carding process. Recent advancements in computer and sensor technology have made the development of an on-line test method for the detection of sliver defects possible. The Qualteq Acoustic Sensor is a newly developed sensor which determines sliver weight by measuring the noise created as sliver passes through the trumpet at carding and drawing. Information provided from this sensor is currently being used to determine sliver weight, weight variability, detect periodic defects, and calculate machine efficiency at the carding and drawing processes. The Acoustic Sensor has several advantages over sensors currently being used to measure sliver weight on-line. These advantages include the lack of moving parts, the ability to withstand harsh production environments, and the passive which it employs to measure sliver weight. It is also easily retrofitted to production equipment. It produces an signal which is extremely sensitive to changes in sliver weight and easily converted into usable information. It was the purpose of this thesis to determine if the Qualteq Acoustic Sensor could also be used to detect u l trashort term defects in card sliver on a real-time basis . The defects under investigation included slub type defects which are usually under 2 centimeters in length and coarse trash . Both of these defects have been shown to adversely effect yarn quality. Sliver defects are abrupt increases in sliver density which exist in sliver. Most sliver slubs originate at the carding processes as a result of improper operating conditions. The Acoustic Sensor was capable of detecting slub type defects in card sliver which were greater then 115% of normal sliver weight. The sensor was also capable of providing information on both the density and length of the defect. A direct correlation existed between slub levels recognized by the ITT SLiver Analyzer and the Acoustic Sensor. Results from the coarse trash trial have shown the Acoustic Sensor to be an excellent tool in determining trash levels in card sliver, which is an indication of a mechanical condition. The ability to monitor trash levels exiting individual cards twenty-four hours a day, seven days a week, will provide valuable insight into the wear patterns of card wire and other vital card components. Cards which were determined to be high in sliver defects by the Acoustic Sensor produced yarns which were of inferior quality to yarn produced exclusively of quality sliver. The major effects on both ring spun and open-end spun yarn were on breaking strength and Classimat defect levels. Once fully developed this application of the Acoustic Sensor will provide yarn manufacturers with vital quality assurance information on every inch of card sliver produced. Thus allowing for the isolation of individual cards producing off-quality sliver which adversely affects yarn and fabric properties.