Thesis Details

Thesis Title: The Effect of Draft Distribution, Roll Spacing, Denier, and Blending Method on Air-jet Yarn Quality and the Formation of Classimat Long Thins
Thesis Author: Dean Cobb
Abstract: Since the introduction of the Murata Jet Spinner in 1981, numerous researchers have studied the air-jet technology and how to optimize the spinning parameters and conditions of the machine. However, when the Murata Model 802 was developed, the goal was to increase the total draft capability by expanding the draft zone to the four roll system. Now a five roll system has been introduced to increase draft even more. The questionable aspect of these draft systems with additional drafting zones centered on the lack of flexibility in the break draft zone. To date, no published work has been done to show that the standard Murata break draft of 2.00, for the four and five roll systems, yields the best quality. This thesis investigated break drafts of 1.54, 1.82, 2.00, 2.22, and 2.50 and determines whether the current machine's parameters were the best in all situations when yam quality is considered. Along with various break drafts, this research incorporated two types of polyesters which have different deniers. The deniers were 1.2 and 0.9. The use of a microdenier fiber would increase the amount of cohesion in the sliver by allowing more fibers in the crosssection. The increased cohesion was intended to provide better fiber attenuation regularity while subjected to the high levels of break draft. The effect of back zone roll spacing was another objective for this work. As discussed previously, the distance between rollers in a drafting zone was critical to how fibers will draft. This thesis investigated the standard setting of 42 millimeters and a wider setting of 46 millimeters to evaluate how decreasing the required drafting force affects yam quality. Finally, intimately and drawframe blended 50/50 polyester/cotton slivers were processed to determine if the distribution of the polyester and cotton fibers in the slivers affects yam quality. To accomplish this research, forty conditions were spun according to the variables presented above. The nominal yam count for all conditions was 35/1 Ne. The yam was then tested and ranked according to the members' air-jet yams of the same count and blend on the Monthly Yam Quality Control and Calibration Program. With respect to the objectives of this thesis, the following conclusions were derived: 1. Draft distribution did impact the quality of air-jet yarns. For optimum yam quality, the break draft's intensity must be comparable to the cohesive forces within sliver. 2. Back zone roll spacing prove to be a primary factor where long thin formation and overall yam quality is concerned. The data gathered supports that shorter distances between rollers improves yam quality which is contributed to the high degree of fiber control exerted on the fibers. 3. Each polyester denier proved to be both good and bad. For instance, the 0.9 denier fibers contained more cohesive forces which increased fiber control in the higher drafts and with wider roll spacings. However, the cohesion in the 0.9 denier sliver was strong enough that yam quality processed in the lower break drafts and the 42 millimeter roll setting diminished due to lack of fiber individualization. The 1.2 denier proved to be the best overall despite its inability to withstand the higher break drafts. 4. Intimate and drawframe blending methods impacted various yam quality parameters. The success of the drawframe blend can be attributed to the excellent performance of the Rieter C-10 card used for the 100 percent cotton carding. Although the intimately blended slivers did not hold the best sliver quality ,their uniform distribution of fibers throughout the sliver cross-section did allowed for less variability in some yam characteristics.