Thesis Details


Thesis Title: The Identification and Quantification of the Factors Responsible for Generation of Cotton Yarn Fly on a Circular Single Knitting Machine
Thesis Author: Robert W. Slate, Jr.
Abstract: Fly is short, waste fiber released by the yarn during processing. Especially prone to generate fly are natural fibers such as cotton which cause serious problems in knitting plants by building up on the machinery during normal operation. The fly detaches from the main body of the yarn during processing and is released into the air, often attaching to the knitting machine. A sufficient accumulation of fly on the knitting machine interferes with the passage of yarn through eyelets, guides, or tubes and restricts the movements of needles and sinkers. It then often causes a malfunction of the machine or breakage of the yarn. Fly has been found to account directly for as much as 50% of total unscheduled machine stops. It is also indirectly responsible for many other stops as well as fabric defects. The problems caused by fly add to manufacturing costs by increasing labor requirements, production machinery requirements, fly control equipment, and replacement part usage. The fly producing sections of the creel, yarn furnishing units, and the stitch forming zone of the knitting machine were isolated by collection compartments. The effects of package taper, different yarn furnishers, and different stitch lengths were determined through measurement of the amounts of fly generated by ring, open-end, air jet, and friction spun yarns. At the creel section, ring spun yarns generated the most fly of any spinning method tested. Air jet yarns produced the least amount of fly. Yarn processed on straight sided tubes generated 183% more fly than the yarn processed on go 15' cones. Tapered cones were found to significantly benefit ring spun yarns only. At the yarn furnisher, an increase in the amount of tension on the yarn or the number of wraps around the spool increase fly production. Also, ring yarns generated more fly than any other spinning method tested. At the stitch forming zone, ring spun yarns generated significantly more fly than open-end, air jet, or friction yarns. Combing significantly reduced fly production at the stitch forming elements. An adjustment of the stitch cam setting from a course length of 160.84 inches to a course length of 203.32 inches increased fly generation on ring and air jet spun yarns. The knowledge generated about fly formation at knitting was used to identify a practical means of control. The method identified integrated the yarn furnishing units into the yarn package creel and provided each knitting position with a suction unit. Tests of the unit revealed that approximately 90 percent of all generated fly can be both controlled and captured.