Thesis Details

Thesis Title: Determining the relationship of sliver characteristics and combing roll settings on open-end yarn quality
Thesis Author: Kirk Nix
Abstract: Yarn producers have traditionally used the same open-end spin box settings on a variety of stock characteristics. Limited research has been published on the effects of the spin box settings on yarn quality given varying stock characteristics. It is the intent of this thesis to help yarn producers decide whether changes in stock characteristics delivered to the open-end rotor spinning machine warrant adjustments to certain spin box settings. To study the effects of different spin box settings on varying polyester denier and sliver bulk as related to yarn quality, a factorial design was used with two levels of each variable except combing roll speed, in which case three speeds were used. The levels for each variable were chosen so that they were wide enough to show significant effects and interactions, yet still be within practical processing limits: Yarn Count: Fiber Denier: Sliver Weight: Combing Roll Speed: Feed Tray Spacing: 24/1 and 39/1 0.7 and 1.2 dpf 35 and 45 gr/yd 6500, 7500, and 8500 rpm 0.3 and 0.7 mm Mid-tenacity,38mm staple DuPont Dacron polyester fiber was processed with the above specifications. The yarn was produced on an Autocoro open-end rotor spinning machine. Each of the forty-eight conditions were evaluated by the final yarn quality parameters included in the ITT Monthly Yarn Quality Program. An increase in combing roll speed resulted in decreased yarn strength. However, the faster combing roll speeds produced yarns with much lower defect levels. The highest combing roll speed used, 8500 rpm, produced better yarn when a 0.7 denier fiber was used, while a more moderate speed seemed desirable when the 1.2 denier fibers were used. The slowest combing roll speed, 6500 rpm, was generally undesirable. The feed tray-to-combing roll distance spacing was heavily dependent on the cohesion characteristics created by sliver weight and fiber denier. This research has shown that practical changes in polyester stock properties can drastically change final yarn quality. certain spin box adjustments had significant effects on the final yarn quality as well, proving that when stock characteristics are varied, changes should be made to certain spin box settings in order to maintain the highest level of quality achievable.