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Abstract:
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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.
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