EFFECT OF COTTON PREPARATION ON AFIS AND HVI MEASUREMENTS
J.L. Simonton, W.D. Cole and P. Williams
International Textile Center
Texas Tech University
The basic purpose of this study is to examine the use of the AFIS and the HVI to improve performance of the spinning process. Since the various mechanical processes modify the state of the fibers, we must first determine the effects of fiber preparation on instrument readings.
Cotton processing machines that mechanically work the cotton fiber from bale to yarn are designed with the intent of minimizing fiber damage. Nevertheless, opening, cleaning and blending equipment shorten the staple length while increasing short fiber content and neps. Carding and combing reverse this by removing a percentage of the short fibers and neps. Drawing is thought to have a minimal effect on fiber physicals, its purpose being to improve sliver evenness and fiber orientation.
With machine settings and speeds optimized, a comparison of the fiber properties of stock-in compared with stock-out provides valuable information for achieving further optimization.
Instrument used: Uster AFIS and HVI Spinlab 900B
No. of bale samples: 10 bales with different mic and length were used
No. of processing method : 12 different processing combinations
hunter hopper feeder
Rieter Mono cylinder (750 rpm)
Rieter ERM B5/5(850 rpm)
Rieter ERM B5/5(950 rpm)
Rieter C4 card with Hollingsworth Trashmaster TM2000 (100 pounds per hour, with 60 grains per yard sliver)
Saco Lowell Rovematic FC-1B
Ring spinning: Saco Lowell SF-3H
Open end machine: Schlafhorst Autocoro
Predrawframe for comber: Saco-Lowell DE-7C
Lap former : Rieter Unilap E5/3
Comber : Rieter E7/6
DETAILS OF THE FINDINGS:
There are slight AFIS variations in the apparent fiber diameter when going from a processing stage to another. It seems that the ERMII results in a slight increase, which could be due to the removal of dead fibers in the opening line. Certainly the card also removes neps and dead fibers; however, the diameter appears to decrease slightly (Figure ) There is also a significant decrease due to the drawing. These mechanical processes cannot modify the diameter. The only logical explanation is an artifact effect. In the card sliver and the drawing slivers the fibers are oriented and paralleled, this removes the crimp. The length of the electronic signal and its height are then modified giving higher length readings and lower diameter readings.
The HVI micronaire values (Figure 1) vary slightly in the opening line, perhaps due to the removal of some dead fibers. The carding seems to reduce the micronaire, which is not explainable. Then the drawing leads to an increase in micronaire. The theory of the micronaire instruments is based on airflow passing through a sample constituted of randomly oriented fibers. In the drawing process the fibers are made parallel, which probably leads to an easier flow of air through the cotton sample and results in an apparent higher micronaire.
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