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Abstract:
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Seventy percent of yams produced are converted into woven fabric. Considering the
increasingly demanding requirements placed upon the yams by technological developments,
now, more than ever, yam quality is critical to weaving machine productivity. Modern
weaving machines are capable of producing high outputs. To reach maximum machine
productivity, yams must process efficiently at high speeds. Tensile variation in the yam is
an important factor that may limit weaving machine productivity.
The primary purpose of this work was to investigate differences in warp yam
performance by examining tensile test data. In this research, two tensile testers, the Tensojet
and Tensorapid were compared. Both testers were .developed by Zellweger Uster, a Swiss
based company specializing in textile testing. The Tensorapid is a standard tensile tester
currently used in industry. The Tensojet is a high speed tensile tester that allows a
comparatively much larger sample in a reasonable time. Since past research has shown large
sample test data is the best indication of subsequent processing performance, the Tensojet
data was used to predict differences in warp yam performance. Yam quality measurements
were used to provide further insight into differences in yam performance. This work also
sought to provide insight into the relationship between weaving machine settings and Tensojet
test results.
The results of this work showed a difference in results between testers based on test
speed and sample size of the test. Compared to· weaving performance, tensile results did not
necessarily predict differences in warp yarn performance. On the other hand, calculation of
the lowest tensile values based on Tensojet and Tensorapid data below a critical limit corresponded with weaving performance. When yarn tensile strength and elongation results
fell below these limits, weaving performance showed an increase in warp yarn stops. Since
a comparatively large number of yarn imperfections corresponded with weaving
performance, imperfections seem to increase tensile variability and reduce weaving
performance. The machine settings used in this research had no affect on warp yarn
performance. Considering experimental limitations, and with respect to the objectives of
thesis, the following general conclusions were derived:
1. The higher test speed of the Tensojet resulted in an increase in average strength
results. Differences in variabilities measured by both testers may have been affected
by either test speed or sample size. As the speed differential between the two testers
was reduced, the relationship between testers was strengthened.
2. Neither the machine speed nor shed length ~sed in this research affected warp yarn
performance.
3. Tensile values below a critical limit correspond closely with weaving performance.
(a) While differences in tensile limits did not necessarily indicate weaving
performance, tensile limits below a critical limit corresponded with a
difference in weaving performance.
(b) For tensile limits, the traditional sample size of 200 breaks was large enough
to show the important differences among yarns with respect to weaving
performance.
4. The Tensojet scatter plot was the best predictor of warp yarn performance because the
sample was large and the weakest strength and elongation values were considered
simultaneously.
5. The trend is for high tensile variability to follow weaving performance.
6. An increase in short-term Uster %CV followed high tensile variability and weaving
stops. The trend is for a large increase in mass variation to follow tensile variability.
As the amount of mass variation is increased, the probability of weak places that
could result in weaving stops increased.
7. The analysis of imperfections and defects followed closely the analysis of Uster CV.
A large number of imperfections and defects corresponded to a reduction in weaving
performance.
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