A statistical and Taguchi process analysis as applied to cotton fiber properties and white speck occurrence



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Cotton containing immature fibers is a major concern in the dyeing and finishing of textile products. In an un-dyed state, entangled fiber clusters are generically classified as neps. It is only after the application of dye, when some neps remain un-dyed, that the more specific classification of “white speck” is used. The High Volume Instrument (HVI) fiber property measurement system is important in marketing and general quality assessment of the cotton crop; however, HVI is not precise enough to address immature fiber content. The purpose of this research was to examine the relationship of Advanced Fiber Information System (AFIS) fiber properties to white speck counts of dyed yarn. This research looks at three sequential studies. First study looked at the within and between bale differences while establishing a regression model for white speck count and AFIS fiber properties of bale cotton and sliver cotton. Ten bales of cotton with a range of micronaire were sampled (10 samples per bale) and analyzed using AFIS with 3 replications of each counting 3,000 fibers. Each sample was then processed into yarn and dyed using the same procedure. White specks were quantified on dyed yarn using a white speck yarn counting method. Regression results indicated that fiber fineness, nep per gram, and immature fiber content found to be the influential indicators of white speck count in dyed yarn. However, small sample size and possible AFIS bias in the fineness and maturity measurements requires a larger sample size for further investigation. Second study analyzed the relationship between AFIS fiber properties and yarn white speck count by using statistical analysis. The treatments of harvest-aid chemical termination with varied harvest dates and two levels of field cleaning were included. Cotton samples of two crop years were sampled and analyzed using the AFIS with 3 replications, each counting 3,000 fibers. Each sample was processed into yarn and dyed with the same procedure. White speck counts on the yarn for each sample were conducted utilizing a white speck yarn methodology. The harvest date treatment influenced white speck count more than other fiber properties. The nep count by weight fiber property was also found to be one of the predictors of white speck count. However, the prediction model was not found to be as strong as the first study. Third study is the application of Taguchi method on the second study. Taguchi method is used to investigate the minimum white speck count in dyed yarn through fiber properties of varied harvest techniques. Signal-to-noise ratio (S/N ratio) was used to represent a response variable of white speck count. The smallest S/N ratio was chosen for this study. Among the control factors, harvest date, defoliation and field cleaner, the harvest date was found to be the significant effect on the S/N ratio of white speck count. The desirable outcome for white speck response was found to be early season harvesting and application of field cleaning and defoliation. By removing smaller, less mature bolls at early harvest date with field cleaner reduced the white speck count.



White speck, Cotton fiber properties, Taguchi, Regression