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Spinning Quality/Process Improvement Through Variance Tolerancing

Moon W. Suh, Jae L. Woo and Hyun-Jin Koo


 
ABSTRACT

The means and variances for yarn tensile strengths were derived for ring card (RSK), combed (RSC) and open-end (OE) spun yarns of varying sizes as a direct function of the constituent fiber length distribution, single fiber tensile properties and the "effective gauge length," L. A large amount of test data from a 3-year production experiment was collected in order to test the concept and validate the theoretical models. The effective gauge length L was estimated for each yarn studied and the estimated yarn tensile strengths were compared against the actual yarn strengths. By applying the "variance tolerancing" techniques, the total variance of the actual yarn tensile strength was decomposed into the between-package variance (24%) resulting from spinning processes and the within-package variance (76%). The latter, in turn, was decomposed into random component of the fiber properties (18%) and the nonrandom component (58%) that was process dependent. Effects of fiber length and strength on the resulting yarn tensile strength were also examined theoretically.



Reprinted from Proceedings of the 1997 Beltwide Cotton Conferences pp. 691 - 696
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998