An Evaluation of Long- and Short-Term Variation in Sliver and Roving

Abstract

To study the effects of processing variables on product uniformity, a procedure for evaluating uniformity has been developed. Two types of variation, long- and short-term, are common in slivers, rovings, and yarns. It is shown here that short-term variation is a better indicator of the effects of processing variables than is either long-term variation or a composite of long- and short-term variation.

By measuring only short-term variation it was possible to: study the effects of doubling and drafting on product uniformity; develop drafting curves for the various drafting systems by which product variability may be predicted; and develop a formula for the comparison of the variation in unequal counts of roving and yarn.