The Rating of Yarns for Short-Term Unevenness

Abstract

Two surveys for unevenness were conducted between 1956 and 1960. They covered yarns spun on the worsted and on the cotton systems. They provide a broad picture of the unevenness of yarns produced commercially in Canada and in some other coun tries. Because of the wide coverage, the yarns are considered to be representative of spinning on the worsted and cotton systems. A total of 438 yarns were included, 282 of them spun in 62 Canadian mills, and 156 yarns coming from 55 mills in ten other countries. Of the 438 yarns, 104 were worsted, 151 carded cotton, 69 combed cotton, and 114 man-made fibers. A large range of counts were covered, from 310 to 7.6 tex. Short-term unevenness was found to vary greatly from yarn to yarn. A major factor in this variation is the count of the yarn ; finer yarns tend to be more uneven. Both the unevenness as measured on the unevenness tester and a calculated "index of unev enness" (based on Martindale's "random" unevenness) depend on yarn count. A modified index, the Unevenness Level, was developed. It eliminates the influence of yarn "size" (that is, of yarn count and of fiber fineness) and can serve to rate the "spinner's per formance." It is a modification of the index of unevenness and is based on a Poisson model intermediate between Martindale's and Temmerman's. It is proposed for the rating of varns spun on the cotton and on the worsted systems.