Effects of Fiber Opening on the Uniformity of Rotor Spun Yarns

We have studied the dependency of rotor spun yam uniformity on variations of rotor speed, opening roller speed, and twist level. The number of points per fiber (ppf), which reflects the level of fiber opening, is useful in evaluating the effects of spinning parameters on yarn uniformity. Experiments based on a 60 tex yam indicate that the properties of yarn unevenness and incidence of imperfections improve as ppf increases due to improved fiber separation. A critical value of the ppf is identified for CV% values and other measures of imperfections. Beyond this critical value, further increases in the ppf do not lead to any significant improvement in those yam properties. This is due to the high level of fiber breakage at high ppf values.