Determining the Cross-Sectional Packing Density of Rotor Spun Yarns

Abstract

Packing density, the fiber distribution in a yarn cross section, can to a great extent influence the properties and quality of the yarn. Thus, the need for precise and concise information about packing density becomes a must for an in-depth understanding of yarn structure and hence yarn mechanics. This paper describes a detailed method for determining packing density. We begin by acquiring yarn cross-sectional images to provide input data for calculating yarn cross-sectional packing density. These data include the coordinates of each fiber center and fiber radius. A program whose general writing algorithm is also elaborated in detail is compiled to calculate the packing ratio zone by zone. With these discrete packing ratios, a curve-fitting technique yields a continuous packing density function. In addition, a study of the relationship between packing density and yarn parameters such as yarn count and twist factor is included.

A study of the fiber distribution in yarn cross section for vortex-spun yarn

“…The maximum packing density is within the yarn radius of 0.031 mm, and then it gradually decreased from its core to its surface, which is very similar to other yarns, such as compact yarns, rotor yarns and Murata Jet Spinning (MJS) yarns. 1,11,16 From Figure 3, it can be shown that the vortex-spun yarn has lower fiber packing density value than that of conventional ring-spun yarn at the yarn center and surface. It may be identified that the radial pressure action on the core fibers of vortex-spun yarn, produced by the high-speed whirled air current, is lower than the radial pressure action on the central fibers of conventional ring-spun yarn, produced by the mechanical twist motion in a triangle zone of spinning.…”

“…The effective yarn diameter D ef obtained from the fiber packing density distribution was considered as the best value representing the real yarn diameter. 1,11 The effective yarn diameter D ef can be obtained according to the fiber packing density value of 0.15 from the fiber packing density distribution curve. 1 That is, the outer diameter of the radial ring, where the fiber packing density distribution is equal to 0.15, is the effective yarn diameter D ef .…”

Study of fiber packing density of lyocell ring‐spun yarns

“…Although some researches are concerned with ideal packing density, but because the yarn structure is quiet disordered (Hearle, Grosberg, & Backer, 1969;Petrulis, 2003), most of the researches are limited to calculating this factor for yarns made of circular fibers (Jiang, Hu, & Cheng, 2005;Neckar, Ishtiaque, & Svehlova, 1988). In this paper, a new method based on image analysis is introduced that does not have any limitation with regard to fiber cross-sectional shape.…”

“…In some recent researches, the effect of some variables such as yarn count, twist factor, lap hank, card draft, draft doubling and draft at speed frame, ring frame and rotor and air jet spinning on the fiber packing density has been analyzed (Jiang et al, 2005;Kumar, Ishtiaque, & Salhotra, 2006). Yilmaz, Goktepe, Goktepe, and Kremenakova (2007) have analyzed the effect of type of compact spinning machine on the fiber packing density.…”

Fiber packing density in the cross-section of low torque ring spun yarn

“…9,10 However, a number of experiments revealed that the radial packing density of staple yarn is non-uniform. 13–18 Based on the assumption that fibers are arranged in the form of concentric helices in a yarn, Hearle et al. 10 introduced the second approach to analyze fiber packing density by dividing the yarn cross-section into several annular zones.…”