Determining the Cross-Sectional Packing Density of Rotor Spun Yarns

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.