Determination of core, spun yarn coverage

Core spun yarn provides a layered structure for placing fibers of different characteristics to achieve optimum performance. Although several spinning systems can, be used to produce core yarns, ring spinning is by far the dominant method adopted by the industry. Complete cover of the core by the surface fibers is difficult to achieve, and a common problem in ring spun core yarns is a periodic exposure of the core along the yarn, often referred to as the barber pole effect. We have developed a flatbed scanner-based image analysis method to determine the surface fiber coverage of core yarn. Two image analysis algorithms, one based on thresholding and the other based on Fast Fourier Transform, were used to derive different indicators of yarn coverage. Results obtained using these two methods correlated very well with each other and showed a good agreement with subjectively assessed ranking orders.