INVESTIGATION INTO THE PERIODICITY OF MASS VARIATION OF YARN AND ITS EFFECT ON FABRIC APPEARANCE

Abstract

Abstract The appearance of a fabric can be greatly affected if the yarn has a sufficiently pronounced periodic component. The severity of the periodic fault can only be estimated if its intensity is quantified. Even though a spectrogram is more reliable than other tools at determining periodicity, it gives only the resolved mass variation, which may not be present in the final yarn when different faults are superimposed. The relative index of irregularity of yarn is considered as a measure of the intensity of a periodic fault of a spun yarn. By correlating the above index with the relative unlevelness indices of finished fabrics knitted from yarn samples produced at different levels of roller eccentricity, we have established the threshold value of the relative index of irregularity of yarn which produces worse appearance values in the fabric.