Factors Affecting Yarn Appearance and Imperfections In the Mills

Abstract

<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:arial;mso-ansi-language:en-us;mso-fareast-language:="" en-us;mso-bidi-language:ar-sa"="">Fabric quality in the mills is often marred by high incidence of neps, clusters and specks in the yarn. Studies in a number of mills have shown that yarn spun in pilot plant from mill mixing is relatively free from such defects and is on an average 1 ASTM grade better in appearance than the mill yarn. The causes for poorer yarn appearance in mill spinning have been investigated in detail in this study. Harsh blowroom treatment was found to be responsible for the higher nep incidence in the yarn in many mills. By choosing the right type of metallic wire for cylinder and licker-in, by employing a proper schedule for grinding and by eliminating defective flat seating on the flexible bend in carding, significant improvements in appearance and imperfection level could be obtained in some mills. The scope for improvement of comber performance to get better yarn quality was found in a majority of the mills. Poor half lap condition and improper setting of top comb and disturbances in settings were found to be the causes for the higher nep level in mill combing. Curling of fibres, holes in the web and defective web appearance were commonly encountered in the mills' combers; these were caused by poor nipper grip, defective top detaching roller weighting and sticking tendency of the web to the top detaching roller. Elimination of the web defects helped to bring down the imperfection level in the yarn significantly.</span>