Textile Engineering

The quite often contact of textile goods with sharp objects, results in the puncture and in many cases the tear of the textiles. Thus, the determination of the tearing strength of textile articles occupies a very distinctive position among the various textile quality control tests. The ...

A mechanical method for reducing the spirality of single jersey tubular weft knitted fabrics is described. Initial attempts, using a false twisting device, did not prove successful. A later, successful method was developed, based on changes in yarn torque produced by a steaming and untwisting method. The new method is shown to be very effective in reducing spirality. Microscopic examination of changes in yarn structure, including characteristics of fibre migration have also been carried out.

The observation of individual fibres in a mass of fibres becomes possible with the tracer fibre technique. For the microscopic examination of ring-spun yarns containing tracer fibres, the depth of focusing is used as a reference for the fibre location inside the body of the yarns. Threedimensional configurations of the examined fibres in the yarns are generated by computer graphics. This method will assist researchers who are working in the field of yarn and fabric structural mechanics.

The effect of yarn steam setting and fabric washing on spirality has been studied and a brief description of a yarn treatment, based on the false twisting process, worked out towards the solution of this problem is given.The results indicate that a possible method for the reduction of the spirality effect should include a real reduction in the twist liveliness or torque existing in the yarns.

The formation of snarls that takes pl ace in the yarns in post-spinning processes, such as winding, warpin g, weaving and knitting, has been studied. This de fect is due to the excessive yarn twist liveli ness (torsional buckling) and causes g re at trouble to thc manufacture rs of yarns and fabric s. Biased test in g techniques are used for the measurement of this defect. A snarlin g testing apparatus PRIANIC and an unbiased testing technique have been developed and are reported. The investigati on of factors such as yarn package form, yarn twist factor, tim e elapsed between production and processing stages of yarns and yarn condi ti oning show the s ignificant role th ey play in the reduction of yarn snarliness.

The alteration in the yarn properties that possibly occurs during the detwisting process has been experimentally studied. A small reduction in yarn tenacity and hairiness and slight changes in other yarn properties have been observed. It is shown that the yarn steam setting is essential for getting the best results in spirality reduction. The avoidance of any time delay between yarn detwisting and fabric knitting contributes positively to the minimization of fabric spirality.

The effect of partially detwisting steam-set yarns on spirality is studied. It is observed that partial detwisting reduces significantly and in some cases eliminates the spirality of weft knitted fabrics produced from singles ring-spun yarns. As this technique is applied, two phenomena appear that disobey the rules concerning the relationship of yarn twist direction, twist liveliness and fabric spirality, indicating that these three factors are inter-related with the yarn torque.