Influence of some knitting and finishing parameters on the snag resistance of polyethylene terephthalate (PET) knit fabric

To assess the effects of fabric take-up, yarn tension, feeder position, and yarn feeder material on the occurrence of snagging, fabrics produced with two different finishing processes, were subjected to longitudinal or transversal 100, 300, and 600 revolutions, and the degree of snagging was measured and compared afterwards with gray fabric. Our results showed that, during the knitting process, the use of ceramic yarn feeders resulted in significantly fewer snags compared with metal yarn feeders. The gray fabric, having no finishing, was fragile and easily snagged, whereas the fabric treated by a finishing process – either drying in relaxed condition (Treatment A) or under stress conditions (Treatment B) – was more resistant to snagging. Moreover, the snagging property of the gray fabric tended to increase with increasing longitudinal or transversal 100, 300, or 600 revolutions. Slight increases in snagging were also present in fabrics having Treatment A or Treatment B at the same revolutions, but the differences were not statistically important ( P > 0.05). Frequency of snags was higher when revolutions were transversal rather than on longitudinal direction. Yarn tension and feeder position had no effect on snagging degree, while fabric take-up had limited effect. For acquiring a fabric resistant to snagging, the gray fabric produced with ceramic yarn guiders during the knitting process should be subjected to drying under relaxed condition. We also suggest that quality control tests be carried out taking the results of our study into consideration.

Experimental simulation of bending damage of silicon nitride yarn during 3D orthogonal fabric forming process

The aim of this study executed on Silicon Nitride (Si3N4) yarn is to examine some bending damage behaviors and fracture mechanisms that occur during the 3D orthogonal fabric forming process. A three point bending experiment device has been developed in order to simulate the Z-binder yarn bending condition. The effects of weft density, fabric thickness, and yarn tension have been studied. The Weibull analysis of the tensile strength show that the bending damage increases with the increase of weft density, fabric thickness, and yarn tension. The resulting bending damage causes a reduction in yarn strength of between 2.5 and 17.2% depending on the bending parameters of yarn. The growth of the fibrillation area also reflects similar trends with tensile strength loss rate. The fibrillation length produced by the yarns is mostly distributed within the range of 0.3 to 0.9 mm. A comparison of the calculation result to experimental data shows the bending fracture probability of filaments inside yarn are less than that of monofilament. The tensile and bending fracture of Si3N4 filaments exhibit typical brittle fracture characteristics.

Yarn tension control technique for improving polyester soft winding process

The textile industry has a great role in the improvement of any country’s economy. Moreover, the ready-made garments need different coloured high yarn quality, so yarn should be rewinded on plastic cones for dyeing. However, manufacturers are facing the problem of tension variation during soft winding process that mainly affects the yarn quality. Consequently, to overcome the tension variation drawbacks, the attainment of constant optimal tension values is required in order to: (1) Increase the winding speed while maintaining the yarn quality, (2) Improve the dyeing quality, and (3) Reduce the water consumption during the dyeing process. In this paper, a proposed yarn tension control technique is introduced to upgrade the soft winding machine, thus maintain the yarn quality and improve the manufacturing capacity. The proposed technique has been tested on Polyester yarn samples classified as; fine, medium and coarse yarn counts, to cover most yarn sizes used in the industry. Arduino Mega 2560 controller is utilized to implement the proposed tension control. The results are compared to the conventional system to advocate the effectiveness and capability of the proposed technique in overcoming the trade-off between tension control and machine speed that occurs in conventional system using variable tension levels.

Construction and system realization of the yarn tension model of fully fashioned flat knitting fabric

In recent years, fully fashioned flat knitting fabrics have been extensively studied owing to their superior formability, rich application range and advanced knitting technology. However, the yarn tension fluctuations during the knitting process are difficult to control. The yarn tension in the knitting process is affected by many factors, such as the carriage running speed, structure, yarn properties, clothing parameters, and so on. In this work, a tension model of the yarn was established to explore the regularity of yarn tension variation, which was caused by the running speed and direction of the carriage when producing fully fashioned fabrics. Then, a tension compensation device was set up to reduce tension fluctuations to improve the quality of fully fashioned fabrics. Results showed that the tension fluctuation in the dynamic change of the tension was reduced to a certain extent by adding the tension compensation device. Meanwhile, the average value and fluctuating standard deviation of the yarn tension between the forward and backward processes were significantly reduced during a cycle of the knitting process. This indicates that controlling the tension fluctuation in the knitting process will effectively improve the surface evenness of the fully fashioned flat knitting fabric.