Study on the packing density of structurally modified ring spun yarn

Fibres being the structural unit of a yarn, its nature, composition and arrangement can influence structure and properties. The performance of yarn changes with arrangement of its constituent fibres. Arrangement of fibres in a yarn being system specific, different spinning system results different arrangement of fibres causing variation in product performance. A change in the arrangement of fibres in an already formed yarn can be brought about by suitable physical and/or chemical treatment. A treatment to remove a component is expected to cause changes in final arrangement of fibres in a yarn. In the present study, polyester/PVA blended yarn was modified through dissolution of the later component. The resultant change in structural arrangement on dissolution was assessed by the change in radial packing distribution of fibres. Migration index, helped in identifying the location that was influenced more in the redistribution. In the parent yarn, PVA had a preferential tendency to predominate near the core. On dissolution of PVA, creation of open space was expected and collapsing of the structure led to a possible rearrangement of fibres and reduction in diameter of yarn. Fibre denier, blend ratio and twist factor were also found to influence packing density both in parent and modified yarn. Unlike published reports, interestingly, an increase in fibre packing density was observed on dissolution of PVA. Average packing density in parent yarn was found to lie at a yarn radius between 0.07 mm to 0.09 mm while for the modified yarn it was between 0.05 mm to 0.07 mm.     

A novel method to reduce hairiness level of ring spun yarn

The quality of ring spun yarns is largely determined by its level of hairiness. The existence of hairiness inevitably affects the quality of ring spun yarns. This paper presents an innovative method on lowering the level of hairiness of ring spun yarns. This can be achieved by shooting compressed air to the yarn, through a swirl nozzle comprising a yarn duct and an airjet nozzle attached to a traditional ring spin frame. When compressed air is applied from the air-jet nozzle to the yarn duct, the swirling air flow tucks surface fibers of the ring spun yarns into its body. Four controllable variable parameters for the process, supplied pressure, nozzle position, twist factor and spindle speed, and their effects on the lowering of yarn hairiness will be clarified. Their impact on the quality of the yarn is statistically analyzed, and the optimum outcome of the combination of parameters for the process, will thus be determined.     

Studies on structural integrity of polyester-cotton friction spun yarn by cycling extension test

Yarns and fabrics are subjected to a low level of stresses or strains of repetitive nature in processing and actual use which leads to breakage, permanent deformation, bagging and loss of useful life of the product. The ability of the spun yarns and fabrics to withstand such stresses depends upon their structural integrity. A structurally rigid yarn (i.e. yarns in which fibres are tightly bound) would behave more like an elastic solid and consume more energy during deformation as the constituent fibres have to be deformed. Once the strain is released, the recovered energy will also be more. On the other hand if the structural integrity of the same yarn is poor, fibres would easily slip during deformation and would consume much less energy. The recoverable energy also will be much less. The present investigation reports on the structural integrity of friction spun yarns in terms of energy loss or decay by employing cyclic extension test. It has been observed that friction spun yarns in which the core is immediately wrapped by long and strong polyester fibre layer make the structure strongest as polyester is expected to form tight wrappings. The decay in deformation energies during extension cycling depends upon sheath structure i.e. its composition and location of constituent fibres in sheath layers. With increase in core fibre %, the decay has been found to increase. However, the decay values discriminate more between core% differences than between sheath fibre layer arrangements.     

Reducing ring spun yarn hairiness via spinning with a contact surface

In this study, spinning with a contact surface was introduced as a simple and energy-saving method to reduce spun yarn hairiness. Theoretical analysis indicated that yarn hairiness could be reduced via a sufficient long contact surface applied in other part of yarn formation zone in addition to spinning triangle. Then, a simple contact apparatus was installed on ring frame to validate the theoretical analysis. Results proved that yarn hairiness was reduced via a contact surface in the yarn formation zone. However, unevenness was deteriorated for most yarns spun with contact apparatus during the spinning, which might be due to fiber mass concentration. Most of yarns spun with contact apparatus had a lower strength than the conventional yarns. This might be because evenness deterioration to decrease yarn strength overpowered hairiness reduction to increase yarn strength for most yarns spun with a contact surface.     

纺纱方式对长绒棉高支纱性能的影响

为明确不同长绒棉纤维适纺性能及不同纺纱方式下的成纱质量,以新疆5个长绒棉品种(系)(新海35号、新海53号、新海57号、丰海8号、丰海7号)的纤维为原料,采用普通环锭纺和紧密纺2种纺纱方式,纺100S纯长绒棉纱,并对成纱性能进行测试.结果:与环锭纺相比,紧密纺大大提高了成纱的强伸性能,降低了3 mm毛羽指数,改善了条干...     

Comparison of artificial neural network and linear regression models for prediction of ring spun yarn properties. I. Prediction of yarn tensile properties

In this study artificial neural network (ANN) models have been designed to predict the ring cotton yarn properties from the fiber properties measured on HVI (high volume instrument) system and the performance of ANN models have been compared with our previous statistical models based on regression analysis. Yarn count, twist and roving properties were selected as input variables as they give significant influence on yarn properties. In experimental part, a total of 180 cotton ring spun yarns were produced using 15 different blends. The four yarn counts and three twist multipliers were chosen within the range of Ne 20–35 and α _e 3.8–4.6 respectively. After measuring yarn tenacity and breaking elongation, evaluations of data were performed by using ANN. Afterwards, sensitivity analysis results and coefficient of multiple determination (R²) values of ANN and regression models were compared. Our results show that ANN is more powerful tool than the regression models.     

Comparative study of cellulase treatment on low stress mechanical properties of cotton denim fabric made by torque-free ring spun yarn

Cellulase is useful for bio-polishing cotton fabrics which enhances their aesthetic performance instead of stonewashing process. Torque-free ring spun process is a widely used technique to produce newly low-twist and balanced torque yarns with soft hand. In this paper, denim fabrics woven with torque-free ring spun yarn and conventional ring spun yarn respectively were treated with cellulase under the same condition and their fabric handle, expressed as low stress mechanical properties, such as tensile strength, bending, shearing, compression and surface performance were investigated by Kawabata Evaluation System for Fabric (KES-F). After cellulase treatment, both denim fabrics revealed better flexibility, elasticity recovery, raised shearing stiffness, fluffier and improved smoothness. While torque-free ring spun yarn made denim fabric showed a better fabric handle than conventional ring spun yarn made denim fabric.     

Effects of spinning processes on HVI fiber characteristics and spun yarn properties

The effects of opening, carding, and repeated drawings on single fiber and bundle cotton characteristics were studied by employing Mantis®, AFIS® and HVI Testers. Some of the significant changes in single fiber properties were found to be due to process parameters as well as the changes in the fiber crimps, parallelness of fibers within HVI beards, and the actual changes in the tensile properties of the fibers. The study showed that the HVI test data taken just prior to spinning had the highest correlation with the yarn tensile properties. Based on the study results, we point out the potential of HVI for future quality and process control in spinning by recommending a set of expanded HVI output that is more scientific and comprehensive for the future control needs.     

Prediction of rotor spun yarn strength using support vector machines method

A new method for rotor spun yarn prediction from fiber properties based on the theory of support vector machines (SVM) was introduced. The SVM represents a new approach to supervised pattern classification and has been successfully applied to a wide range of pattern recognition problems. In this study, high volume instrument (HVI) and advanced fiber information system (Uster AFIS) fiber test results consisting of different fiber properties are used to predict the rotor spun yarn strength. The results obtained through this study indicated that the SVM method would become a powerful tool for predicting rotor spun yarn strength. The relative importance of each fiber property on the rotor spun yarn strength is also expected. The study shows also that the combination of SVM parameters and optimal search method chosen in the model development played an important role in better performance of the model. The predictive performances are estimated and compared to those provided by ANFIS model.     

Investigating the effect of yarn count and twist factor on the packing density and wicking height of lyocell ring-spun yarns

The moisture transport expressed with wicking is one of the most important aspects in clothing science and strongly effects on the quality of clothes. Wicking is a spontaneous transport of liquid driven into a porous system by capillary forces. Furthermore, the packing density has a direct relation with the yarn structure. At the present work, the effects of yarn count and twist factor on the wicking height and packing density of lyocell ring-spun yarns was investigated. Achieving the objectives of this research, an image processing method was developed to determine the packing density of samples. Experimental results were also used to develop a regression model to predict the wicking height based on the packing density, yarn count, twist factor and rising time. The results demonstrated that the correlation coefficient between the predicted and measured wicking height was 0.98 indicating the capability of the presented model to predict the wicking height of lyocell ring-spun yarns.     

Effect of repeated winding on carded ring cotton yarn properties

In this study, ten carded ring spun cotton yarns were subjected to windings. Yarn hairiness, fineness, unevenness and tensile properties were then examined. Results showed that the majority of the increased yarn hairiness occurred at the beginning cycles of windings. Weight loss occurred for most yarns after repeated windings. Tensile properties deteriorated for nearly all the yarn samples after repeated windings. On the contrary, yarn unevenness was improved for most yarns after corresponding windings. To explain the better evenness of yarn after repeated windings, unevenness of yarn was divided into two parts, namely stem unevenness and surface hairiness unevenness; yarn imperfections were subdivided into two categories: the imperfections of yarn stem and the imperfections caused by yarn hairs. Specifically, a balanced opinion was given to discuss the gains and losses in quality and cost due to repeated windings.     

Modelling of ring yarn unevenness by soft computing approach

This paper demonstrates the application of two soft computing approaches namely artificial neural network (ANN) and neural-fuzzy system to forecast the unevenness of ring spun yarns. The cotton fiber properties measured by advanced fiber information system (AFIS) and yarn count have been used as inputs. The prediction accuracy of the ANN and neural-fuzzy models was compared with that of linear regression model. It was found that the prediction performance was very good for all the three models although ANN and neural-fuzzy models seem to have some edge over the linear regression model. The linguistic rules developed by the neural-fuzzy system unearth the role of input variables on the yarn unevenness.     

An experimental investigation of yarn tension in simulated ring spinning

Yarn tension is a key factor that affects the efficiency of a ring spinning system. In this paper, a specially constructed rig, which can rotate a yarn at a high speed without inserting any real twist into the yarn, was used to simulate a ring spinning process. Yarn tension was measured at the guide-eye during the simulated spinning of different yarns at various balloon heights and with varying yarn length in the balloon. The effect of balloon shape, yarn hairiness and thickness, and yarn rotating speed, on the measured yarn tension, was examined. The results indicate that the collapse of balloon shape from single loop to double loop, or from double loop to triple etc, lead to sudden reduction in yarn tension. Under otherwise identical conditions, a longer length of yarn in the balloon gives a lower yarn tension at the guide-eye. In addition, thicker yarns and/or more hairy yarns generate a higher tension in the yarn, due to the increased air drag acting on the thicker or more hairy yarns.     

Prediction of rotor spun yarn strength from cotton fiber properties using adaptive neuro-fuzzy inference system method

In this study, we present the application of a hybrid neuro-fuzzy system for the prediction of cotton rotor spun yarn strength from cotton fiber properties. The proposed system possesses the advantages of both artificial neural networks and fuzzy logic, and is thus more intelligent. HVI (high volume instrument) and Uster AFIS (advanced fiber information system) fiber test results are used to train the neuro-fuzzy inference system. We also study the degree of impact of each fiber property on the rotor spun yarn strength. Fiber strength, upper half mean length, length uniformity and yarn count have a positive impact whereas micronaire, yellowness and short fiber content have a negative impact on rotor spun yarn strength.     

Processing parameters optimization of draw frame for rotor spun yarn strength using gene expression programming (GEP)

Breaking strength is one of the most important mechanical property of a yarn as it is the main parameter for quality control. This property depends on many different factors namely, raw material factors, process variables and machine parameters. Since, there is a high degree of interaction between yarn properties and influencing factors therefore, optimal processing conditions can not be determined easily. This article proposes prediction approach for the determination of the breaking strength of the yarn using gene expression programming (GEP) and optimization technique using MATLAB software. A nonlinear mathematical function was derived on the basis of draw frame variables that were distance between back and middle rolls, delivery speed and break draft by GEP. Afterward, optimal conditions were found in such a way that breaking strength to be maximized. Study showed that, optimal processing parameters including distance between back and middle rolls, break draft and delivery speed were respectively, 10.70 mm, 1.90 and 541.51 m/min (687.95 or 721.32 based on the optimization procedure).     

Studies on reduction of yarn hairiness by nozzles in ring spinning and winding by airflow simulation

Reduction of yarn hairiness by nozzles in ring spinning and winding is a new approach. Simulation of the airflow pattern inside the nozzles provides useful information about actual mechanism of hairiness reduction. The swirling air current inside the nozzles is capable of wrapping the protruding hairs around the yarn body, thereby reducing yarn hairiness. Since production rate of winding is very high and the process itself increases yarn hairiness any method to reduce the hairiness of yarns at this stage is a novel approach. A CFD (computational fluid dynamics) model has been developed to simulate the airflow pattern inside the nozzles using Fluent 6.1 software. In this study, both S- and Z-type nozzles having an axial angle of 50° and diameter of 2.2 mm were used for simulation studies. To create a swirling effect, four air holes of 0.4 mm diameter are made tangential to the inner walls of the nozzles. S- and Z-twisted yarns of 30 tex were spun with and without nozzles and were tested for hairiness, tensile and evenness properties. The total number of hairs equal to or exceeding 3 mm (i.e. the S3 values) for yarn spun with nozzle is nearly 49–51 % less than that of ring yarns in case of nozzle-ring spinning, and 15 % less in case of nozzle-winding, while both the yarn types show little difference in evenness and tensile properties. Upward airflow gives best results in terms of hairiness reduction for nozzle-ring and nozzle wound yarns compared to ring yarns. Yarn passing through the centre of the nozzle shows maximum reduction in S3 values.     

Effect of fiber friction, yarn twist, and splicing air pressure on yarn splicing performance

The impact of fiber friction, yarn twist, and splicing air pressure on mechanical and structural properties of spliced portion have been reported in the present paper. The mechanical properties include the tensile and bending related properties and, in the structural properties, the diameter and packing density of the splices are studied. A three variable three level factorial design approach proposed by Box and Behnken has been used to design the experiment. The results indicate that there is a strong correlation between retained spliced strength (RSS) and retained splice elongation (RSE) with all the experimental variables. It has been observed that RSS increases with the increase in splice air pressure and after certain level it drops, whereas it consistently increases with the increase in yarn twist. The RSE increases with the increase in both fiber friction and yarn twist. It has also been observed that the yarn twist and splicing air pressure have significant influence on splice diameter, percent increase in diameter and retained packing coefficient, but the fiber friction has negligible influence on these parameters. Yarn twist and splicing air pressure has a strong correlation with splice flexural rigidity, where as poor correlation with retained flexural rigidity.     

The effect of physical ageing on torque in worsted spun yarns

The intrinsic torque of freshly spun wool yarns is affected by ageing of wool roving prior to spinning as well as the storage time of the yarn after spinning. The effect of physical ageing of roving on yarn torque properties has not been observed before and this study shows that the yarn intrinsic torque increases with ageing of the roving and decreases or relaxes with the yarn storage time. The dependency of the intrinsic torque on the roving ageing time and the yarn storage time after spinning show a simple double-logarithmic shift factor of 0.42 compared with the value of 1 found generally for amorphous polymeric materials. The self-plying twist of the yarns used in this study shows a close link to the intrinsic torque and both are affected by the history of the roving prior to spinning. Significant reductions in the self-plying twist were obtained when deaged rovings were used in spinning. When self-plying twist is used as a predictor of fabric spirality the roving and yarn history needs to be considered. This study shows that low intrinsic torque yarns can be produced by deageing of the roving prior to spinning.     

Effect of braid structure on yarn cross-sectional shape

The effect of braid construction parameters on yarn cross-sectional shape is presented in this paper. The location of the yarn within the braid unit cell is quantified by a compaction factor. A range of braided fabrics were produced and optically measured for actual yarn cross-sectional shape. A comparison of the theoretical and experimental values shows good correlation. Design curves can be produced with the developed model to allow selection of appropriate braid process parameter to create yarns with desired cross-sectional geometries.