Analysis of spinning process using the Taguchi method. Part I: Effect of spinning process variables on fibre orientation and tenacities of sliver and roving

Abstract

The effect of drafts at different stages of spinning process on fibre orientation and tenacities of sliver and roving has been studied by using Taguchi method and analysis of variance. Among all the fibre orientation parameters analysed the ‘coefficient of relative fibre parallelization (K _rp)’ influenced the maximum with change in process variables. Further, the equation used for calculation of K _rp was critically analyzed and modified for a better explanation of fibre orientation. The fibre orientation in sliver and roving was also studied in terms of a new index of measurement of fibre straightness along the length. Increase in lap hank and card draft increases proportion of curved fibre ends (ρ) and decreases K _rpm in card and breaker sliver. However, the improvement in K _rpm is seen to be higher in finisher sliver and roving produced by finer lap hank and higher card draft in subsequent processes. Increase in lap hank, card draft and draft/doublings decrease the FSI in slivers. The lower speed frame draft tends to decrease fibre straightening index (FSI) of roving. Further, a combination of K _rpm, ρ and FSI values is seen to decide the strength of slivers.     

The Detection of Irregularity Sources by Variance–Length Curves

Abstract

The migration in ring yarn (type I and type II), rotor yarn and air-jet yarn was studied in terms of three parameters - mean fibre position (MFP), mean migration intensity (MMI) and root mean square deviation (RMSD) - using classical tracer fibre technique. The effect of various process variables on migration parameters was analysed using the Taguchi method, analysis of variance and a regression model. The trends of migration parameters in ring yarn-type I are opposite to those of ring yarn-type II. The ring yarn has the highest MFP and the lowest MMI. The rotor yarn has the lowest MFP and RMSD. The air-jet yarn has the highest MMI and RMSD. Increase in card draft increases the MMI and RMSDof rotor yarn and decreases the MMI of air-jet yarn.However, it tends to increase the RMSD of ring yarn-type II, rotor yarn and air-jet yarn. A high draft/doublings at draw frame increases MFP in ring yarn-type II, rotor yarn and air-jet yarn. A decrease in ring frame/air-jet draft or an increase in speed frame draft decreases MFP in these yarns. All the migration parameters follow almost the same trends with change in process variables in rotor yarns.     

Influence of fibre strength and yarn structural characteristics on tensile failure of blended spun yarns: a prediction model

The study reports on the static failure behaviour of P/V blended ring, rotor and air-jet spun yarns explained on the basis of fibre failure coefficient. Fibre failure coefficient is an index introduced to represent fibre break and slip in combination occurring during tensile failure. Fibre break/slip during tensile failure is found dependent on fibre strength, fibre cohesiveness and internal structural developments in yarns. Tensile failure behaviour of ring, rotor and air-jet yarns found to be different owing to their difference in fibre consolidation mechanism. The contribution of individual components towards fibre failure coefficient varies with the spinning technology. An attempt has been made to develop mathematical models to explain the spun yarn failure behaviour under static condition. The developed mathematical models have incorporated the fibre property (fibre strength) and few structural characteristics of yarns which are strategically selected to justify the essence of models to enhance the prediction capability. Individual models are developed for ring, rotor and air-jet yarns owing to their structural changes caused by their inherent fibre consolidation mechanism. The developed mathematical models are free from assumptions and based on pure applied mathematics and have very high potential for prediction of spun yarn failure behaviour.     

Evaluation of the dual-feed rotor spinning unit based on airflow dynamics and blended yarn properties

In fiber processing on a rotor spinning machine, the fiber orientation gained in pre-processing stages like carding and drawing is mainly lost as the fibers enter the rotor interior for further processing. To improve fiber orientation and facilitate fiber blending, a new dual-feed rotor spinning unit is proposed. We present a comprehensive numerical evaluation of the airflow dynamics in the original and the proposed rotor spinning unit based on finite volume methods. The velocity profiles, pressure distribution, vortices, streamlines, and drag force in the two prototypes are evaluated. Results reveal that the velocity magnitude and pressure in the dual-feed unit adopt an even pattern and the total drag force reduction of up to 60–80% is achieved. Comparison of the yarn quality properties of the two systems showed that the dual-feed spun yarns possess superior quality compared to the conventional yarns.     

Effect of polyester and elastane linear density on the physical and mechanical properties of dual-core-spun cotton yarns

ABSTRACT

The use of single-core elastic spun cotton yarns is well established in textiles and denim industry but interest in the use of dual-core-spun yarns has started to grow only recently. The aim of this study was to investigate the effect of polyester and elastane linear density on the physical and mechanical properties of dual-core-spun cotton yarns. Yarn samples were prepared on industrial-scale spinning machines using cotton as the sheath fibers and two different linear densities of polyester and three different linear densities of elastane filaments in the core. Statistical analysis of the results revealed that yarn tenacity, elongation, uniformity, and hairiness are significantly affected by the linear densities of both the polyester and elastane filaments in the core, with statistically significant interaction between them. Yarn imperfections (IPI), however, are affected mainly by the polyester denier, while the elastane linear density did not show statistically significant effect on the IPI. Regression equations for different yarn properties were also developed which showed fairly high values of coefficient of determination (R-sq).     

Effect of elastane linear density and draft ratio on the physical and mechanical properties of core-spun cotton yarns

The aim of this study was to investigate the effect of elastane linear density and draft ratio on the physical and mechanical properties of core-spun yarns. Twenty yarn samples were prepared on industrial scale in a spinning mill with two different yarn linear densities, each with different two elastane deniers and five draft ratios. It was found that core-spun yarn’s tenacity, elongation and hairiness are affected not only by the overall yarn linear density but also by the elastane linear density and the draft ratio. However, the effect of elastane linear density and draft ratio was not found to be statistically significant on the yarn mass variations and total imperfections, which are only affected by the overall yarn liner density. A statistically significant interaction for yarn elongation at break was found between the yarn liner density and the elastane linear density concluding that elastane linear density used in the core must be compatible with the overall yarn liner density for attaining the best yarn elongation.     

Analysis of the effect of fiber cross section and different bonding methods on sound absorption performance of PET fiber based nonwovens using Taguchi method

Abstract

In this study, sound absorption coefficients (SACs) of needle-punched and thermal-bonded nonwovens produced from polyester (PET) fibers with various cross sections, i.e., hollow, round and hexaflower, blended with a low melt PET, was reported. The acoustic performance of a hexaflower PET fiber was studied for the first time. Fibers were carded and then one set of samples was bonded by needle punching while the other set was air-through thermal bonded. A third set of samples was needled at various punch densities. Design of experiments was planned according to Taguchi method. Relationship between production parameters and SAC was analyzed using Minitab software. The most important independent variables affecting the sound absorption were areal density and web bonding method. The sample produced according to optimum production levels reached to a SAC value of 0.57 at 2000?Hz which could be a suitable choice for acoustic applications in the automotive industry.     

磁悬浮轴承用飞轮电池转子和基体的模态分析

为了使磁悬浮转子在高速旋转时不会发生共振,运用有限元分析软件建立了转子和基体的有限元模型,采用Block Lanczos法计算了其前10阶固有频率和振型。研究结果表明,转子和基体的固有频率相差很大,基体受力变形只有微米级,不会对转子的正常工作产生影响,该有限元模型为柔性转子的设计和优化提供参考价值。     

Alternatives to conventional thermal treatments in fruit-juice processing. Part 2: Effect on composition,phytochemical content,and physicochemical,rheological, and organoleptic properties of fruit juices

Traditional thermal techniques may cause losses in nutritional quality and phytochemical contents, and also in physicochemical, rheological, and organoleptic properties of processed fruit juices. This paper provides an overview of the effect on these qualities by the use of alternatives to traditional thermal treatments in fruit-juice processing, for three key operations in fruit-juice production such as microbial inactivation, enzyme inactivation, and juice-yield improvement. These alternatives are UV light, high-intensity light pulses, γ-irradiation, pulsed electric fields, radiofrequency electric fields, Ohmic heating, microwave heating, ultrasound, high hydrostatic pressure, supercritical carbon dioxide, ozonation, and flash-vacuum expansion. Although alternatives to heat treatments seem to be less detrimental than the thermal treatment, there are many parameters and conditions that influence the output, as well as the nature of the juice itself, hampering comparisons between different studies. Additionally, future research should focus on understanding the mechanisms underlying the changes in the overall quality of fruit juices, and also on scaled-up processes, process design, and optimization that need to be deal with in detail to maximize their potential as alternative nonthermal technologies in fruit-juice processing while maintaining fruit-juice attributes to the maximum.     

Effect of the production method on the properties of RS3/RS4 type resistant starch. Part 1: Properties of retrograded starch (RS3) produced under various conditions and its susceptibility to acetylation

The objective of this study was to establish the effect of the concentration of a starch paste subjected to freezing on the properties of the produced retrograded starch, and to determine its susceptibility to acetylation with acetic acid anhydride. A starch paste (1, 4, 10, 18 or 30g/100g) was produced from native potato starch that was frozen, defrosted and dried. Al preparations of retrograded starch had the same chemical structure determined with the technique of nuclear magnetic resonance (NMR) and diversified physical form visible on photos taken with an electron microscope (SEM). An increase in the concentration of paste, used to produce the preparations, resulted in decreased: amylose content (from 25.0 to 20.4/100g), solubility in water (from 41.1 to 20.1/100g), swelling power (from 45.0 to 19.3/g), and susceptibility of the preparations to the action of amyloglucosidase (from 95.4 to 83.6/100g). The heat of phase transition of solubilisation determined with differential scanning calorimetry (DSC) ranged from 3.8 to 7.1J/g, and the initial temperature of transition was increasing from 43.4 to 49.7°C along with an increasing concentration of the paste subjected to retrogradation. The 1-10/100g concentration of the paste used to produce preparations was observed to increase, whereas that between 10 and 30/100g to decrease the susceptibility to acetylation and viscosity of the prepared pastes, determined both with a Brabender viscograph and a Haake oscillating-rotational viscosimeter.     

Effect of the addition of whole‐grain wheat flour and of extrusion process parameters on dietary fibre content,starch transformation and mechanical properties of a ready‐to‐eat breakfast cereal

This study evaluates the effect of the incorporation of whole‐grain wheat flour (WGWF) and of extrusion process parameters on the nutritional and technological quality of breakfast cereals. The corn flour‐based breakfast cereals were elaborated in a twin‐screw extruder following a rotatable central composite design with varied WGWF (0–100%), feed moisture (14–24%) and zones 3 and 4 barrel temperature (76–143 °C). Dietary fibre and resistant starch were significantly increased with WGWF addition. Total and digestible starch showed a decrease when WGWF increased. The RVA parameters were significantly affected by all the extrusion conditions and WGWF content. The cell structure of the extrudates was dependent of WGWF and moisture.