End Breakage Research Articles

Ultrastructural aspects of fibre development during the stone groundwood process: New insights into derived pulp properties

Abstract A study was performed on stone groundwood (SGW) pulps produced on a pilot scale. The behaviour of selected juvenile and mature Norway spruce wood samples was investigated. As revealed by standard tests, sheets formed from juvenile wood showed improved light scattering properties, improved tear and tensile strength, and higher sheet density compared to those formed from mature wood. Scanning electron microscopy indicated that the differences are likely related to the manner of fibre processing and development at the ultrastructural level. Mature wood fibres showed greater fibre end breakage, a smaller long-fibre fraction, enhanced S1 fibrillation and frequently open fibres. In contrast, juvenile fibres had a 14% higher long-fibre fraction and showed typical S2 fibrillation. Fibre development of juvenile wood showed fibrillation features similar to those previously reported for thermomechanical pulp fibres. In both cases, the structural hierarchy of the wood fibre cell wall and the microfibril angle of S2 and S1 layers govern cell-wall splitting and fibrillation progression. The superior quality of the fibre furnish prepared from juvenile fibres compared to mature fibres with SGW pulping may offer an alternative process for more effective utilisation of raw materials such as top logs rich in juvenile wood.

OPTIMIZING RING SPINNING VARIABLES AND A PROPOSED PROCEDURE TO DETERMINE THE EGYPTIAN COTTON SPINNING POTENTIAL

In this study, many approaches were examined such as spindle defects and yarn bobbin position along with successively varying spindle speed to select the optimum processing parameters for standard testing of the Egyptian cotton, and hence suggesting a spinning procedure for the CRI 96-spindle-hour spinning test. Giza 80 was used to test the spindle error and yarn bobbin position also, to study the varying spindle speed, while, Giza 80 as well as Giza 86 and Giza 70 were used to reveal the spinning limit technique. The coefficient of variation in lea count strength product (introduced between the spindles of the ring frame) was considerable, the variance was very small (1.01 %) in extreme cases and could be neglected. The lea count strength product at different positions on the bobbin spun on the ring frame between the pigtail to full bobbin was insignificant. The increase in spindle speed from 1000 to 17500 rpm did not affect single yarn strength, yarn evenness and yarn hairiness. The total imperfections are minimum at 10000 rpm of spindle, and beyond this speed the imperfections increase gradually with the increase in spindle speed. The proposed procedure of accelerated spinning technique appears promising in indicating the relative level of end breakage and optimum yarn quality parameters for different cotton varieties. A series of 96- spindle-hour spinning tests proved to be reliable in exploring practical spinning limits of any cotton to find out the finest count for a particular cotton taking in consideration ends-down and yarn quality parameters

Studies on the Reduction of Coefficient of Variation: A Case Study

In a spinning mill, yarn is the final product. Linear density expressed in terms of count is one of the important characteristics of yarn. Because variability of textile strands increases as the linear density increases, the variability in the count is often measured in terms of coefficient of variation (CV)%. The yarn with a high CV% of count leads to a higher end breakage rate during the spinning and subsequent weaving/knitting operations, and consequently, results in lesser productivity and poorer appearance quality of the woven/knitted fabric. When this woven/knitted fabric is dyed, uneven shades are generated. Because the production of yarn involves processing of raw cotton in multimachines at multistages, possible sources that lead to a high CV% of count are many. Enrick's (1960) analysis procedure, which is based on the modification of the range method for analysis of variance, is used conventionally for detecting the stages where excessive “between-machine” differences are present. When the CV% of count is inflated due to the generation of systematic variation in any machine or introduction of high variability by any machine, this inflation remains undetected when using Enrick's procedure. The case study presented here demonstrates that a step-by-step analysis of linear densities of different stage-outputs starting from yarn to card sliver, using appropriate nested design models along with Duncan's multiple range test, is very useful in detecting all possible sources of a high CV% of count of yarn.

End Breaks in the Spinning and Weaving of Weavable Singles Yarns

An end break will occur in spinning when the tension in the balloon exceeds the strength at the weakest point in the yarn, which is at the point of twist insertion and before the fibers are fully twisted together. Other than gross faults such as slubs, the cause of an end break is generally a very thin place, the incidence of which can be estimated from the mean linear density of the yarn and its variance. A good correlation was found between the end breakage rate and the irregularity (CV%) of the yarn, which appears to be independent of yarn count. The tenacity of the yarn at a break was estimated to be only about 1.85 g/tex. For wool yarns which are woven in the warp as singles, end breaks in spinning effectively remove those thin places which are likely to break in warp ends during weaving. It is recommended that such yarns be spun at high speed to remove those short, very thin places which might not be detected in clearing, but which may fail in weaving.

End Breaks in the Spinning and Weaving of Weavable Singles Yarns

The eight weavable singles yarns studied in Part 1 of this paper were all woven plain weave and the end breaks identified by cause and recorded. End breaks were found to be due to failed splices, abrasion failure and thin places. The incidence of thin-place breaks was found to increase with increasing irregularity (CV%) of the yarn, and as the linear density of the yarn decreased. It is primarily the thin-place end breakage rate which determines the yarn count limit for acceptable weavability, and this is shown to depend on the evenness of the yarn. It is shown how to predict the thin-place end breakage rate from the yarn, fabric and loom parameters.

Finishing Oil Based on Propylene Oligomers

Finishing oil based on propylene oligomers decreases fibre end breakage and the amount of wastes, washes out well, and does not negatively affect dyeing. It is recommended for double-twisting machines in the textile industry.

END BREAKAGE IN ROTOR SPINNING: EFFECT OF DIFFERENT VARIABLES ON COTTON YARN END BREAKAGE

Abstract The end breakage in rotor spinning not only reduces the running efficiency of the process, but also deteriorates the quality of the yarn in terms of presence of piecing slubs. A new system has been proposed to classify the end breaks in rotor spinning broadly into seven groups, depending on the configuration of broken ends. By examining the broken end, the probable causes of breakage can be predicted and necessary preventive action can be taken. The rate of end breakage and the proportion of different types of breakages vary with different process variables like yarn count, rotor speed, opening roller speed and residual trash content in draw frame sliver.

THE MECHANISM OF END BREAKAGE IN RING SPINNING: A STATISTICAL MODEL TO PREDICT THE END BREAK IN RING SPINNING

Abstract The mechanism of end breakage in ring spinning is a complex phenomenon, and is entirely different from the yarn failure mechanism during a tensile test. In this paper a possible mechanism of end breakage is reported. A statistical model is developed for predicting the likely end breakage rate in ring spinning. The important factors in governing end breaks are the mean yarn strength, yarn strength variation, mean value of the peak spinning tensions and the variation of yarn mass irregularity. Some practical aspects have also been discussed to tackle the problem of when the breakage rate suddenly increases.

The Effect of Cotton Yarn Properties on Yarn End Breakage

In this work the effect of cotton yarn properties on yarn end breakage was investigated. The yarn nominal linear densities were 20, 25 and 36 tex and each of them, had three levels of twists. Following yarn properties were investigated: linear density, twists, tensile strength, elongation at break and irregularity. Standard methods were applied to determine these yarn properties and hronometric method for yarn end breakage was used. It was only the yarn linear density, among all yarn properties, that showed significant correlation with yarn end breakage (-0,75 to -0,96). It was shown that about 80% of all yarn end breakage are occurred in places with fineness lower than average cross section of the yarn that point out that the thin places of the yarn are inclined to breaking. Also, the mutuality effect of geometrical characteristics and physical-mechanical properties of the yarn on end breakage was investigated.

Mechanism of End Breakage due to Knots in Weft Knitting Zone

The mechanism of the end breakage due to knots (a weaver's knot and a fisherman's knot using a combed cotton yarn c30s/1 cotton count) in the plain-weft knitting zone is investigated in detail, using a high speed video camera.The results obtained are as follows: (1) It clarifies that the end breakage due to knots in the plain-weft knitting zone occurs in the following three steps:1) jam of knots in the space between a needle-hook and -latch and an old loop, or in the space between a needle-head and a verge, 2) increase in the yarn tension, 3) end breakage due to knots. (2) The end breakage due to an air-splice in the plain-weft knitting zone hardly occurs under every knitting condition. (3) The rate of jammed knots, the end breakage rate for jammed knots and that for knots increase with the increase of the depth of stitch draw, the input tension and the take-down weight for any knot. (4) The rate of jammed knots, the end breakage rate for jammed knots and that for knots due to a fisherman's knot are always more than those due to a weaver's knot under every knitting condition.

Mechanism of End Breakage due to Knots in Weft Knitting Zone

Mechanism of End Breakage due to Knots in Weft Knitting Zone

平編編成域での結び目による糸切れ発生機構

The mechanism of the end breakage due to knots (a weaver's knot and a fisherman's knot using a combed cotton yarn c30s/1 cotton count) in the plain-weft knitting zone is investigated in detail, using a high speed video camera.The results obtained are as follows: (1) It clarifies that the end breakage due to knots in the plain-weft knitting zone occurs in the following three steps:1) jam of knots in the space between a needle-hook and -latch and an old loop, or in the space between a needle-head and a verge, 2) increase in the yarn tension, 3) end breakage due to knots. (2) The end breakage due to an air-splice in the plain-weft knitting zone hardly occurs under every knitting condition. (3) The rate of jammed knots, the end breakage rate for jammed knots and that for knots increase with the increase of the depth of stitch draw, the input tension and the take-down weight for any knot. (4) The rate of jammed knots, the end breakage rate for jammed knots and that for knots due to a fisherman's knot are always more than those due to a weaver's knot under every knitting condition.

Predicting End Breakage Rates in Worsted Spinning

Existing models for predicting end breakage rates in spinning give unrealistic values when considering the effects of changes in count or speed on the worsted ring frame. A new approach to predicting end breaks gives results that are closer to experience values. The most important factor in determining end breaks is yarn strength variation, followed by mean yarn strength and spinning tension.

Predicting End Breakage Rates in Worsted Spinning

Successful forecasting of likely end breakage rates in spinning is governed by the availability of a reliable predictive model together with appropriate experimental data on yam strength and tension for inclusion in the model. Techniques for assessing dynamic yam strength and yam tension during ring spinning are described and the effects of various processing parameters on the values obtained are reported.

Comparison of End Breakage Rate due to Splices and Knots in Plain-Weft Knitting Zone

The effect of some factors on the end breakage rate in the plain-weft knitting zone due to three kinds of yarn joints (an air-splice, a weaver's knot and a fisherman's knot) is investigated experimentally, using a combed cotton yarn c 30s/1. End breakage in the plain-weft knitting zone due to an air-splice hardly occurs under any knitting condition. Therefore, the air-splice is a very useful yarn joint in weft knitting. The knitting defect due to a weaver's knot or a fisherman's knot is almost always caused by end breakage in the plain-weft knitting zone. This end breakage occurs near the knot on the take-down side. The end breakage rate in the plain-weft knitting zone due to a weaver's knot or a fisherman's knot increases with the increase in the depth of stitch draw, the machine gauge, the input tension, and the take-down weight. Under every knitting condition, the end breakage rate due to a fisherman's knot is more than that due to a weaver's knot.

Factors Affecting Defects in 1×1 Rib Knitted Fabrics due to Weaver's Knots of Spun Yarns

The effect of some factors on defects in 1×1 rib knitted fabrics due to weaver's knots is investigated experimentally, using a combed cotton yarn and a worsted yarn. The knitting defects due to the knots are caused by end breakages in the 1×1 rib knitting zone which almost lead to holes in knitted fabrics. This end breakage occurs near the knot on the take-down side. When the depth of stitch draw, the input tension, the take-down weight and the step length of cam are increased or when the cam angle is decreased, the end breakage rate in the 1×1 rib knitting zone increases.

Comparision of End Breakage Rates in a Plain-Weft Knitting Zone due to Splices and Knots

The effect of some knitting factors such as the machine gauge, the depth of stitch draw, the input tension, and the take-down weight on the end breakage rates in plain-weft knitting zone due to yarn joints (airsplices, weavers knots and fisherman's knots) is investigated experimentally, using a cotton yarn (30s/1).The results obtained are as follows : (1) The knitting defect due to airsplices is hardly occurred for every knitting condition. Airsplice is a very usefull yarn joint on weft knitting.(2) The knitting defect due to weavers knots or fisherman's knots almost causes knitting holes by end breakages in a plain-weft knitting zone. The end breakage occurs near the knot on the take-down side.(3) The end breakage rate in a plain-weft knitting zone due to weavers knots or fisherman's knots increases together with the increase of the machine gauge, the depth of stitch draw, the input tension, and the take-down weight.(4) For every knitting condition, the end breakage rate in plain-weft knitting zone due to fisherman's knots is more than that due to weavers knots.

Spin Finishes for Cotton

Cotton has an exceptional natural finish, but under adverse conditions of weathering, this finish may deteriorate to the extent that processing quality is altered. Changing technologies involving higher processing speeds and new spinning systems have placed increased demands on the fiber properties of all cottons. Spin finishes could reasonably improve the processing qualities of both damaged cottons and cottons in general. The history of effective finish usage (additives) in both ginning and textile processing of cotton has been reviewed. Cottons harvested both before and after significant weathering in the Mississippi Delta, with and without added finishes, were evaluated for spinning quality. The cottons harvested before and after weathering had similar traditional fiber properties of length, strength, and micronaire, but the weathered cottons were poorer in grade, color, and trash. The processing performance of the unweathered cottons was superior to that of the weathered cottons. A hydrocarbon plus surfactant additive improved the processing performance of the weathered cottons in relation to processing waste and dust generation, but did not improve spinning end breakage or yarn strength.

Factors Affecting Defects in 1 X 1 Rib Knitted Fabrics due to Knots of Spun Yarns

The effects of some factors on the defects in 1 X 1 rib knitting due to knots are investigated experimentally, using a cotton yarn (c30s/1) and a worsted yarn (2/72s).The results obtained are as follow : (1) The knitting defect due to the knots is almost the knitting hole caused by end breakages in 1 X 1 rib knitting zone. The end breakage occurs near the knot on the take-down side.(2) The end breakage rate increses together with the increase of the depth of stitch draw, the input tension, the take-down weight and the step length of cam. But the increase of the cam angle decreases the end breakage rate.

Factors Affecting Defects in Plain-Weft Knitted Fabrics due to Knots of Spun Yarns

The effects of some factors on the defect in plain-weft knitting due to knots are investigated in detail, using a cotton yam and a worsted yarn. The results obtained are as follows:(1) The knitting defect due to the knot is almost the knitting hole caused by the end breakage in plain-weft knitting zone. The end breakage occurs near the knot on the take-down side.(2) The end breakage rate increases together with the increase of the depth of stitch draw, the input tension, the take-down weight, the machine gauge, the coefficient of yarn friction, the step length of cam, and the machine speed. But the increase of the cam angle decreases the end breakage rate.