Twist Multiplier Research Articles

Effect of Varying the Twist Multiplier of Open-End Yarn on Pilling and Other Fabric Properties

Pilling has been one of the major consumer problems of man-made staple yarn products. This study evaluated the pilling performance of 65/35% Dacron/cotton fabrics woven from open-end (OE) yarns by the Random Tumble Pilling Tester Method (ASTM Test Method D3512-82) and the Elastomeric Pad Method (ASTM Test Method D3514-81) at five specified test intervals. The effect of twist level of warp and filling yarns on pilling propensity, flex abrasion, tensile strength, and breaking elongation was also investigated. Pilling produced by the Random Tumble Pilling (RTP) procedure was mainly fiber fuzz and loosely anchored pills; that produced by the Elastomeric Pad Method (EPM) was large scale pills and fiber entanglement which did not wear off readily. ANOVA test revealed that the twist level of warp yarns had a significant influence on thepilling characteristics as evidenced in both pilling tests. Twist level of filling yarns influenced EPMpilling ratings only intermittently. The effect of twist level of warp yarns was highly significant for the warp direction on flex abrasion, tensile strength, and breaking elongation. On the other hand the twist level of filling yarns influencedfilling tensile and breaking elongation. The major findings of the study indicate that pilling performance was significantly influenced by pilling test method and testperiod. The low and intermediate twist levels of OE yarns investigated did not consistently affect the pilling and other fabric properties analyzed.

The Influence of the Spinning Process, Yarn Linear Density, and Fibre Properties on the Hairiness of Ring-spun and Rotor- spun Cotton Yarns

Cotton–spun yarns from 34 staple stocks were manufactured by means of the ring–spinning process (34 yarns) and a rotor–spinning process (29 yarns) and tested for hairiness with the Shirley Hairiness Meter. For each spinning system, yarns were spun at two values of yarn linear density (15 and 30 tex for ring–spinning and 30 and 50 tex for rotor–spinning), but the twist multiplier was kept constant within the series for each spinning process. The higher hairiness of ring–spun yarns and an increase ln hairiness with the yarn linear density were confirmed. The effect of the fibre parameters on yarn hairiness explains only about 30% of the total effect for ring–spun yarns and 40% for rotor–spun yarns. Fibre length and its uniformity are the fibre properties having the greatest influence on the hairiness of both ring– and rotor–spun yarns, the Micronaire index having only slight influence on the hairiness of ring–spun yarn.

34—A CONTRIBUTION TO THE STUDY OF THE INFLUENCE OF THE DESIGN OF THE YARN-WITHDRAWAL TUBE ON THE DIAMETER AND HAIRINESS OF OPEN-END-SPUN ACRYLIC-FIBRE YARNS

An investigation is reported in which factorial experiments were conducted to study the influence of the design of the yarn-withdrawal tube (or nozzle) on the diameter and hairiness of open-end-spun acrylic-fibre yarns. Three nozzle types, combined with three values of yarn linear density and five values of twist multiplier, were studied for four different (but equal-diameter) rotor types. lt is shown that the nozzle type has very little influence on yarn diameter but has a more significant effect on yarn-hairiness parameters. As the nozzle diameter increases, yarn hairiness also tends to increase, but, when the nozzle is grooved, an interaction is produced between yarn friction and the false twist generated that leads to a yarn that is less hairy when tested on the Digital ITQT Hairiness Meter. The principle of measurement of the apparatus used can lead to different results and trends when applied to this problem.

Influence of a Yarn Extractive Nozzle on the Apparent Loss of Twist in Rotor Open-End Acrylic Staple Spun Yarns

The influence of a yam extractive nozzle on the apparent loss of twist or "residual twist" has been studied for rotor open-end acrylic staple spun yarns. Four factors were studied: two quantitative factors - yam linear density at three levels and yarn twist multiplier at five levels, and two qualitative factors - three nozzle types and four rotor types. The analysis of results showed that both rotor type and extractive nozzle type exert a significant influence on residual twist, which tends to increase when the nozzle produces an increasing false twist effect on the yam and to decrease when yarn friction against the rotor increases. Residual twist increases significantly in a linear manner with both yarn linear density and twist multiplier. The nozzle type interacts significantly with all other factors (rotor type, yam linear density, and twist multiplier). An inter action between yarn linear density and twist multiplier has been also detected. Generally both nozzle type and twist multiplier exert a significant influence on the residual twist coefficient of variation.

Dimensional and Physical Characteristics of Single Jersey Fabrics

An account is given of a study of the dimensional changes of plain weft knitted fabrics made from 12s, 16s, and 22s grasicrimp yam, brought about by various processes of relaxation including dry relaxation, wet relaxation, and tumble drying. In the dry relaxed state, the nature of knitted loop depends on the yarn's physical properties and knitting variables. After full relaxation, the values Kc, Kw, Ks, and Kc/Kw are independent of yarn or machine variables and approach a constant. In the full relaxed state, fabric thickness is independent of the tightness factor and depends on yam diameter and twists. The angle of wale lines with the vertical is increased with the twist multiplier and further increases after wet relaxation. Fabric bulk depends on loop length in all states of relaxation and has a linear relationship with the tightness factor after full relaxation.

Effect of Mercerization on the Tensile Properties of Rotor Spun Yarn

Rotor spun 14s cotton yarns were twisted over a range of twist multipliers from 4.25 to 5.5. The yarns were mercerized with sodium hydroxide and stretched to their original length. Tenacity of mercerized yarns was significantly greater than the grey yarns at all twist levels. A substantial improvement of 52.8% in tenacity was observed at the lowest twist. Even slack mercerization improved yarn tenacity at lower twist levels (up to 4.7) close to that for tension mercerized yam. Maximum increase in yarn tenacity by slack mercerization was 46% at the lowest twist. Tension mercerization increases yarn tenacity primarily by improvement of fiber packing at lower twist levels, but at higher twist levels fiber orientation, fiber packing, and improvement in fiber tenacity all affect yarn tenacity.

27—FACTORIAL STUDIES IN ROTOR-SPINNING PART III: ACRYLIC-FIBRE OPEN-END-SPUN YARNS

An investigation is reported of the effect of factors such as rotor diameter, rotor speed, and twist multiplier of acrylic-fibre open-end-spun yarn on the main yarn parameters, such as tenacity, elongation at break, irregularity, and quality index. Factorial experiments were used as the basis of the study. It is shown that, except for the influence of yarn twist, owing to the different characteristics of twist–strength curves and twist–elongation-at-break curves, the results are very similar to those from an earlier study on cotton yarns. For tenacity, the linear effects of yarn twist and rotor diameter and the quadratic effect of the latter are significant, there being no significant interactions. For elongation at break, the linear effects of rotor speed and rotor diameter and the quadratic effect of the latter are significant. There are several significant interactions. Not all of these present possibilities of being real interactions, some appearing to be chance interactions. Irregularity is significa...

Relation Between Twist and Abrasion Resistance of Rotor Spun Yarns

The relation between twist and abrasion resistance of polyester, polyester-cotton (50/50), and polyester-viscose (50/50) open end spun yarns was studied. The same trend observed in Part I of this study concerning cotton yams, viscose, and acrylic yarns is shown here. Abrasion resistance indefinitely increases with yarn twist (up to a twist multiplier of a = 200).

33—FACTORIAL STUDIES IN ROTOR-SPINNING PART I: COTTON YARNS

An investigation is described in which the effects of several factors, such as rotor diameter and rotor speed, twist multiplier and yarn twist, and type of draw-off nozzle, were studied in factorial experiments in which measurements were made of the main yarn parameters, such as tenacity, elongation at break, and regularity, and of the trash accumulated in the rotor. The experiments were made for cotton on two types of machine. Süssen and SKF. For twist values remote from the optimum twist, the linear and quadratic components of the twist multiplier affect the yarn tenacity, and its linear component affects the elongation at break; but, for values close to the optimum twist, the only significant effect is the linear influence on elongation at break. Yarn irregularity is significantly affected only by the twist multiplier. The rotor speed affects the tenacity, elongation at break, and yarn irregularity in a linear manner, but the rotor diameter affects these parameters both linearly and quadratically. The type of draw-off nozzle has only a slight effect on tenacity, whereas trash accumulation in the rotor is influenced by the linear components of both the twist and the rotor diameter. Some significant interactions were detected, which principally affect elongation at break generally, and trash accumulation in the rotor and tenacity when one of the interacting factors is the type of draw-off nozzle. The two machine types produced concurrent results.

13–A CONTRIBUTION TO THE STUDY OF THE HAIRINESS OF COTTON OPEN-END-SPUN YARNS PART II: THE INFLUENCE OF THE SPEED OF THE OPENING ROLLER ON YARN HAIRINESS FOR VARIOUS VALUES OF THE TWIST MULTIPLIER

SUMMARY The study reported in this paper concerns the influence of the opening-roller speed on the hairiness of cotton open-end-spun yarns for various values of the applied twist multiplier. The yarns analysed were processed through four different pre-spinning procedures, and hairiness was measured by means of the I.T.Q.T. Digital Hairiness Tester. The opening-roller speed does not influence yarn hairiness to a significant extent, but trends demonstrated in previous papers concerning the influence on yarn hairiness of the rotor diameter, the pre-spinning processes, and the twist are confirmed.

6–A CONTRIBUTION TO THE STUDY OF THE HAIRINESS OF COTTON OPEN-END-SPUN YARNS PART I: THE INFLUENCE OF THE ROTOR SPEED AND TWIST MULTIPLIER ON YARN HAIRINESS IN RELATION TO PRE-SPINNING PROCESSING

In this paper, the influence of the rotor speed and twist multiplier on cotton open-end-spun yarns in relation to pre-spinning processing is studied. Hairiness measurements were made by means of the Digital Hairiness Tester developed at the I.T.Q.T. Four different pre-spinning processes were used, some involving the suppression of the drawframes and the use of autolevellers in the cards. The nature of the pre-spinning process and the rotor diameter and speed affect the yarn hairiness. Yarn twist influences hairiness from certain values of the twist multiplier upwards.

23—THE RELATION BETWEEN THE TWIST AND RESISTANCE TO REPEATED EXTENSIONS OF MAN-MADE-FIBRE ROTOR-SPUN YARNS

The relation existing between the twist and resistance to repeated extensions of man-made-fibre rotor-spun yarns is studied. Experiments on acrylic-fibre, polyester-fibre, and viscose staple-fibre rotor-spun yarns are reported, and it is shown that, for these fibres, the maximum resistance to repeated extension is consistent with generally low twist multipliers, although the level of the resistance is dependent on both the fibre type and the linear density of the yarns. Some complementary tests concerning the relation existing between twist and tensile strength for cotton, polyester-fibre, and acrylic-fibre rotor-spun yarns are also reported. It is shown that, whereas for cotton yarns the twist for maximum strength is found for a high twist multiplier, for man-made-fibre yarns the optimum twist occurs at low values of the twist multiplier.

19—AN APPLICATION OF MINI-COMPUTERS TO THE OPTIMIZATION OF THE OPEN-END-SPINNING PROCESS PART XI: THE OPTIMIZATION OF THE OPENING-ROLLER SPEED AND TWIST FOR PROCESSING CONDITIONS REMOTE FROM THE OPTIMUM DURING THE ROTOR-SPINNING OF COTTON YARNS

The optimum values for both the opening-roller speed and the yarn twist, in operating with near-extreme values of both the total draft and the rotor speed, are studied. These values of draft and speed are, nevertheless, not uncommon in industry. For a total draft of 173 and a rotor speed of 45 000 r/min, and with a Sussen Rotorbox machine, it was found that the optimum values of yarn twist and opening-roller speed did not coincide with each other when either the yarn regularity or tenacity was considered as the most important parameter, a phenomenon that had, in fact, been observed earlier when all the operating parameters were optimized. In this instance, the best quality indices are obtained for opening-roller speeds above 6000 r/min and twist multipliers, a, of about 160 for a 23.57-tex yarn (N e = 25).

A Study How to Quantitatively Determine Crimps On Crape Fabrics

In order to quantitatively determine the crimps or waves of crape fabrics, we have analysed their appearance caused by shrinkages of single hard twist yarns and untwisting moment. The results are summerized: (1) The size of crape crimps is closely related to the number of spiral circles. Equation will be: m=0.2T/(1-f(s)) where m is the number of spiral circles: T, yarn twist and f(s), shrinkage of crape fabric. (2) The amplitude of crape crimps is related to the radius of spiral circles and given by the following formula: r=√<1-(1-f(s)2>)/ 0.4πT (3) The thickness of crape fabric is in proportion to the radius of spiral circles. It is greately influenced by the twist multiplier of hard twist yarns: (4) The degree of crimps, Ca-1, is a function of the fabric shrinkage as in the following formula; Ca-1 = A•f(s)5/2 where A is an experimental constant determined by the weft yarn arrangements.

46—AN APPLICATION OF MINI-COMPUTERS TO THE OPTIMIZATION OF THE OPEN-END-SPINNING PROCESS PART VI: THE INFLUENCE OF THE PARTIAL DRAFTS BETWEEN THE OPENING ROLLER AND THE ROTOR AND THE TOTAL DRAFT AND DOUBLING ON THE REGULARITY AND TENACITY OF OPEN-END-SPUN VISCOSE STAPLE-FIBRE YARNS

The application of the technique of Box and Hunter, combined with the use of a mini-computer, to the study of the relations between the total draft, the draft between the opening roller and the rotor, and doublings on the one hand and the regularity and tenacity of open-end-spun viscose staple-fibre yarns on the other permits graphs to be drawn that facilitate the determination of the optimum operating conditions as a function of the total draft (or linear density of the yarn). It Is shown that, in general, total drafts higher than 100 or a little more, partial drafts above 6, rotor speeds higher than 35 000 rev/min, and opening-roller speeds higher than 7000 rev/min are not suitable within the experimental zone explored. The optimum twist multiplier (α) is about 125.

41—AN APPLICATION OF MINI-COMPUTERS TO THE OPTIMIZATION OF THE OPEN-END-SPINNING PROCESS. PART II: CONSIDERATION OF THE CASE OF THREE VARIABLES

The application of a mini-computer to the analysis of three-variable experimental designs (speed of opening cylinder, rotor speed, and twist multiplier) is studied with reference to the spinning of polyester-fibre-cotton blends. A technological interpretation of the results obtained is given, which generally confirms earlier work and also contributes new details of the phenomena determining the observed behaviour.

The Effect of Certain Machine Parameters and Fiber Preparation on the Properties of Open-End Cotton Yarns

Cotton yarns of 32.81 tex with a twist multiplier of 4.0 were spun using six different drafts ranging from 86.54 to 140.63 on a Suesson Open-End Spintester from slivers that had been carded with and without crushrolls. The static pressure in the spinning chamber was held at two levels equivalent to 7.9 × 10−5 and 5.8 × 10−5 Pa. The spinning was performed at turbine speeds of 30,000, 45,000, and 60,000 rpm. Trash extracted by the machine was weighed after each spinning condition. Statistical analyses of data collected from yarn physical tests were performed. Analyses of variance results and graphical presentations are given. The results of the investigation indicate that increasing turbine speed deteriorates yarn physical properties significantly, but also results in more trash extracted; lower drafts yield better yarn evenness and fewer imperfections, but result in less waste extracted than the higher drafts; static pressure in the spinning chamber equivalent to 7.9 × 10−5 Pa results in better yarn evenness and fewer imperfections, but also decreases the trash removal efficiency; and the use of crushrolls at carding slightly lowers the tensile properites of the spun yarn. With respect to trash extraction, the visible foreign matter content of the slivers was lowered by the use of crushrolls; the data normalized to the foreign matter content show only a small effect due to the use of crushrolls at carding on the trash extraction efficiency of the system.

Effect of Spinning Draft Parameters on Cotton Drafting Efficiency

Studies of drafting force in the front drafting zone of the Saco-Lowell MagneCradle 17-B and Tru-Set drafting systems indicate that the MagneCradle 17-B, which uses higher roll pressure, has a greater tolerance for high roving twist, but this theory has not been tested in spinning. In both drafting systems, drafting force increases sharply in the high-force region where occasional hard ends begin to appear in the front roll delivery at a higher roving twist level in the Magne Cradle than in the Tru-Set system. Increasing break draft decreases drafting-force sensitivity to the effects of cradle opening and increases sensitivity to drafting failure, but drafting failure occurs at a higher roving twist level for the higher break draft. A series of yarn spinning studies with a wide range of yarn size shows that drafting force for minimum spinning end breakage decreases nonlinearly as yarn number is increased. Spinning tests show that increasing roving twist multiplier to 1.5 in medium-staple carded roving normally causes reduced spinning performance for the Tru-Set and MagneCradle 17-B systems, and the level of drafting force required to minimize the spinning end breakage is higher for the higher roving twist.

A Statistical Method of Characterizing Spinning Quality

This paper is concerned with a least squares iterative method of fitting data to a model developed by Bogdan [1] in his work on the determination of spinning quality Parameters. The model employed is of the form where count strength CS is the dependent variable, and twist multiplier M and count C are the independent variables. The parameters introduced have the following mean ing: β = obliquity parameter; ϕ = drafting parameter; π = intrinsic strength para meter; τ = ineffective twist parameter; α = cohesion parameter. An actual spinning quality parameter analysis is described in detail, and all results are tabulated. This method of analysis can serve as a useful tool in fiber development work. Parameter values that result from controlled changes in the physical properties of of the fiber can be used as a guide by the experimenter in determining his next course of action.

Influences of Fiber Properties on Yarn Twists

The variation in the twist multiplier for maximum yarn strength in terms of the fiber properties of length. weight fineness, and uniformity of tenacity along bundle length is inferred from data based upon 15 1, 30, 1, and 40/1 yarns of a series of cottons having widely different fiber properties. The optimum twist multipliers that were calculated (1) from the above three fiber parameters (i.e., the tenacity-length uniformity hypothe sis); (ii) from the length and fineness, and (III) from the fiber length alone are com pared to the optimum twist multipliers detemined from the yarn tenacity vs twist curves. The tenacity-length uniformity hypothesis and the Sullivan theory are com pared by utilizing single cotton fiber properties. Considering all comparisons, the cor relation coefficients for theoretical to nommal values of optimum twist range from 0.64 to 0.96. Utilization in yarn twist of the ratio denoting uniformity of tenacity along bundle length in the tenacity-length uniformity hypothesis and of the ratio of single-fiber tenacity transfer in the Sullivan theory is illustrated.