Impact of Carding Parameters and Draw Frame Doubling on the Properties of Ring Spun Yarn

Transcription

1 Impact of Carding Parameters and Draw Frame Doubling on the Properties of Ring Spun Yarn Abdul Jabbar, Tanveer Hussain, PhD, Abdul Moqeet National Textile University, Faisalabad, Punjab PAKISTAN Correspondence to: Tanveer Hussain ABSTRACT The impact of card cylinder speed, card production rate and draw frame doubling on cotton yarn quality parameters was investigated by using the Box- Behnken experimental design. It was found that yarn tenacity, elongation and hairiness increase by increasing the number of draw frame doubling up to a certain level and then decrease by further increase in doubling. Yarn unevenness increased by increasing card production rate and total yarn imperfections increased by decreasing card cylinder speed and increasing card production rate. Keywords: Spinning; carding; drawing; cotton yarn INTRODUCTION Ring spinning is one of the most commonly used spun yarn manufacturing technologies for producing high strength carded and combed cotton yarns in the widest range of linear densities. Various processes involved in the spinning of carded spun yarn include cleaning and blending cotton in the blow room, carding, breaker and finisher drawing, roving formation on the simplex and yarn formation on the ring frame. The effect of different parameters of these processes on the resulting yarn quality, have been studied by various researchers in the past. The effect of fiber opening in the blow room on the yarn quality has been studied and it has been found that increase in fiber opening in the blow room results in improvement in yarn tenacity and yarn imperfections (IPI) up to a certain level of opening, beyond which these parameters deteriorate sharply [1]. Similarly, fiber openness at carding also results in improvement in yarn irregularity and tenacity only up to a certain level and then these parameters deteriorate on further increase in fiber openness []. Card draft, coiler diameter and draw frame delivery speed are also found to have significant effect on yarn properties. It has been reported that yarn tenacity, breaking elongation, evenness and hairiness are improved with increase in card coiler diameter and draw frame delivery speed, and that an increase in card draft beyond a certain point leads to deterioration in yarn quality [3]. The percentage of leading and trailing fiber hooks in the roving fed to the ring frame also affects the yarn quality. It has been found that percentage of trailing, leading and total fiber hooks decrease with the increase in card coiler diameter, card draft, and draw frame delivery speed [4-5]. The effect of lap hank, card draft, speed frame draft, and ring draft on the physical and tensile properties of yarns has also been investigated. It was found that yarn spun at higher speed frame draft and corresponding lower ring frame draft has better tenacity, breaking elongation and evenness in comparison to yarn spun at lower speed frame draft and higher ring frame draft. It was also noted that card draft followed by lap hank is a major contributing factor influencing the changes in yarn properties [6-7]. Increasing carding rate and total spinning draft improves the yarn strength and evenness, whereas lowering spindle speed results in a stronger and more uniform yarn with fewer imperfections [8]. The influence of spindle speed on yarn strength, breaking elongation, imperfections and hairiness has also been investigated. It has been reported that the yarn tenacity improves whereas imperfections, hairiness and breaking elongation deteriorate with the increase in spindle speed [9]. The influence of fiber friction, top arm pressure, and roller settings at various drafting stages, namely, draw frame, roving frame, and ring frame has also been studied [10], and it has been found that top arm pressure and roller settings at all three drafting stages affect the yarn properties in a similar way, and that fiber-to-fiber friction is a leading factor influencing the tensile properties of ring spun yarn. Journal of Engineered Fibers and Fabrics 7 Volume 8, Issue 013

2 The carding process has a vital role in the production of staple spun yarn and has significant effect on the properties of the resulting yarn. In addition, drawing and doubling at the subsequent production stages also play an important role in determining the consequent yarn quality. It is evident from the literature review that previous work does not reveal the impact of preparatory process variables such as card cylinder speed, production rate, and number of draw frame doubling on the quality of ring spun yarn. This study was carried out to fill this gap using the Box Behnken statistical design of experiments. MATERIALS AND METHOD Three process variables, card cylinder speed (rpm), card production rate (kg/hr), and number of doublings at breaker drawing, were selected for experimentation. Coded levels and actual values of these variables are given in Table I. TABLE I. Experimental factors and their levels. Yarn samples were prepared according to the combinations of different factor levels as determined by Box-Behnken factorial experimental design. Box- Behnken is one of the most advanced response surface methodology (RSM) experimental designs employed to understand the quantitative relationships between multiple input variables and response variables. Pakistani Cotton with upper half mean length of 7.18 mm, strength of 31.5 g/tex, elongation of 5.8 %,and micronaire of 4.6 µg/inch respectively, was used to prepare the yarn samples of 4 tex linear density. All yarn samples were prepared by using Reiter C 60 Card, Reiter SB- Breaker Draw Frame, Reiter RSB- 35 Finisher Draw Frame, FA 458ASpeed Frame, and FA 150 Ring Frame. The linear densities of the prepared card sliver, finished sliver, and roving were 6.38 ktex, 5.95 ktex, and ktex respectively. The yarn samples of 4tex were prepared from these rovings at a spindle speed of rpm with a twist multiplier of Before testing, all the prepared yarn samples were conditioned in the laboratory under standard atmospheric conditions of 1±1 C and a relative humidity of 65± for 4 h. A Zweigle G 566 hairiness tester was used to measure distribution of hairs per unit length on the yarn surface according to ASTM D Only the hairiness parameter S 3 (number of hairs greater than 3mm) was considered, which is known to significantly affect the appearance and performance of yarns. Yarn unevenness and imperfections were determined by using Uster Tester-4 according to ASTM D Total yarn imperfections (IPI) were calculated by adding -50% thin, +50% thick and +00% neps. A Uster Tensojet-4 was used determine the breaking elongation and tenacity of yarn samples according to ASTM D-76. RESULTS AND DISCUSSIONS The complete Box-Behnken experimental design and the yarn test results are given in Table II. The experimental design and statistical analyses were performed using the Minitab16 statistical software package. The regression coefficients and p-values of all the terms are given in Table III. The terms with p- values less than 0.05 are considered statistically significant with 95% confidence. The regression equations, considering the actual values of input variables, are given in Table IV for all the response variables. The R values give the percentage of variation in the response variables that can be explained by the factors/terms included in the regression equations. The impact of all the factors on each response variable is separately discussed in the following sections. Journal of Engineered Fibers and Fabrics 73 Volume 8, Issue 013

3 TABLE II. Box-Behnken experimental design and yarn test results. S. No. Factors/Input Responses/Output variables x 1 x x 3 Hairiness (S 3 ) U m (%) IPI Elongation (%) Tenacity (RKM) TABLE III. Regression coefficients for different response variables using coded values of the input variables. Term Hairiness (S 3 ) Um% IPI Elongation (%) Tenacity (RKM) Coeff. P-Value Coeff. P-Value Coeff. P-Value Coeff. P-Value Coeff. P-Value x * x * * x x x x * * * x 1 x x 1 x x x *Statistically significant terms TABLE IV. Regression equations for different response variables using actual values of the input variables. No. Yarn properties Regression equation R (%) 1 Hairiness x x +894.x x x x x 1 x -0.18x 1 x x x 3 Um% x x -1.34x x 1 * x x 3-7.5x 1 x * x 1 x 3 * x x IPI x x x x x x x 1 x x 1 x x x 3 4 Elongation (%) x x +6.80x x 1 * x -0.54x x 1 x * x 1 x x x 3 5 Tenacity (RKM) x x x x x -1.4x x 1 x * x 1 x x x 3 Yarn Hairiness Surface plots depicting the effect of card production rate, card cylinder speed, and draw-frame doubling on yarn hairiness are given in Figure 1(a, b, c). It is clear from the Figure 1(b, c) that yarn hairiness increases with the increase in draw frame doubling up to a certain point and then decreases with any further increase in this parameter. Hairiness is low when the draw frame doubling is 5 or 7, while it is higher when the draw frame doubling is 6. If we look at Table II, the hairiness values vary from to 1643 at different combinations of input variables, with draw frame doubling (x 3 ) being the main Journal of Engineered Fibers and Fabrics 74 Volume 8, Issue 013

4 influencing factor. The average hairiness for experiments with 5 doublings is 661, for experiments with 6 doublings it is 1365 and for 7 doublings it is 814. This difference is not just statistically significant but also practically significant. The yarns with high hairiness may result in a greater amount of fabric pilling and surface fuzziness as compared to the yarns with lower hairiness. The trend in the results may be explained by a decrease in inter-fiber cohesion with the increase in doubling from 5 to 6, due to fibers straightening up to a doubling level of 6. Less inter-fiber cohesion allows the fibers to easily come out from the fiber strand leading to increase in yarn hairiness. Beyond the doubling level of 6, fiber parallelization decreases with an increase in sliver weight resulting in increase in inter-fiber cohesion. The effect of card production rate and cylinder speed on yarn hairiness was not found to be statistically significant with 95% confidence level (p-value > 0.05, Table III). FIGURE 1. Effect of card cylinder speed, card production rate and draw frame doubling on yarn hairiness. Yarn Unevenness Figure (a, b, c) depicts the effect of card cylinder speed, card production rate, and draw frame doubling on yarn unevenness. It is clear from Figure (a, c) that yarn unevenness increases with an increase in the card production rate. As the card production rate is increased from 80 to 10 kg/hr, there is a steady increase in the yarn unevenness (Um%) from an average value of 11.5 at 80 kg/hr production rate to 1.1 at 10 kg/hr production rate. It is evident from the trend that the yarn unevenness is directly proportional to the card production speed and the spinner should increase the card production rate with caution. The trend in the results can be explained as follows: the higher production rate results in poor carding, higher cylinder-loading and more leading fiber-hooks in the carded sliver. Ultimately, roving with higher leading fiber-hooks is forwarded to the ring frame contributing to an increase in yarn unevenness. The effect of card cylinder speed and the draw frame doubling was not found to be statistically significant (p-value > 0.05, Table III). According to the existing theoretical models published on the effect of doubling on mass irregularity, the yarn unevenness decreases by increasing the number of doublings [11]. This decreasing trend can be seen in Figure b at 900 rpm. However, the effect was not found to be statistically significant in the present study when the number of doubling is increased from 5 to 7. One reason for a little deviation from the theoretical models may be that the theoretical models assume the card production rate and cylinder speed to be same for different number of doublings while in the present study, those factors were also taken as the input variables. Journal of Engineered Fibers and Fabrics 75 Volume 8, Issue 013

5 FIGURE. Effect of card cylinder speed, card production rate and draw frame doubling on yarn unevenness. Total Yarn Imperfections Surface plots expressing the effect of card production rate, card cylinder speed, and draw frame doubling are shown in Figure 3(a, b, c). It is evident from Figure 3 (a, b, c) that total yarn imperfections (IPI) increase as the card production rate increases from 80 kg/hr to 10 kg/hr, and also as the card cylinder speed decreases from 900 rpm to 700 rpm. An increase in card production rate results in a heavier operational fiber layer on the card cylinder surface, higher cylinder loading, and more nep generation due to poor carding action. Hence, the poor carding action at higher production rate results in higher total yarn imperfections. The decrease in total imperfections with the increase in card cylinder speed can be explained by good carding and nep removal at the carding stage. At higher carding-cylinder speeds, better carding action results in a decrease in total yarn imperfections. A variation in total imperfections from 77 to 61 (see Table II) with different combinations of input variables is not just statistically significant but also practically significant. A yarn with higher number of yarn imperfections will ultimately result in poor fabric appearance. The average value of IPI is 504 with experiments having 700 rpm card cylinder speed, and 375 with experiments having 900 rpm cylinder speed. Such a difference is both statistically and practically significant. Similarly, average value of IPI is 341 with experiments having 80kg/hr production rate, and 547 with experiments having 10 kg/hr production. Again, such a difference is both statistically and practically significant. Draw frame doubling was not found to have a statistically significant effect on total yarn imperfections (p-value > 0.05, Table III). FIGURE 3. Effect of card cylinder speed, card production rate and draw frame doubling on yarn imperfections (IPI). Yarn Breaking Elongation Figure 4(a, b, c) depicts the effect of card cylinder speed, card production rate and draw frame doubling on breaking elongation of the yarn. It is clear from Figure 4(b, c) that as the draw frame doubling increases, breaking elongation of yarn increases upto a certain point and then decreases with a further increase in doubling. Yarn breaking elongation is higher when the draw frame doubling is 6, while it is lower when the doubling is 5 or 7. This behavior can be explained by the improvement in fiber parallelization due to increase in draft up to 6 doublings. After that when the doubling is further increased to 7, fiber parallelization decreases due to too large an increase in sliver weight. Increase in fiber parallelization in sliver improves the yarn breaking elongation. The results at different combinations of input variables show a variation in Journal of Engineered Fibers and Fabrics 76 Volume 8, Issue 013

6 elongation from 3.6% to 4.4%. This difference is not just statistically significant but also practically significant. The higher the yarn elongation%, the better it will be able to withstand stresses during weaving, resulting in less yarn breakages on the loom and higher weaving efficiency. The effect of cylinder speed and production rate on yarn breaking elongation was not found to be statistically significant (p-value > 0.5, Table III). FIGURE 4. Effect of card cylinder speed, card production rate and draw frame doubling on yarn breaking elongation. Yarn Tenacity Surface plots in Figure 5(a, b, c) show the effect of card cylinder speed, card production rate, and draw frame doubling on the yarn tenacity. It can be seen from Figure 5(b, c) that the yarn tenacity increases with an increase in draw frame doubling up to a certain level and then decreases with a further increase in doubling. Yarn tenacity is higher when the draw frame doubling is 6, while it is lower when the doubling is 5 or 7. Sliver doubling improves fiber straightening and parallelization by the increase in draft up to a certain level and beyond that level, fiber parallelization decreases with an increase in sliver weight due to the increase in sliver doubling. Hence, at an appropriate level of doubling of 6, the fiber parallelization is optimal, resulting in high yarn tenacity. Although the improvement in yarn tenacity at 6 doublings does not in itself look much as compared to 5 or 7 doublings, when combined with the simultaneous improvement in yarn elongation as discussed in the previous section, it plays a significant role in reducing the yarn breakages on the loom, thus increasing weaving efficiency. According to the analysis of variance, the effect of card production rate and card cylinder speed was not found to be statistically significant on the yarn tenacity (p-value > 0.5, Table III). FIGURE 5. Effect of card cylinder speed, card production rate and draw frame doubling on yarn tenacity. CONCLUSIONS Increase in card cylinder speed significantly decreases the yarn IPI, without significantly affecting any other yarn parameter. An increase in card production rate results in a significant increase in yarn IPI as well as yarn unevenness. The number of draw frame doublings not only significantly affecst the yarn tenacity and elongation, but also yarn hairiness. However, the effect of draw frame doubling is not linear. By increasing the number of doubling up to a certain level, the yarn tenacity, Journal of Engineered Fibers and Fabrics 77 Volume 8, Issue 013

7 elongation and hairiness increase, but on a further increase in number of doubling, the trend is reversed. ACKNOWLEDGEMENT The authors would like to thank Mr. Shahzad Hashmi, General Manager Best Exports (Pvt) Ltd Faisalabad for providing opportunity and support to prepare yarn samples for this study and Mr. Asif Javed General Manager Nishat Mills Ltd unit #1 Faisalabad for providing the facility of testing yarn samples. REFERENCES [1] Ishtiaque, S. M.; Chaudhuri, S.; and Das, A.; Influence of fiber openness on processibility of cotton and yarn quality. Part I: Effect of blow room parameters Indian Journal of Fibre & Textile Research, 8, 003, [] Ishtiaque, S. M.; Chaudhuri, S.; and Das, A.; Influence of fiber openness on processibility of cotton and yarn quality. Part II: Effect of carding parameters Indian Journal of Fibre & Textile Research, 8, 003, [3] Ishtiaque, S. M.; Mukhopadhyay, A.; and Kumar, A.; Influence of drawframe speed and its preparatory on ring yarn properties Journal of the Textile Institute, 99, 008, [4] Garde, A. R.; Wakankar, V. A.; and Bhaduri, S. N.; Fiber configuration in sliver and roving and its effect on yarn quality Textile Research Journal, 31, 1961, [5] Ishtiaque, S. M.; Mukhopadhyay, A.; and Kumar, A.; Impact of carding parameters and drawframe speed on fiber axial distribution in ring spun yarn Indian Journal of Fibre & Textile Research, 34, 009, [6] Kumar, A.; Ishtiaque, S. M.; and Salhotra, K. R.; Analysis of spinning process using the Taguchi method. Part IV: Effect of spinning process variables on tensile properties of ring, rotor and air-jet yarns Journal of the Textile Institute, 97, 006, [7] Kumar, A.; Ishtiaque, S. M.; and Salhotra, K. R.; Analysis of spinning process using the Taguchi method. Part V: Effect of spinning process variables on physical properties of ring, rotor and air-jet yarns Journal of the Textile Institute, 97, 006, [8] Lee, J. R.; and Ruppenicker, G. F.; Effect of precessing variables on the preperties of cotton knitting yarns Textile Research Journal, 48, 1978, [9] Lawal, A. S.; Nkeonye, P. O,; and Anandjiwala, R. D.; Influence of spindle speed on yarn quality of Flax/Cotton blend The Open Textile Journal, 4, 011, 7-1 [10] Das, A.; Ishtiaque, S. M.; and Niyogi, R.; Optimization of fiber friction, top arm pressure and roller setting at various drafting stages Textile Research Journal, 76, 006, [11] Martindale, J.G.; A new method of measuring the irregularity of yarns with some observations on the origin of irregularities in worsted slivers and yarns, Journal of the Textile Institute, 36, 1945, T AUTHORS ADDRESSES Abdul Jabbar Tanveer Hussain, PhD Abdul Moqeet National Textile University Sheikhupura Road Faisalabad, Punjab PAKISTAN Journal of Engineered Fibers and Fabrics 78 Volume 8, Issue 013