CHAPTER - 2 RING & COMPACT YARN TECHNOLOGY

Transcription

1 CHAPTER - 2 RING & COMPACT YARN TECHNOLOGY 2.1 Introduction Several Researchers have shown that compact yarn have greater evenness of structure and reduced hairiness as compared to ring yarn. Artz [135] studied yarn properties of compact yarn and conventional ring spun yarn. He found that compact yarn is having greater strength, better evenness and elongation properties. On the other hand, some investigators have indicated that the same strength can be achieved with lower twist values and therefore, it results in higher productivity. Krifa and Ethridge [136] defined the necessary fibre properties for this system. Mahmood et al [137] studied the effect of spinning parameters on yarn hairiness. Yarn structure and the performance of compact yarns in downstream processes have been investigated and the benefits of compact yarn in winding, sizing, singeing, doubling, weaving, and knitting have been reported in research studies. Dash et al [139] studied their performance in winding. Krifa et al [136] compared the performance of ring spun and compact yarns spun from various staple length of fibres. Artzt [138] and [142 to157]indicated the advantages of this system for combed yarns. Behera et al. [143] studied the performance of compact yarns in weaving and showed reduced warp end breakage rate. Compact spinning is an improvement over ring spinning system that has recently been developed. The yarns spun by this system have been reported as superior to ring-spun yarns. Their running behaviour during downstream processing stages as well as the wear properties of the products produced from them has been found to be favourable, due to their superior quality in terms of better tensile strength and elongation, reduced hairiness and higher abrasion resistance. However, few researchers have reported that the dyes do not penetrate into the yarn core instead dye is deposited on the surface only. The work in the field of chemical treatments in 65

2 relation to processing parameters and their effect on processing performance of compact yarns is scanty. 2.2 Material and Experimental Methods: Material: Table: 2.1 Properties of MCU -5 Cotton Fibre. Span Span Uniformity Strength Elongation Micronaire Light Yellowness Short length length Ratio Value & fibre Dark index 2.5 % SL 50% SL UR % STR ELG MIC RT +B SFI Methods: : Manufacturing of Ring yarn. Blow Room Carding Draw Frame Super-Lap Comber First passage Draw Frame Second passage Draw Frame Roving Frame Ring Frame Autoconer Winding 66

3 : Manufacturing of Compact yarn. Blow Room Carding Draw Frame Super-Lap Comber First passage Draw Frame Second passage Draw Frame Roving Frame Ring Frame COM-4 Autoconer Winding All RIETER brand machinery were used to spin 40 s Ring and 40 s Compact yarn : Testing Machines and procedures: Ring yarn and compact yarn were conditioned at 27 0 C temperature, 65 % R.H., for 48 hours. Test method for Unevenness percentage of yarn ( ASTM- D ): The Uster Tester 3 V2.42 machine is based on capacitance principle. A variation in the mass of material per unit length produces corresponding variations in the capacity of the condenser. Unevenness percentage of yarn is measured after machine warm-up and conditioning for 30 minutes. The measuring slot is selected as per the count of yarn. Ring Yarn of 40 s count and compact yarn of 40 s count (100 % Cotton) are tested at the speed of 50 m/min using Range of Scale (100 %). Switch the machine to NORMAL mode. Select sensitivity as: Thin ( 50), Thick (3) and Neps (3). Mean values of U % (8 mm, 100 meters), C.V. %, Thick places, Thin Places and Neps are obtained per 1000 meters of yarn. 67

4 Tenacity of yarn (ASTM D ): Uster Tensorapid 3 V 5.4 is used for testing tenacity of the yarn. This machine works on the principle of constant rate of elongation. The test sample is fixed between two clamps. The sample is elongated at a constant rate. Bottom clamp moves downward at constant rate as screw- rod rotates with constant revolutions per minute. As the extension continues, the tension in the sample reaches to its maximum value and it breaks at weakest point. A care is taken during yarn withdrawal that yarn path should not be obstructed. Testing speed used is 5000 mm per minute. Testing yarn length is 500 mm. While pretension of 0.5cN/tex is applied during 100 tests taken, separately for 40 s compact yarn and 40 s ring yarn. Mean values and C.V. % of tensile strength and elongation are calculated. Seldom occurring Faults: Machine - Classifault Model CFT-II, is used to find out Seldom occurring Faults from 40 s Ring Yarn and 40 s compact yarn (100 % Cotton).These faults are classified according to the cross-sectional size and shape of the fault by an electrode of length 9 mm. The testing speed is 540 m/min. Total length of 5 km is tested. These faults are further separated as Short thick places (A1 to D4) Long thick places (E, F and G) and long thin places (H1, H2, I1 and I2). 68

5 2.3. Results and Discussion: Ring Yarn Unevenness: Table 2.2 [A] Testing of Unevenness in Ring yarn (40 s ) U% CVm% CVm Thin Thin Thin (10m) (-30%) (-40%) (-50%) Mean / km 79 / km 3/km CV% Table 2.2 [B] Testing of Unevenness in Ring yarn (40 s ) Thick Thick Thick Neps Neps Hairiness S.D. of (+35%) (+50%) (+70%) (+140%) (+200%) Hairiness Mean 267/km 20/km 2/km 243/km 51/km CV% Table 2.2 [A] and [B] show ring yarn Unevenness of 40 s count tested on Uster tester 3.v It shows that yarn unevenness (U %) is 10.6/ km. It can be observed that thin places (-50 %) are found to be 3/km. Similarly, thick places (+50%) are found to be 20/km. Further Neps (+200%) are found to be 51/km. 69

6 2.3.2 Compact yarn Unevenness: Table 2.3 [A] Testing of Unevenness in Compact yarn (40 s ) U% CVm% CVm Thin Thin Thin (10m) (-30%) (-40%) (-50%) Mean / km 55 / km 1 / km CV% Table 2.3 [B] Testing of Unevenness in Compact yarn (40 s ) Thick Thick Thick Neps Neps Hairiness S.D. of (+35%) (+50%) (+70%) (+140%) (+200%) Hairiness Mean 206 /km 21/ km 4/ km 242/ km 65/ km CV% Table: 2.3 [A] and [B] show unevenness in 40 s compact yarn, tested on Uster tester 3V2.42. It shows that Unevenness (U %) is 9.76 per km of compact yarn. It is can be observed that thin place (-50%) is 01/km and thick places (+50%) are 21/km. Further, Neps (+200%) are found to be 65/km. From the above results it can be seen that, compact yarn has 15 to 20 % less total imperfections than ring yarn. It may be due to special suction and condensation of fibres which reduces flying of short fibres and reduction in spinning triangle of compact yarn during spinning process as compared to ring yarn spinning triangle at ring frame. 70

7 Studies In Mercerization Graph 2.1 Analysis of Yarn Unevenness, Thin places, and thick places in Ring Yarn and Compact Yarn Ring yarn Compact yarn U% Thin places (- 50%) Thick places (+50%) In the case of compact yarn, Imperfections, Unevenness and thin places are found to be lesser than ring yarn. However, thick places are found to be almost same as compared to ring yarn. Graph 2.2 Analysis of Neps and Imperfections in Ring Yarn and Compact Yarn Neps (+200%) Total Imperfections Ring yarn Compact yarn It is observed from Graph 2.2 that Neps (+200%) and total Imperfections are higher in compact yarn. 71

8 2.3.3 Tenacity of Ring Yarn: Table 2.4 Ring Yarn Breaking Force & Elongation Time to Breaking Elongation at Rkm Work at Break Break (sec) Force (N) Break (%) (Kgf*Nm) (N.Cm) Mean SD CV% Table: 2.4 gives ring yarn breaking force and elongation tested at 5000 mm / min on Uster Tensorapid 3 V5.4 machine. Breaking force required is 2.51N and elongation at break is 4.21%. Tenacity is (Rkm) kgf. Nm. Coefficient of variation of Breaking force and elongation are 7.08%, and 8.88%, respectively Tenacity of Compact yarn: Table 2.5 Compact yarn Breaking force and Elongation Time to Breaking Elongation Rkm Work at Break Break (sec) Force(N) (%) (Kgf*Nm) (N.Cm) Mean SD CV% Table: 2.5 gives compact yarn breaking force and elongation of 40 s count, tested at the speed of 5000 mm/minute on Uster Tensorapid 3V 5.4 models. It shows breaking force required is 3.05 (N) and elongation at break is 4.84%. The Rkm is found to be 21.05( kgf.nm). Similarly, the coefficient of variation percentage of breaking force and elongation are 14.71% 14.67% respectively. 72

9 Studies In Mercerization Table 2.6 Comparison of Tensile Properties of Ring and Compact Yarn Breaking Force (N) Elongation % RKm Kgf*Nm Ring yarn Compact yarn Ring yarn 20 Compact yarn Breaking Force Elongation % (N) RKm Kgf*Nm Graph 2.3: Comparison of breaking force, elongation and RKm values of Ring yarn and compact yarn. It is observed from Graph 2.3 and Table 2.6 that Breaking force, Elongation and RKm values for compact yarn are higher as compared to those of ring yarn. This may be due to short fibres flying out in ring spinning system. In compact yarn spinning process short fibres do not fly out,rather they are used in yarn preparation. Similarly, parallel arrangement of fibres and higher fibre migration in compact spinning system higher Breaking force, Elongation and RKm values are observed for compact yarn. 73

10 2.3.5 Ring yarn Faults classification: Table 2.7 Ring yarn faults classification/100km Fault Slub Class A B C D E No. of Cut Drum No. Number of Cut Working Time (Sec.) % % % % Total Thick F G H I J +45% % Thin K L M N O -20% % Table: 2.7 Shows ring yarn faults classification per 100 km. as tested on Classifault Model CFT II. This is tested at speed of 540 meters/minute. Total yarn length tested is 500 km. Faults in these classes (H.J.M.N. O, D & E) are absent. Long thick, long thin faults and objectionable faults are zero. It shows that yarn quality is good. 74

11 2.3.6 Compact yarn faults classification: Table 2.8 Compact yarn faults classification/100km Fault Slub Class A B C D E No. of Cut Drum No. Number of Cut Working Time (Sec.) % % % % Total Thick F G H I J +45% % Thin K L M N O -20% % Table: 2.8 Shows compact yarn faults classification/100km as found by Classifault model CFT II. It is carried out at a speed of 540 meters/min. Total length tested is 500 km. It shows zero faults in category of thin faults (L, M, N, O, & D) and objectionable faults. It shows that yarn quality is good. 75

12 Studies In Mercerization Table 2.9 Fault Slub from Ring Yarn and Compact Yarn Fault Slub Fault Slub Fault Slub Fault Slub +100 % +150% +250% +400% Ring Yarn Compact Yarn Ring Yarn Compact Yarn Fault Slub +100 % Fault Slub +150% Fault Slub +250% Fault Slub +400% Graph 2.4 Comparison of Fault Slub from Ring and Compact Yarn. Graph 2.4 and Table 2.9 show that fault Slubs are higher in ring yarn (100%, 150%, and 250%) as compared to compact yarn. It can be observed that parallel arrangement of fibres in compact yarn spinning system gives minimum fault Slub as compared to ring yarn. 76

13 Studies In Mercerization Table 2.10 Comparison of Thick Places from Ring Yarn and Compact Yarn Ring Yarn Compact Yarn Thick Places (+20%) Thick Places (+45%) Thick Places (+20%) Thick Places (+45%) Ring Yarn Compact Yarn Graph 2.5 Comparison of Thick Places Thick places from Ring and Compact yarn Graph 2.5 and Table 2.10 show that compact yarn has lesser number of thick places for both (+20%) and (+45%) as compared to thick places in ring yarn. 77

14 Studies In Mercerization Table 2.11 Comparison of Thin Places from Ring Yarn and Compact Yarn Ring Yarn Compact Yarn (-20%) (-30%) Ring Yarn Compact Yarn (-20%) (-30%) Graph 2.6 Comparison of Thin places from Ring and Compact Yarn. Graph 2.6 and Table 2.11 show that (-20%) and (-30%) thin places are on higher side in ring yarn as compare to thin places in compact yarn. This may be the result of uniform condensation of fibres due to special suction system used in compact yarn spinning process. 78

15 Studies In Mercerization 2.4 Ring and Compact Yarn Images: Ring and Compact Yarn Images Figure 2.1 From the above image it can seen that compact yarn shows less hairiness than of ring yarn. The fibres in the compact yarn are better oriented towards the axis of the yarn as compared to ring yarn structure. 2.5 Conclusion: Breaking force required for compact yarn is 3.5(N) while for ring yarn breaking force required is 2.51(N).Thus 40 % higher breaking strength for compact yarn is observed. Elongation percentage for compact yarn is 4.84% while for ring yarn it is 4.21% %. Thus compact yarn shows 14 % higher elongation in comparison to ring yarn. 79

16 In the case of compact yarn, hairiness index observed is 3.6 while for ring yarn it is 4.4. Thus about 30% reduction in hairiness is obtained for compact yarn. Yarn unevenness for 40s ring yarn is 10.6 (U %) while unevenness for 40s compact yarn is 9.76 (U %), showing 10% improvement in evenness. Thin places (-50%) are 3/km and 1/km for ring and compact yarn respectively, thereby showing reduction by 66% in thin places for compact yarn. Objectionable faults (A4+B4+C4+D4+C3+D3) for the ring yarn are 0.9. While for compact yarn they are 1.8. However, difference is not much significant. Thick places (F+G+H+I+J) observed for ring yarn are 46 while for compact yarn thick places are found to be 37.9 showing reduction by 16% thick places in compact yarn. Thin places (K+L+M+N+O) are 8.0 for ring yarn and 4.5 for compact yarn showing reduction by 50 %. 80