Indian Journal of Fibre & Textile Research Vol. 30, March 2005, pp. 26-31

Study on fibre openness - Its impact on roving drafting force and yam quality

S M Ishtiaque, K R Salhotra, A Dasa & N S Sukhadeva

Department of Textile Technology, Indian Institute of Technology, New Delhi 110 016, India

Received 29 September 2003; revised received and accepted 27 April 2004

A detailed analysis on the effect of fibre-to-fibre friction along with the carding parameters on the openness of fibre has been carried out. The fibre openness has been correlated with the drafting force of rovings and properties of sliver, roving and yarn. It is observed that the fibre-to-fibre friction has significant influence on the fibre openness. The increase in fibre openness results in decrease in roving drafting force . The nep count and short fibre content of card sliver, mass irregularity of card sliver, draw frame sliver, roving and yarn, total imperfections and yarn tenacity are significantly influenced by the fi bre openness.

Keywords: Cotton, Drafting force, Fibre friction, Fibre openness, Yarn imperfections IPC Code: Int. CI.7 DO 1 G9/00; D02G3/00

1 Introduction Various workers ' ·5 have devised methods of

measuring the openness of fibre and defined openness in different ways. However, very little information is available in the literature to indicate in what way the openness of fibres in blow room affects the ultimate quality of yarn and the processing behaviour up to spinning. The cotton fibre generally comes in the form of highly compressed bales, each bale consisting of a very large number of tightly packed layers of tufts of cotton and each tuft comprising hundreds of thousands of fibres. The fibres in the tuft are arranged in a random order. The tufts contain a large quantity of foreign matter, leaf and seed particles embedded between the fibres. It is the problem of the spinner to open out these tufts of cotton and eliminate trash as far as possible with least damage to fibre. It is important to remember that the opening action is not limited to the blow room only. Intensive opening takes place at the card where the cotton tufts are converted into almost individual fibres . In the earlier studies6•7, the effect of some blow room and card parameters on openness of cotton has been reported. Also, the openness at blow room and card stages has been correlated with the yarn quality.

The process of attenuation of linear fibre assemblies by roller drafting generates tension in the

"To whom all the correspondence should be addressed. Phone: 26591413 ; Fax: +91 -11-26851103; E-mail: apurba_das@ hotmail.com/apurba@ textile.iitd.ernet.in

fibres in the drafting zone. The average tension in the moving fibre mass in the drafting zone is referred to as the drafting force8. In addition to the different other parameters9•IO, fibre openness is an important parameter which affects the drafting force of slivers and rovings.

A very good openness of fibre tuft is achieved by separating fibres from each other. Apart from the mechanical means of separating the fibres, there are some fibre parameters which play an important role. The fibre-to-fibre friction is very important amongst these fibre parameters. The fibre-to-fibre coefficient of friction is an indication of clustering tendency of fibres. The higher the fibre-to-fibre friction, the higher will be the clustering among the fibres and thus more difficult the opening. The knowledge of the frictional values of individual fibres is very important to predict whether the processing will be satisfactory or not when the other physical properties are satisfactory. Hence, in addition to the adjustment of blow room and/or carding parameters, the proper selection of fibre-to-fibre frictional coefficient helps in achieving the optimum openness. In the present paper, the combined effect of fibre-to-fibre friction along with licker-in speed and cylinder-flat setting on cotton fibre openness has been reported. The impact of degree of opening on yarn quality has also been reported. An attempt has been made to correlate the degree of opening of fibre with the drafting force of roving to predict the quality of yarn.

ISHTIAQUE et at.: STUDY ON FIBRE OPENNESS 27

2 Materials and Methods The present study was carried out in a modern mill

using the same mixing (100% J-34), which the industry was using. The properties of grey cotton were: 2.5% span length, 26.8 mm; 50% span length, 13.3 mm; uniformity ratio, 49.6%; short fibre content, 10.25%; fibre fineness, 3.9 Ilg/in; and bundle strength, 21.63 g/tex.

The cotton was dyed in different shades with natural dyes to get different levels of frictional coefficients. The reason for using natural dyes is that these dyes are mainly surface deposition type, resulting in significant change in frictional properties of fibre with practically no effect on the tensile properties of fibres. The cotton was dyed with wide range of dyes. For linen colour dyed and blue colour dyed cottons, used in the present study along with grey cotton, it was found that there is no change in other properties except the frictional properties. The properties of grey and dyed cottons are given in Table 1.

No significant change in the properties of cotton, except the frictional coefficient, was observed after dyeing. The objective of the present study was neither to study the effect of cotton type nor the effect of natural dyeing. The natural dyed cotton was used just to change the fibre friction as one variable along with the other two variables, viz. licker-in speed and cylinder-to-flat setting. The cotton fibres with three different levels of coefficient of friction were then processed in a conventional blow room line with scutcher, keeping settings and speeds of all the beaters unchanged for all the samples. The laps thus produced were run through cards (C 1/3) where two card parameters (licker-in speed and cylinder-to-flat setting) were changed to vary the opening intensity and hence the degree Of opening of card web. The card sliver was then processed under similar conditions through breaker and finisher draw frames, speed frame and ring frame to produce 20s Ne yarns with 3.8 TM. A three-variable Box and Behnken design was used to investigate the influence of fibre-to-fibre friction and carding parameters on the degree of opening at card and the yarn characteristics. The actual and coded values of three variables are given in Table 2.

2.1 Fibre Testing

The grey and dyed cottons were tested for 2.5% span length, uniformity ratio and short fibre content in the Classifiber KCF/LS from Keisokki . Fibre bundle

Table I-Properties of grey and dyed cottons

Property Grey Linen dyed Royal dyed cotton cotton cotton

2.5% span length, mm 26.8 26.6 26.7

50% span length, mm 13.3 13.0 12.9

Uniformity ratio, % 49.6 48.9 48.3

ShOll fibre content,% 10.25 10.38 10.46

Fibre fineness, /-!g/inch 3.90 3.96 3.88

Bundle strength, g/tex 21.63 21.64 21.49

Fibre frictional coefficient, /-! 0.3 0.4 0.5

Table 2- Actual values of variables corresponding to coded levels

Variable

Fibre friction (XI) Licker-in speed (Xl)' rpm Cylinder-flat setting (X3), thou

-1

0.3 650 10

Coded ' level

o

0.4 850 13

+ 1

0.5 1050

16

strength and micronaire values were tested using Stelometer and airflow instrument respectively . The degree of opening of card web was measured using the procedure and equation as proposed by Ishtiaque

3 . . et at . An average of twenty readmgs was taken for. each sample. It should be noted that a lower value of. degree of opening indicates higher fibre openne~s;as indicated by the following relationship:

Coefficient of Coefficient of

compression recovery Degree of opening=----'-----=-----'.'---'--'--~-....L

Coefficient of compression

The frictional coefficients of the grey and dyed cotton samples were measured with the help of a friction tester!!. Three samples whose frictional coefficients were found to be equally spaced were selected for the study. These selected samples were grey, linen colour dyed and blue colour dyed with static frictional coefficients of 0.3, 0.4 and 0.5 respectively (Table 2).

2.2 Sliver and Roving Testing

The mass irregularities of card and finisher draw frame slivers and rovings were tested on Keisokki evenness tester. For testing of neps in card sliver, AFIS was used. The drafting force of roving was measured using a Draftometer!2, where the roving was fed in the drafting zone and the corresponding drafting force in terms of wattage was recorded through a dedicated PC attached to it. The test results of sliver and roving are given iriTable 3.

28 INDIAN J. FIBRE TEXT. RES., MARCH 2005

Table 3-Effect of fibre openness on sliver, roving and yarn properties

51. Variable Degree of Short Nep Card Draw Roving Roving Yarn Tota l Yarn

No. X, Xl X,l opening fibre count in sliver frame irregularity drafting irregularity imperfections/ tenacity of card content card sliver irregularity sliver U% force U% lOOOm g/tex sliver % neps/g U% irregularity W

U% 0.3 650 13 0.564 10.7 84 3.53 2.75 4.99 1.83 10.00 795 8.31

2 0.5 650 13 0.597 9.4 110 4.79 3.16 5.20 2.10 12.13 837 10.60 3 0.3 1050 13 0.547 11.4 91 4.36 3.38 5.56 1.83 1l.81 779 8.00 4 0.5 1050 13 0.589 9.5 98 4.02 3.13 4.98 2.10 10.52 876 11 .38 5 0.3 850 10 0 .548 11.1 95 4.52 2.93 5.33 1.85 11.85 765 9.05 6 0.5 850 10 0 .591 9.3 105 3.93 3.16 5.19 2.15 10.88 820 12.11 7 0.3 850 16 0.559 10.2 78 4.06 2.99 4.89 1.91 10.01 772 7 .55 8 0.5 850 16 0.593 9.1 115 4.70 3.00 5.33 2.10 12.19 843 11.l7 9 0.4 650 10 0.598 9.4 95 4.62 3.02 5.42 2.05 12.06 892 10.24 10 0.4 1050 10 0.566 9.7 75 3.67 2.54 4.76 1.92 10.80 769 11.43 11 0.4 650 16 0.588 9.1 98 3.82 2.94 5.12 1.95 10.63 880 11.66 12 0.4 1050 16 0.570 9.7 78 3.49 3.14 5.01 1.90 10.95 834 10.73 13 0.4 850 13 0.578 9.6 89 3.63 3.18 4.82 1.95 11.l2 869 1l.78 14 0.4 850 13 0.574 9.6 85 3.52 3.27 4.81 1.92 10.87 861 10.91 15 0.4 850 13 0.575 9.8 84 3.80 3.16 4.82 1.94 10.97 871 10.34

1.0 ;

/I!f ! t; , i .0 (b) (c)

.0

.' .= 0 i

0.5 i f / ; .i / '0 .,

'" Q tlI i j i C 0.0 f:)">/ 'l I ., / ./ /:' '" . I U .i I / :::;

.i / ·-0.5 .,!f' ..

.... / /' -' /

,/ .' .- " /,/ ,

-1.0 0.5 1.0 0.5 1.0 -0.5 0.0 0.5 1.0 -1.0 -0.5 0.0 - 1.0 -0.5 0.0

Fibre friction

Fig. I ~Effect of fibre friction and licker-in speed on degree of opening [cylinder-flat setting: (a) 10 thou, (b) 13 thou, and (c) 16 thou]

2.3 Yarn Testing Yarn irregularity and imperfections were tested on

Keisokki evenness tester with test speed of 400m/min and thin places, thick places and neps were measured at the levels of -50%, +50% and +200% respectively. Single yarn strength was measured using Uster Tensorapid. For measurement of yarn hairiness, Keisokki hairiness tester LASERS POT (Model LST) was used with test speed of 25m/min. The test results of yarn are given in Table 3.

3 Results and Discussion

3.1 Degree of Opening Table 3 and Fig. 1 show the influence of fibre

friction, licker-in speed and cylinder-flat setting on degree of opening of card web. The response surface equations for degree of opening of card web as a

function of the above parameters and the R2 values are given in Table 4. It is clear from Table 4 that there is a very good correlation between the degree of opening and the variables (fibre-to-fibre friction, licker-in speed and cylinder-flat setting) . The contour plots (Fig. 1) show that at lower fibre-to-fibre friction, the value of degree of opening is also low, which means that the fibre openness increases with the decrease in fibre friction (lower degree of opening means higher fibre openness) . This may be due to the fact that the fibre with lower coefficient of friction shows lower inter-fibre cohesion which results in easy separation between the fibres at the time of opening and cleaning. It is also clear from Fig. 1 and Table 3 that the fibre openness increases with the increase in licker-in speed, the effect being more in case of fibre with higher friction. As the licker-in speed increases, a more intensive beating takes place which results in

ISHTIAQUE et al.: STUDY ON FIBRE OPENNESS 29

Property

Table 4-Response surface equations for various yam characteristics

Response surface equation Coefficient of determination

R2

Degree of opening of card sliver

0.576+0.019Xj-0.009 X2+O.001Xr O.OO5 X/+0.003 X/+0.OO2 X/+0.OO2 X, X2+O.003 X2Xr O.002 X3Xj

0.967

Short fibre content 9.67-0.76Xj+0.21X2-0.17X3+0.52 X/-0.26X/-0.15Xj X2+O.17X3Xj 0.983

0.893

0.775 ·

Nep count in card sliver

Card sliver U%

Draw frame sliver U%

Roving U%

86.0+10.0X,-5 .62X2+10.75Xj2-X/+l.5X/-4.75X, X2+6.75X3Xj

3.65+. 12Xj-0. 15X2+0.46X/+0.J9X/-0.4X, X2+O.16X2X3 +0.31X3X,

3.20 -0.IX/-0.19X/ -.16X,X2+O.l7X2X3 0.692

0.639

0.956

0.933

0.667

0.893

Roving drafting force

YamU%

4.82+0.24X, 2+0. 13X/+0. 13 X/ +0.2XjX2+O. 14X2X3+O. 15X3X,

1.93+0.26X,-0.23X3+O. 13X,2+0. 12X/-0.85X,X2+O.39X2X3+O. 79X3Xj

10.99+0.26X,-0.23X3+O.13Xj 2+0. 12X/ -0.85Xj X2+O.39X2X3+O.79X3X,

Total imperfections

Yam tenacity

867+ 33.1X,-18.2X2+ 1O.4Xr44.5Xj 2-0.75X/-22.5X/ + 13.7Xj X2+ 19.2X2X3+4.0X3Xj

11.01+ 1.63X,-1.33X, 2-0.22X/ +0. 23X/ +0.38XjXr0.53X2X3+0.32X3Xj

12 ~-------------------------------, 120

";ft. 11

c' ~ 8 10 ~ "" t:: o J:; en 9

• Short fibre content

110 ~ Q.

~ 100 .....

c: ::J

8 90 Q.

~ .... 60 .~

iii "E cu

70 ()

• Nep count 8 L'-:"-'-__ ~ ____ .l.-__ -'-__ ---'L..-__ -L-__ ....J 60

0.54 0.55 0.56 0.57 0.58 0.59 0.60 0.61

Degree of opening

Fig. 2-Effect of degree of opening on short fibre content and nep count of card sliver

increase in openness7. As a lower opening force is required to separate out the fibres with lower frictional coefficient, the impact of licker-in speed is low in these fibres. On the other hand, the fibres with higher fibre-to-fibre friction require higher opening force to separate from each other and thus the higher licker-in speed generates the required opening force for the fibres with higher friction. It is evident from Fig. 1 that the openness is not significantly affected by cylinder-flat setting.

Fig. 2 shows that a reduction in degree of opening (i.e. increase in fibre openness) leads to increase in short fibre content in card sliver. This can be attributed to the higher fibre breakage caused by intensive opening action at card while attempting to increase the fibre openness. Fig. 2 also shows that the nep count first decreases and then increases with the increase in degree of opening. At lower level of fibre

2.2

2.1

(/)

'iii ~ 2 cD e .E g> 1.9 E ~ • 0 •

1.8

• •

•

• • o

• . .. . •

•

1.7 L_.-1.._-l __ ~_-..L __ ..L.-_-1...~--.....J

0.54 0.55 0.56 0.57 0.58 0.59 0.6 0.61

Degree of opening

Fig. 3-Correlation between degree of opening of card sliver and roving drafting force

openness (greater degree of opening), the nep count increases due to the clustering of fibres and in case of high fibre openness, the marginal increase in nep count is due to the harsh opening action in carding.

3.2 Drafting Force of Roving

Table 3 shows the effect of various parameters, affecting the openness of fibre, on the drafting force of roving. The response surface equation for roving drafting force (Table 4) shows a very good correlation (R

2 = 0.956) between these parameters (fibre friction,

licker-in speed and cylinder-to-flat setting) and roving drafting force. It can be seen from Fig. 3 that the degree of opening is well correlated with the drafting force of roving. With the increase in degree of opening (i.e. decrease iri openness of fibre), the

30 INDIAN 1. FIBRE TEXT. RES. , MARCH 2005

(e)

2.10 ....• ~ .. "

>-• " "

S 780 ~

o Yam U% " Total Imperfections

• rn 0.64 0.55 0.56 0.57 0.58 0.59 0.60 0.61

Degree of opening

Fig. 6-Effect of degree of opening on irregularity and total . , imperfections of yam

ISHTIAQUE et al.: STUDY ON FIBRE OPENNESS . 31

14 r---------------------------------,

12 • • • • •

•

• • 6 •

•

61--__ -J,... __ ---' __ -'-__ --" __ .J-._ .......... __ -'

0.54 0.55 0.56 0.57 0.56 0.59 0.60 0.61

Degree of opening

Fig. 7-Effect of degree of opening on tenacity of yarn

then increases. The reason for this has already been explained. The total imperfections decrease with the increase in fibre openness. This can be attributed to the better opening of fibres which results in uniform drafting of fibre strands. It is evident from Table 3 that the tenacity of yarn increases with the increase in coefficient of fibre friction from 0.3 to 0.5, keeping the other variables constant. The increase in tenacity, due to the increase in coefficient of fibre friction, ranges from 27.5% for lower licker-in speed to 42.2% for higher licker-in speed. Similarly, the increase in tenacity ranges from 33.8% for lower cylinder-flat setting to 47.9% for higher cylinder-flat setting. The tenacity of yarn (Fig. 7) increases initially as the fibre openness increases and then . decreases with further increase in openness. The initial increase in yarn tenacity with the increase in openness may be due to the proper alignment of fibres as a result of better drafting of more open fibres. However, further increase in fibre openness may be at the cost of fibre breakage, as explained earlier, which results in a drop in yarn tenacity.

4 Conclusions 4.1 The openness of card sliver increases with the

decrease in fibre-to-fibre friction. 4.2 Fibre openness increases with the increase in

licker-in speed; the effect is more in case of fibre with higher friction.

4.3 Openness is not significantly affected by cylinder-flat setting but shows a marginally decreasing trend as the cylinder-flat setting increases above a certain limit.

4.4 Drafting force of roving decreases with increase in fibre openness .

4.5 The nep count initially decreases sharply with the increase in fibre openness but at very high level of fibre openness it increases marginally. The short fibre content increases consistently with the increase in fibre openness.

4.6 The irregularities of card and draw frame slivers, roving and yarn decrease initially and then increase with the increase in fibre openness.

4.7 Total imperfections decrease consistently with the increase in fibre openness. The tenacity of yam increases initially as the fibre openness increases and then decreases with further increase in openness.

References 1 Bostock W, Freeman S M, Shorter S A & Williams T C, J

Text Inst, 46 (1955) Tl71. 2 Chellamani K P, Shanmughanandam D & Karthikeyan S,

Indian Text J, June (1988) 76. 3 Ishtiaque S M, Nishkam A & Tripathi Y, Design and

fabrication of openness tester, Proceedings, 40''' Joint Technological Conference of ATIRA, BTRA, SITRA and NITRA (SITRA, Coimbatore), 1999,25.

4 Bhaduri S N, Effect of openness of cotton on subsequent processing. Proceedings. Joint Technological Conference (ATIRA, Ahmedabad) 1959.

5 Rutkowskii J, Fibres Text Eastern ElIr, (1995) 39. 6 Ishtiaque S M, Das A & Chaudhuri S, Indian J Fibre Text

Res. 28 (2003) 399. 7 Ishtiaque S M, Das A & Chaudhuri S, Indian J Fibre Text

Res. 28 (2003) 405. 8 Dutta B, Salhotra K R & Qureshi A W, Blended Textiles

[The Textile Association (India), Mumbai] , 1981, 136. 9 Das A, Ishtiaque S M & Kumar Rajesh, Indian J Fibre Text

Res. 29 (2004) 173. 10 Das A, Ishtiaque S M & Kumar Rajesh, Indian J Fibre Text

Res. 29 (2004) 179. 11 Ishtiaque, S M, Das, A & Sharma. Y, Design and

Development of a Friction Tester for Measuring the Frictional Characteristics of Staple Fibres and Fabrics.

paper presented at the 43rd Joint Technological Conference

of ATIRA, BTRA, SITRA and NITRA, lIT Delhi , 2nd _3rd

March 2002. 12 Das A, Ishtiaque S M, Yadav P & Kumar Rajesh, Design and

development of draftometer and a critical study on drafting force of roving, paper presented at the 44th Joint Technological Conference of ATIRA, BTRA, SITRA and NITRA, South India Textile Research Association , Coimbatore. 8th - 9th March 2003.