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Indian Journal of Fibre & Textile Research Vol. 28. December 2003. pp. 399-404
Influence of fibre openness on processibility of cotton and yarn quality: Part I - Effect of blow room parameters
S M Ishtiaque & S Chaudhuri
Department of Textile Technology, Indi an Institute of Technology. New De lhi 110016, Indi a
a nd
A Das"
Northern Ind ia Textile Research Assoc iation, Sector-23 , Raj Nagar. Ghaziabad 20 I 002 , Indi a
Received 3 Jun e 2002; accepted 20 September 2002
The influence of fibre openness in the bl ow roo m on processibility of cotton and yarn quality has been studi ed . The change in the settings of beaters at three different stages o f blow room changes the openness of fibres . It is observed that the blow room cleaning efficiency changes with the openness of fibre and the manner in which opening takes place is also important. The changes in fibre openness at blow room do not appreciably influence the yarn inegul arity. With the increase in openness at blow room the yarn tenacity and total imperfections improve but at a very hi gh o penness. these parameters deteriorate sharply. The optimum degree of opening is found to be 0 .622, whi ch has been obtai ned through, the settings of 7 mm. 6 mm and 6 mm at porcupine, fine kirschner and scutcher kirschner beater respectively.
Keywords: Beater setting, Cotton, Fibre openness, Kirsch ner beater, Yarn imperfections. Yarn irregul arity
1 Introduction The raw material for the manufacture of cotton
yarn comes generally in the form of highly compressed bales of cotton. Each bale consists of a very large number of tightly packed layers of tufts of cotton and each tuft contains hundreds and thousands of fibres . The tufts contain, embedded between the fibres, a large quantity of foreign matter, leaf and seed particles. It is the problem for the spinner to open out these tufts of cotton, eliminate trash as far as possible and prepare an even strand of sliver and roving which can be efficiently subjected to the final drafting operation. The opening and cleaning at blow room, bes ides at card and draw frame, playa vital role in the preparation of a quality sliver which is essential for the production of good quality yarn. Blow room in general does not get its share of importance in the industry, particularly with reference to the extent of fibre opening it can achieve. Its influence on yarn has been underestimated. With the increasing demand on yarn quality and the ever-increasing deterioration In
"To whom all the correspondence shou ld be addressed . Present address: Department of Textile Technology. Indian Institute of Technology, New Delhi 11001 6, Indi a. Phone: 2659 14 13; Fax: 0091 -011-2685 1103; E-mail: apurba_das @hot mail.com/ apu rba@ textile.i itd .ernel.in
quality of cotton due to the presence of high amount of trash and other contaminants, it is necessary to pay attention to the degree of opening to be given to the cotton to provide the best quality product to the customer.
High degree of opening of fibres is essenti al fo r good quality yarn but how does thi s opening occur is also equally important. The yarn quality cannot be continuously enhanced with simultaneous increase in degree of opening, since the possible chances of over beating the fibres , and damaging and stressing them must also be avoided. This necess itates the consideration of both the positive and negative aspects of degree of opening and hence demands an optimum va lue of openness of fibres. For the purpose. it is necessary to measure the extent of opening achieved and then to observe the respec ti ve characteri stics of yarn.
Various workers ' ·6 have devised methods of measuring the openness of fibre and defin ed openness in different ways. However, very little is avai lable in the literature to indicate in what way the openness of fibres in blow room affec ts the ultimate quality of yarn and the processing behaviour up to spinning. In the present work, an attempt has been madc to study the influence of fibre openness in blow room on yarn
400 IND IAN J. FIBRE TEXT RES .. DECEMBER 2003
quality. The main objective of the study is to investigate the contribution of intensity of opening at blow room to the degree of opening of cotton fibre and to study the effect of fibre openness on yarn characteristics. The optimization of the degree of opening at bl ow room so as to achieve consistent quality product at optimum productivity level has also been done.
2 Materials and Methods
Medium grade 100% cotton mlxll1g (2.5% span length 26.8 mm, bundle strength 21.6 g/tex, micronaire 3.7, uniformity ratio 48.5 %, trash content 4.36(7'0 and short fibre content 10.07%) was used in the present study. The mi xing was then processed in a conventional blow room line consisting of a mixing bale ope ner with a porcupine bea ter, followed by step cleaner with fine kirschner beater and then scutcher with a kirschner beater. The settings in each of these openers were altered to vary the opening intensity and hence the fibre openness. The laps thus produced were then processed under similar conditions and machinery through card, breaker and finisher draw frames, speed frame and ring frame to produce yarn of a constant (30 Ne) fineness. A three-variable factorial des ign proposed by Box and Behnken (Table 1) was used to investigate the influence of blow room settings, hence the degree of opening at blow room stage, on the yarn characteristics. The ac tual values of three variables and their coded levels are given in Table 2.
2.1 Sample PI'eparation For a ltering fibre openness at blow room, the
sett ings of the beating element at three places in the blow room line were changed at three levels (Table 2). In mixing bale opener, the setting between the feed rolle rs and the porcupine beater was changed at 3 levels . The next machine was the step cleaner where the setting between feed rollers and a fi ne (s mall) kirschner beater was changed. The final machine was the scutcher where the setting between the pedal roller and the kirschner beater was changed at 3 leve ls . One lap was produced for each of the 15 combinations as shown in Table 1. Cotton fibres were collected at different intervals after scutcher kirschner bea ter to form a homogeneous sample for openness measurements. All these samples were placed very gently inside plastic packs with suffici ent air inside for minimal di sturbance to openness. Fifteen different types of yarns were prepared from these fifteen laps.
Table I _. Box and Behnken design for three factors at three leve ls
Experimental Variah le combination No. X Y Z
I -1 -l 0 2 - 1 + 1 0
3 +1 -I 0 4 +1 +1 0 5 -I 0 - I
6 -I 0 +1
7 +1 0 - I
8 +1 0 + 1
9 0 -I - I
10 0 -I + 1
II 0 + 1 - I
12 0 + i +1
13 0 0 0
14 0 0 0
15 0 0 0
Table 2-Actual values of variables and their c0ded level s
Variable Coded level
- I 0 + 1
Setting of porcupine beatcr (X). mm 6 7 8
Setting of fine kirschner beater (Y). Illm 6 7 8
Setting of scutcher kirschner beater (Z). mm 6 7 8
2.2 Testing 2.2.1 Fibre Testing
Raw cotton and fibre taken after the kirc shner beater of sc utcher were tested for 2.5 % span le ngt h. uniformity ratio and short fibre conte nt in the Classifiber KCFfLS from Keisokki . For the es timat ion of trash content, the trash analyser was used and fibre bundle strength was tes ted in Stelometer. The micronair values were obtained us ing airflow melhod . For testing of neps in card sliver, AFIS was used. NITRA openness tester was used to measure (he degree of opening of fibre taken after the kircshner beater of scutcher. The degree of opening was measured using simi lar formula as reported ear lier'. Fifteen tests were conducted for eac h samp le. Lower the value of degree of opening higher is the fibre openness.
Degree of opening = Coefficient of compression - Coeflic ient of recovery
Coefficient of compress ion
2.2.2 Yarn Testing Yarn irregularity and imperfections were tested in
Keisokki evenness tester with test speed of 4()()m/mi n
ISHTIAQUE el at. : INFLUENCE OF FIBRE OPENNESS ON PROCESSIBILITY OF COTTON -WI
and thin places, thick places and neps were measured at the levels of -50%, +50% and +200 % respectively. Single yam strength was measured using SOL Universal tensile tester. For the measurement of yam hairiness, Keisokki hairiness tester LASERSPOT model-LST was used with test speed of 25m/min.
3 Results and Discussion 3.1 Effect on Degree of Opening of Fibres
From the results given in Table 3 and the response equation shown in Table 4, it can be said that in general the openness increases with the decrease in settings of beating elements and that the correlation is very high with R2 value of 0.984. When the setting of porcupine beater is kept constant, the major job of openi ng is done by fine kirschner beater. For 6 mm setting of porcupine beater, openness increases with the decrease in fine kirschner beater setti ngs . The same is observed for 7 mm setting of porcupine where openness increases gradually with the decrease in fine kirschner settings, indicating that the material is suitable for further treatment by fine kirschner. For
Table 3 - Dcgree of opening in bl ow room with different beater settings
Experimental Beater settings, mm Degree of combination No. X Y Z opening"
I 6 6 7 0.600
2 6 8 7 0.618
3 8 6 7 0.744
4 8 8 7 0.890
5 6 7 6 0.617
6 6 7 8 0.622
7 8 7 6 0790
8 8 7 8 0. 850
9 7 6 6 0.622
10 7 6 8 0.637
II 7 8 6 0680
12 7 8 8 0703
13 7 7 7 0.650
14 7 7 7 0.652
15 7 7 7 0.649
"Lower value indicates better openness.
Table 4--Response surface equation for degree of opcning
Vari able Response surface equation R2
Degrec of ope ning at 0.65 1+0. 102X+0.036Y+ 0.984 scutcher kirschner 0.01 3Z+0.06IX2+O.OO8Z1
beater +0.032X Y +0.014Xl
wider porcupine setting, not much improvement in opening can be obtained probably due to Ihe insufficient initial openi ng. When the middle and last beating e lements, i.e. fine and scutcher kirschner. settings are kept constant, the change in degree of opening is mainly due to the change in porcupine beater settings . In this case too, for wider settings of fine kirschner, not much improvement in opening can be obtained by using even closest porcupine setting. Scutcher kirschner beater plays no major role in increasing openness , which indicates that it s importance lies in the making of well -textured laps.
3.2 Effect on Blow Room Cleaning Efficiency From Fig. 1 it is clear that the blow room cleaning
efficiency increases with the increase in fibre openness and after reaching to the maximum efficiency it drops sharply with further increase in openness. Thi s is evident that by making the materi al more open , the trash particles are better exposed and hence easi ly removed. Three distinct regions can be observed. A sharp rise in blow room cleaning efficiency is due to the marked increase in openness. fol lowed by an almost steady rise reaching to maximum and then ending with a sharp drop. The drop in blow room cleaning efficiency is probabl y due to the shattering and crushing of trash particle by employing very fine settings at initial stage, causing separation of trash difficult at later stages. Thus. not only degree of opening but also the manner in whi ch this opening is achieved is important.
3.3 Effect on 2.5 % Span Length Fig. 2 shows that the span length remains almost
unchanged with the increase in open ness but onl y up to a certain point, beyond which the span length
80
, 0 70 0 '
0>l) C Ql
' (3
~ 60 0> C 'c co Ql
U 50
40
0.600 0.661 0.722 0.783 0.844 0.905
Degree of opening in blow room
Fig. I- Effect of libre opcnness on blolV room cleaning clTicicncy
402 INDIAN 1. FIBRE TEXT. RES ., DECEM BER 2003
decreases with the further increase in fibre openness ending with a sharp decline in span length. This could be due to the over beating of the material by using very fine setting at the beginning of blow room line when the material was still in a compressed state, thus stress ing the fibres, shown as region A where the correlation is much highe r.
3.4 Effect on Short Fibre Content It can be seen from Fig. 3 that there is a very steady
ri se in short fibre content as the fibre openness is increased. This can be explained by the fact that the fibres are stressed under very intense opening, causing breakage of fibres and hence the increase in percentage of short fibres .
3.5 Effect on Card Sliver Quality
It is observed from Fig. 4 that the card sl i ver irregularity decreases gradually with the increase in openness at blow room, reaches a minimum and then increases sharply at high values of openness. More open the flocks , better they are prepared for carding ac ti on, i.e. the card can be better exploited for its function, resulting in uniform web and hence sliver. The rise in irregularity at higher openness may be due to the non-uniformity of openness. It is also ev ident from Fig. 5 that the nep count, i.e. number of neps per gram in card sliver, decreases with the increase in fibre openness at blow room but it increases sharply as the openness is very high . This may be due to the fact that with the reduction in unopened fibres, these cannot form nuclei for neps, But with the over beating than what is necessary, fibres are stressed and damaged which then buckle and tend to form neps.
E E r:
27
rn 26 c: ~ c: ro 0-(f)
~ 25 N
24 0.600 0.661 0.722 0.783 0.844 0.905
Degree of opening in blow room
Fig. 2-Effect of fibre openness in blow room on 2.5 % span length
3.6 Effect on Yarn Quality 3.6.1 Yarn Irregularity and Imperfections
Fig. 6 shows that the changes in fibre openness at blow room do not appreciably influence ya rn irregularity directly , as also reflected by very poor correlation, considering the draft in the subsequent stages of blow room. The contribution of a stage of processing to the yarn evenness depends on what the process does to the configuration of fibres so as to
15
"<f-
~ 14 C o u Q) .... .0 <;::
12 0.600 0.661 0.722 0.783 0 .844
Degree of opening in blow room
Fig. }--Effect of fibre openness on short fibre content
0.661 0.722 0.783 0.844
Degree of opening in blow room
0.905
0.905
Fig. 4--Effcct of fibre openness on card sli ver irregularity
130
120 OJ
. ~ 110 Q)
Co 100 C 6 90 t)
g- 80 Z
70
6861..:-0-=-0 _-0...J.6L6-1 --0...J.7'-22--0-. 7...JS-3--0...!..S-44--0. 905
Degree of opening in blow room
Fig. 5---Effect of fibre openness on nep coun t in card s li ver
ISHTIAQUE el al.: INFLUEi CE OF FIBRE OPEN lESS 0 PROC ESSIBILITY OF COTTON 4()J
substantially influence the behaviour of material during subsequent drafting. It is thus important to consider the manner in which changes in fibre configurati on caused by machinery from blow room to ri ng spinn ing can affect yarn evenness. The ri se in ya rn irregulari ty at higher blow room open ing can be explained on the basis of the fact that wi th the intense opening the short fibre percentage increases. Thi s poses problems during drafting and also causes uneven twist take up.
It is clear from Fig. 7 that with the increase in openness at blow room the total impelfections reduce but at very high openness it increases sharply. Higher the degree of opening, smaller is the tuft size and better the fibre separation, which is conductive to good drafting. A more opened material with lesser variations in tuft propel1ies can be processed better than an insuffici ently opened material and this results in fewer imperfections. But the increase in total imperfections again after an optimum openness at blow room could be explained in accordance with the behaviour observed in case of nep count in card sliver.
170 ,------------------------------------,
oe. ::::l 165
:( I
J 160 ~ V
15.5 L . ______ -L ______ ...l...-______ IL-____ --.J
0.600 0.661 0.722 0.783 0.844
Degree of opening in blow room
Fig. 6--Effect of fibre openness on yarn irregu larity
1000
E .x:
~ 900 o n ~ Q) c.
.~ 800
ro ;§
700 0.600 0.661 0.722 0.783 0844
Degree of opening in blow room
0.905
0.905
Fig. 7-Effecl or fibre openness on total imperfections of yarn
3.6.2 Single Yarn Strength Fig. 8 shows that the yarn tenacity improves wit h
the increase in openness of fibres at blow roo lll although the correlat ion is not very hi gh (-0.696 ). Thi s may be due to the fact that with more fibre opening the fibre movement during draft ing is more controlled than that when they are not suffici entl y opened. Better fibre cont rol res ults in uni form materi al that facilitates proper fibre orientati on during spinning, contributing to yarn strength . Thi s cont in ues until a stage is reached where opening is overd one and over stress ing the fibres creates more fibre damage, thereby bringing down the single yarn strength drastica lly.
3.(i.3 Yarn Hairiness The yarn hairiness (Fig. 9) remains almost
unchanged initially with the increase in openness at blow room but at higher level of openness it increases sharply. This is attributed to the over stress ing or fibres at hi gh values of openness with slC:lp le shortening and generation of short fibres. The resulting short fibres could be the cause of increase in
13 ,---------------------------------~
x 2 12 OJ Z:-u C1l c 2 E 11 ~
11-~--l1-~-L--....--J 0.600 0.661 0.722 0.783 0.844 0.905
Degree of opening in blow room Fig. 8-Effect of fibre openness on yarn tenaci ty
180
« 160 I u; ::J
~ 140 f-en en OJ c
:~ 120 f-
I
100 0.600 0.66 1 0.722 0.783 0.844 0.905
Degree of opening in blow room .
Fig. 9--Effect of fihre openness on hairiness of yarn
404 IND IAN J. FIBR E TEXT. RES., DECEMBER 2003
ha iriness as the f ibres are never bo und within the yarn body and as suc h they cannot take up tw ist uniformly but are expe lled to the surface w ith the ir ends protruding as ha irs .
4 Conclusions ·U W ith the decrease in setting of beati ng e lements the openness inc reases and the f irst opening e lement plays a maj or ro le, i.e, w ith insuffi c ient in itia l opening not much improvement in ope ning can be ac hieved even with fin e r sett ings o f o the r bea te rs . 4.2 B low room cleaning effic iency inc reases w ith the inc rease in opening but fa ll s a fte r a certa in value of openness. F ine settings at initia l beating po int can shatte r trash particles, mak ing the ir re mova l di ffic ul t at later stages. T hus, the manne r in w hich the opening takes place is a lso important. 4.3 2.5 % span length of cotto n remains unchanged over most va lues of ope nness but de teriora tes unde r very intense opening when f ibres are stressed . Sho rt fib re content increases stead ily w ith the inc rease in openness . 4.4 Card s li ver irregul arity decreases g radua ll y with the increase in openness at blow room, reaches a min imum and then inc reases sharp ly a t high va lues of openness. T he nep count in card s li ver decreases wi th the inc rease in open ness a t bl ow room but it inc reases sharp ly when the openness is very high.
4.5 T he changes in f ibre openness at blow room do not apprec iab ly inf lue nce the ya rn irreg ul arity. With the increase in openness at blow room the to tal imperfect ions reduce but at very hig h o penness it inc reases sharply. 4.6 Yarn tenaci ty, in genera l, impro ves w ith the inc rease in openness of f ibres at blow roo m. Hairiness of ya rn remai ns a lmost unc hanged in iti a ll y wi th the increase in openness at bl ow room but at hi gher leve l of openness it increases sharp ly. 4.7 From a ll the observa ti ons and plots shovvn. the mos t optimum region fo r a ll characte ri st ics has bee n fo und to be that correspo nding to the ope nness va lue of 0 .622, which can be obta ined th ro ugh setti ngs o f 7mm, 6 mm, 6 mm a t porc up ine, f ine kirsc hner and sc utcher kirschne r beate r respecti ve ly.
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11151, 46 ( 1955) T I71. 2 Chcll amani K P. Shanmughanandam D & Kanhikcyan S.
Illdiall Texl J. June ( 1988)76. 3 Ishtiaq ue S M. Ni shkam A & Tripathi V. Design and
fabrication of openness tester. Proceedillgs, 40,h Joi ll l Techllological COllj('t'('I/ ce oj A TINA , BTRA , SITNA and ' ITN/I (SITRA. Coimhalore) , 1999.25.
4 Bhadu ri S N. Effect of openness of collon on subsequcnt processing, Proceedillgs, Joill l Techllological Conjercllcc (II' AT/RA, IJTRA alld SITRA (ATIRA . Ahmedabad). 1959 .
5 Rutkowskii J, Fibres Texl Easfem EliI', ( 1995) 39.
