-------------- -------------------~-:------Indian Journal of Fibre& Textile ResearchVol. 16, June 1991, pp. 133-136

Performance of man-made fibres in rotor spinning system

S Karthikeyan, P Chellamani& K GnanasekarSouth India Textile Research Association, Coimbatore Ml 014, India

Received 18 April 1990; accepted 21 September 1990

A comprehensivestudyto assessthe suitabilityof rotor spinningsystemforman-madefibres(MMF) andtheir blends has been carried out.OE yarns from MMF have been found 30-35% weaker than their ringcounterparts. Whiletheevennessisbetter for MMF rotor-spun yarns, the various imperfectionsare also lessin MMF yarns by 15-20%.

Keywords:Doublings, Drafting waves, Man-made fibres, Open-end yarn, Ring-spun yarn

"2.5% Span length, mm; and bMicronaire value, ~gjin

PolyesterViscoseCotton

Length, mm

383835"Denier

1.41.53.2b

Stelo strength at

421419

3 mm gauge, gjtex Maturity coefficient

-0.78Elongation,%

251712

2 Materials and MethodsPolyester, viscose, polyester/viscose and

polyester/cotton fibres/blends were used for thestudy. The properties ofthe fibres used are given inTable 1.

15sand 20s yams were produced from all the fourvarieties on a Lakshmi-Rieter Ml/2 OE SpinningMachine (24 rotors). Equivalent yam samples werealso spun from ring spinning for comparison. The

Kirschner3 has reported studies using wool,polyester and acrylic on BD 200 OE machines (withrotor speed of 35,000 rpm) to assess the influence offibre length on tensile and evenness properties ofrotor-spun yams.

However, not much information is available withregard to properties of rotor-spun yams at higherrotor speeds. The present project has, therefore, beenundertaken to assess the technical viability of rotorspinning for popular man-made fibres and theirblends at a higher rotor speed of 50,000 rpm.

Table I-Properties of fibres usedFibreProperty

1 IntroductionOnly a few innovations have aroused as much

interest as rotor spinning in India in the recent past.More than 55,000 rotors have been installed in Indianmills so fai". As per a joint study conducted byATIRA, BTRA & SITRA in 1985 for virgin cottonand waste mixings, little difference existed betweendifferent makes of rotors in yarn quality, though thestrength differed somewhat. However, there is verylittle published information with regard to thesuitability of rotor spinning technology forman-made _fibres(MMF) from the point of view ofyarn and fabric quality.

Almost 100% of the man-made fibres and blendsare being spun on the conventional ring spinningsystem in India as on today. The consumption ofman-made fibres/filaments has increased rapidlysince early 1960 and reached a level of about 13% inthe total consumption. As per the future projectionsmade, this will occupy a share of about 35% in 2000A.D. Therefore, it was felt that a comprehensivestudy to assess the suitability of rotor spinningtechnology for popular man-made fibres and blendswill be of great help to the user industry which isalready geared to go in for this technology in a bigway. Some studies on the properties of rotor-spunMMF yarns have been reported in the literature. Thestudy by Kaushiketal.2gives an account of the.contribution of twist to the breaking strength,extension at break and association between twist loss

and yarn evenness in acrylic-viscose rotor-spunyams. But this study has been confined to only 40,000rpm rotor speed.

133

INDIAN J.FIBRE TEXT. RES., JUNE 1991

:-50:"+50:200%

Table 2-Yarn samples produced

Parameter Yam

case ofOE yarns made from 100% cotton fibres, thedeficiency in strength was reported1 to be only15-20%. Also, the improvement in evenness of OEyarns (as compared to ring yarns) from man-madefibres was only about 1.3-1.5U% as against 3-4 U% inthe case of OE yarns from cotton. The relativelyhigher reduction in the strength and lowerimprovement in evenness of OE yarns fromman-made fibres are due to the following reason:

Ring-spun

100% Polyester100% Viscose

Polyester (Viscose(48/52)

Polyester/Cotton(67/33)

15s and 20s8

Rotor-spun

100% Polyester100% Viscose

Polyester/Viscose(48/52)

Polyester/Cotton(67/33)

l5s and 20s8

Fibre/blend

Counts spunTotal no. of

spinnings

details of yarn samples produced are given in Table2.

The process parameters adopted for ring and OEspinning are given in Tables 3 and 4 respectively. Theyarn samples produced were conditioned under thestandard atmospheric conditions (65% RH and80F) and tested for the following properties:

(i) Single yarn tenacity by Uster tensorapid.(ii) Count and strength variations.(iii) Unevenness (U%) and imperfections by

Uster II Evenness Tester at the following sensitivitylevels:

Thin placesThick placesNeps

3 Results and Discussion3.1 Properties of Polyester and Viscose Yarns

The properties of 15s0E and ring yarns spun frompolyester and viscose fibres are given in Table 5. It isobserved that OE yarns from man-made fibres areweaker than their ring counterparts by 30-35%. In the

Table 3-Process parameters adopted in ring spinning

Parameter

Yam type

P

VP(VPIC- 15s 20s15s20s15s20s15s20sSpindle speed, rpm

1120012500112001250012300125001280012500

TPI

13.915.7813.915.7814.315.7814.816.0

Roving hank

0.90.90.90.90.90.90.90.9

Finisher drawing

0.140.140.140.140.140.140.140.14

sliver hank

P-Polyester; V-Viscose; P(V-Polyester(Viscose; and P/C-Polyester/Cotton

ParameterTable 4-Process parameters adopted in OE spinning

Yam type

15s 20s

PVP(VPICPVP/VPIC

Rotor speed (x 1000 rpm)

5050505050505050

Combing roller speed ( x 1000 rpm)

66666666TPI

15.215.616.116.216.316.617.117.3Draft

103103103103125125125125

Separator angle, deg

4545454545454545

Type of doffing tubeRIORIORIORIORIORIORIORIO

Rotor diam, mm5454545454545454

134, !II"

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KARTHIKEY AN et al.:PERFORMANCE OF MAN-MADE FIBRES IN SPINNING

In the case ofOE spinning of cotton, drafting wavesdue to floating fibres in the drafting zones (which arecharacteristic features of ring spinning) are avoideddue to the elimination of 2nd passage draw frame, flyframe and ring frame. However, in the case ofman-made fibres, because oftheir uniform length, theproblem ('ffloating fibres during ring spinning is less.This means that the beneficial effect ofOE spinning inavoiding the drafting waves will be rather low whilespinning man-made fibres.

OE yarns from man-made fibres show 15-20% lessimperfections than ring yarns. The reduction inimperfections in the case ofOE yarns is.ascribed to thehigher number of doublings. The number ofdoublings in rotor spinning machine is given by1tD x TPI (where D i!\rotor diameter in inches andTPI, the turns per inch).

However, the reduction in imperfections is low ascompared to that in the case ofOE yarns from cottonfibres. As per the studies conducted by Seshanetai.1,the various yarn imperfections in OE yarns fromcotton mixing are lower by about 65%. The relativelylow reduction in imperfections in OE-spun MMFyarns is due to the reduction in the beneficial effect ofOE spinning in avoiding the drafting waves whiledealing with man-made fibres of uniform cut~length.

The count variations for OE yarns from man-madefibres are lower than that for ring yarns. The lowercountev in rotor yarns is due to the absence of stretchduring processing (especially at speed frames). The

slippage of material under the drafting rollers, whichis a source of countev in ring spinning, is also notoperating in rotor spinning.

3.2 i>roperties of Blended Yarns

The properties of 15sring and OE yarn~ spun frompolyester/viscose and polyester/cotton blends aregiven in Table 5. It is observed that the strengthdeficiency between OE and ring yarns does notimprove much by adding viscose or cotton withpolyester. As in the case of 100% polyester and I()()%viscose,0E yarns from P/V and P/eare also weakerthan their ring counterparts by 30-35%. Addition ofcotton to polyester reduces the tenacity of 100%polyester yarns by 10-12% with no significantdeterioration in evenness and imperfections.Addition of viscose to polyester reduces the strengthof 100% polyeste-yarns significantly. The strength ofpolyester/viscose (48/52) yarn is lower than that of100% polyester yarn by 40-42%. This is because ofthe poor load sharing properties of the componentfibres4

OE yarns from polyester blends show betterevenness (0.6 U%) and fewer imperfections (20-30%)due to the improved doublings and lower countevdue to the avoidance of stretch.

3.3 Effect of Yarn Count on the Properties of OE and Ring Yams

The properties of20s OE and ring yarns spun from100% man-made fibres and their blends are given in

Property

R.Km, gttexEvenness, U%

Imperfections/km

Thin places

Thick places

Neps

CV of count,%

R.km. g/tex

Evenness, Uo;.,Imperfections/km

Thin places

Thick places

NepsCV of count, %

Table 5-Properties of OE and ring yarns

Yarn typePolyester

ViscosePolyester/viscosePolyester/cotton

OE

RingOERingOERingOERing

155 COWIt 19.0

28:09.314.010.616.017.025.0

10.8

12.111.\12.610.611.211.011.6

4

9814688II24

24.293424282631

36

41344141524162

1.9

2.42.02.62.12.82.83.2

ZOsc...t 24.028.09.011.014.017.022.025.0

11.4

12.411.212.611.612.111.612.1

II

18131414162116

32

41343931364442

59

68626959S96971

2.1

2.81.92.92.12.42.33.0

135

INDIAN J.FIBRE TEXT. RES., JUNE 1991

Table 5. It is observed that as the count is increased

from 15s to 20s the breaking tenacity of OE yarnsfrom 100% polyester, polyester/viscose andpolyester/cotton improves, the improvement being26, 34 and 29% respectively. However, for 100%viscose fibres, the tenacity of OE yarns reducesmarginally (3%) as the count is increased from 15sto20s. In the case of ring yarns, as the count is increasedfrom 15sto 20s, the breaking tenacity remains more orless constant for polyester and its blends andmarginally reduces in the case of viscose.

Generally, one would expect a decrease in tenacityfor greater counts when yarns of different counts arespun from the same fibres. However, because of thesmall range of counts (l5s-20s) covered in this study,the tenacity could be expected to be more or less samefor both the counts. But the tenacity improved in thecase of polyester and its blends with increase in countfrom 15s to 20s. This may be due to the followingreasons:

The combing roller speed used was same (6000rpm) for both the counts but the drafts were about 107for 15s and about 142 for 20s. The opening rollerspeed being same and the total draft used in the case of15s being lower than that for 20s, such a situationwould result in lower degree of separation of fibres bythe opening roller in the case of 15scount. This may bethe reason for the reduction in tenacity of 15sOE yarnas compared to 20s.

However, further trials, covering a wider range ofcounts and fibres (polyester fibres from differentmanufacturers), are required to confirm this trend .

The yarn evenness does not seem to get affectedwith increase in count from 15sto 20s both in OE andring spinning for all the fibres/blends studied. Forunit increase in count, the yarn imperfectionsincrease by 5-15% for the counts and raw materialcovered in this study. The increase in imperfectionsdue to increase in count is found to be relatively higherfor OE yarns. This may be due to the fact that atgreater counts, the wrapper fibre effect is morepronounced in rotor-spun yarns (in OE yarns,wrapper fibres also get counted as neps). It is alsointeresting to note that the increase in imperfection

136

level with increase in count is mainly because of theincrease in neps. Count variation (count CV) does notincrease significantly with count.

4 Conclusions4.1 OE yarns from polyester and viscose fibres and

their blends are weaker than their ring counterpartsby 30-35% in 15scount and 12-18% in 20scount. OEyarns are more even by 0.5-1.5 U% with fewerimperfections (6-26%) as compared to ring yarns.The higher strength deficiency and relatively lowerimprovement in evenness of OE yarns fromman-made fibres are due to the reduction in the

beneficial effect ofOE spinning in avoiding draftingwaves while spinning man-made fibres.

4.2 Count variation is lower for OE yarns fromman-made fibres by 0.3-1.0% (absolute values). Theimprovement in count variation is ascribed to theavoidance of stretch and slippage of material underthe drafting rollers.

4.3 The breaking tenacity of OE yarns frompolyester and its blends improves when the count isincreased from 15s to 20s whereas that of ring yarnsremains constant. While spinning viscose yarns inring and OE systems, the tenacity decreasesmarginally as the count becomes greater. For a unitincreae in count, the yarn imperfections increase byabout 10% for the counts and raw materials coveredin this study.

AcknowledgementThe authors are thankful to Mr. T.V. Ratnam,

Director, SITRA, for guidance and valuable.mggestions during the study.

References1 Seshan K N, Chellamani P, Pillay K P R, Khurana S K, Mittal R

M, Sood M C, Balasubramanian N& Desai A N,Proceedings.26thjoint technological conf"erenceof"A TI RA. BTRA. SITRA&NITRA (Ahmedabad Textile Industry's Research Association,Ahmedabad), 1985, RPI-RP6.

2 Kaushik ReD, Salhotra K R&Tyagi G K,IndianJ Text Res. 12(1987) 139.

3 Kirschner,Melliand Textilher.53 (1972) 487.4 Pillay K P R,Proceedings. seminar on open-end spinning system

(South India Textile Research Association, Coimbatore), 1986,53-76.

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