Indian Journal of Fibre & Textile ResearchVol. 20, June 1995, pp. 92-96

Studies on spectrum density analysis of yam hairiness variations

A V Ukidve, V G Munshi, P K Mandhyan & G ViswanathanCentral Institute for Research on Cotton Technology, Matunga, Bombay 400 019, India

Received 7 March 1994; accepted 27 May 1994

An attempt has been made to extend the application of spectrum analyser to the textile field forthe first time for tracing the yam hairiness spectrogram from the output signals of Shirley hairinessmeter, using 11 yam samples widely differing in hairiness characteristics. The ~p_litude and wave-length of the hairiness periodicities would be useful for analyzing the causes of hairiness formationfrom the point of view of producing quality yams.

Keywords: Hairiness periodicity, Spectrum density analysis,Yam hairiness

1 IntroductionHairiness is an important element of yarn qual-

ity and its study is becoming all the more vital onthe practical mill floor level in view of the grow-ing popularity of synthetic/cotton blended yarn.Hairs are formed on the surface of yarn duringthe processing due to different reasons 1 such asrubbing during the ring rail movement, partialworn-out travellers, etc. The number and lengthof hairs protruding out due to each of the causesare not identical but vary widely. In addition,even in the case of single fault, the number ofhairs formed per unit length of yarn is not con-stant throughout the length of the full bobbin- Ithas been observed? to vary significantly from por-tion to portion even within a bobbin. Hairs ar.eformed with definite periodicity and cyclic varia-tion along the yarn length due to defects in themechanical processing. The amplitude and wave-length of the hairiness periodicities caused byeach of these defects are different and overlap oneach other. Thus, yarn hairiness variation spec-trum is the resultant of a number of superim-posed waves, varying in amplitude and wave-length.

Shirley hairiness meter+':' (SHM) is being in-creasingly used in Indian textile industry for quickevaluation of yarn hairiness (hairs/l00 m) withadditional advantage of being very simple and re-quiring little operator skill. Though a provisionexists in SHM for instantaneous recording of var-iation along the length of yarn, no facility is avail-able to obtain the spectrograph of hairiness. Aneed was, therefore, felt to make an arrangementto plot the spectrograph, keeping at the same time

the advantages of SHM. Although some attemptshave been made-" to plot hairiness variationspectrum using Uster evenness tester with hairi-ness module (Model UT-3), they appear to be ofpreliminary nature. In the present study, an at-tempt has been made to adopt a versatile elec-tronic instrument for computing the yarn hairinessspectrum from the signal output of SHM. Theelectronic instrument, called Rockland Mini Ana-lyser? (Model 5815A) is extensively used for anal-yzing oscillations due to mechanical vibrationsand noises. It has wide applications in aeronauti-cal, naval and acoustic studies.

2 Materials and Methods2.1 Yarn Samples

Eleven yarn samples, widely differing in hairi-ness characteristics, were selected from the lot ofseveral samples routinely tested over a period inthis Institute. These included a singed, smoothyarn with practically no protruding hairs, partiallysinged yarns, and yarns with multiple complex pe-riodicities.

2.2 TestsThe samples were tested for hairiness on SHM.

The standard method of counting only the hairslonger than 3 mm on SHM was considered notsufficiently precise for this work, as it does nottake into consideration the shorter hairs. There-fore, the adjustable disc of SHM was suitablyfixed to count the number of hairs longer thaneven 1 mm. It may be noted that in Model UT-3also, hairs longer than 1 mm are taken into ac-count in the evaluation of yarn hairiness to enable

UKIDVE et 01.: YARN HAIRINESS VARIATIONS

inclusion of all types of variation. Fifty observ-ations of 1 min duration were made on each sam-ple with a yarn speed of 60 yards/min and themean number of hairs (1 mm and longer) per100 mof yarn (SHM Index) was noted.

The electrical signal of 'SHM was suitablytapped and fed to spectrum analyser (SA). Afterseveral trials, the optimum settings on SA wereselected to synchronize it with SHM8; the detailsof experimental work are proposed to be given ina separate article. A brief summary of settings se-lected is given in Appendix 1.

SA normally provides access to 1024 points re-corded along the length of yarn (with option toextend to 10240 points) of time information fordisplay and computation. The visual display of In-stant Time (IT) shows the first 400 points out ofthe 1024 points of time samples transformed. Asthis display was found to be too much congesteddue to the dense nature of variations, the optionto display IT for only 80 seconds of yarn wasused.

In addition to 400 channels, SA has the advan-tage of combining variations occurring at higheras well as lower frequencies. The Third Octave(TO) spectrum depicted on SA represents a largerange of frequencies and covers almost all typesof variation in yarn hairiness. SA signal outputwas assigned voltage for Engineering Unit (EU)Constant enabling SA to convert the measuredvoltage into appropriate amplitude. It was con-firmed that the assigning of EU in SA resulted inthe computation of the magnitude of CV % on alevel with UT-3 tester. On exercising the optionof Third Octave (TO), the hairiness spectrogramis displayed on the monitor. It may be pointedout that taking advantage of options available onSA, the height of TO spectrograms can be adjust-ed to any desired level by selection of the suitableamplification in the range of 0.1-141 EU-RMS.Amplifications of 1.10 and 8.84 were set forplotting the standardized TO diagrams of. singedand partially singed yarns respectively so that theheights of the lower singed yarn and the higherpartially singed yarn spectra appear approximatelyequal to cope up with the following two prob-lerns": (i) The peak of periodic variation drawn ina low spectrogram seemed to be smaller than thatdrawn in the higher spectrogram, though the am-plitude of both was the same; and (ii) There was apossibility that a considerably low or a high spec-trogram will result, making the interpretation dif-ficult. Variations in yarn hairiness only due to ran-dom occurrence of fibres during processing is de-

93

picted as general hump in spectrograph. Thepresence of deviation(s) from normal shape orpeaks will indicate the need for corrective action.The wavelength and the amplitude of the hairi-ness periodicity were read from the band andheight of peaks. The overall pwer contained inthe bands on the display, which corresponds toCV'/o, was also read directly on the monitor. It isinteresting to note that the computation of CV'/oof hairiness by SA is similar to theoretical (statis-tical) calculation of yarn evenness CV'/o from thespectrograph 10 obtained from Uster evenness tes-ter. This confirms the accuracy of the displayedCV'/o results. Standardization of the SA settingshaving been completed, it was considered neces-sary to study and classify the different types ofhairiness periodicity that one may come across inthe yarns produced by the local mills for studyingthe adaptability of spectrum analyser.

3 Results and Discussion3.1 Adaptation

Table 1 shows the hairiness characteristics ofyarn samples selected for the study. Instant Time(IT), and Third Octave (TO) plots were taken onSHM-SA combination. In view of the voluminousnature of plots, only 12 selected plots, with thehairiness of predominant nature, are presented inFigs 1-12. The selected plots belong to followingfour yarns having diversified hairiness attributes.

• Less hairy yarn (singed yarn)• Ring (RF) and open-end (OE)

spun yarns• Yarns with one predominant

periodicity• Yarns with complex pattern

3.1.1 Less Hairy Yam (Singed Yam)Figs 1-4 show the IT and TO hairiness patterns

of a optimum singed and a partially singed yarn.Fig. 1 depicts almost straight line nature of IT ofyarn run for 80 seconds on account of elimina-tion of hairs due to singing. Fig. 2 shows a spec-trogram with no prominant peak for the identicalreason since the question of perodicities of hairi-ness does not arise in the case of singed yams.Compared to Fig. 1, the Fig. 3 shows the pres-ence of some hairs as the corresponding yam wasonly partially singed. This difference in the ITs isalso reflected in the respective TO plots (Figs 2and 4).

3.1.2 Ring and Open-end Spun YamsFigs 5-8 show the IT and TO hairiness features

of ring and open-end yams spun to an identical

94 INDIAN J. FIBRE TEXT. ~S., JUNE 1995

Table l=-Hairiness characteristics of the selected yarnsID Count Type of yarn SHM CV% Hairiness periodicityNo. index

Wavelength Amplitude(em) (EU)

7777 40s Singed 56 2.5 A A

8888 40s Partially singed 1765 16.0 A A7193 32s Ring-spun 7224 24.5 9.0 7.37493 32s Corresponding OE 5230 23.9 A A3198 30s Sinusoidal periodicity 13277 56.1 290 45.0

PIC 145 14.66584 80s Superfine RF yarn 5294 22.3 30 13.56539 50s Long-term periodicity 6483 26.2 458 6.4

366 6.56550 60s Fine RF yarn 5166 24.1 37 6.52117 40s Highly hairy 11064 35.1 366 12.4

5446 40s Multiple periodicity 8135 29.2 458 12.6RF 56 7.9

4 4.61055 32s Long-term periodicity 10241 32.3 458 17.8

A- Periodic wave absent

200.E+0 EU O-P

10,_'0~0~0~0~~~~~llS_ELC~O~N~O~SL-~~~-u.u.~8,0..l..~'0,.llLOO,~~,_I\. ':" ••I •••• " .""" •• "' I ~_L....----I._--'-_--'-_--L._-'--_-'--_-'-_-'-_-'-_ - 6 - 3 0"3 6 9 12 '5 '8 21

Fig. I-Instant time trace of 405 singed yarn

20 O.E+0 EU 0 - P0'0000 SECONOS 80 '000E:~!~::-:bb!:~

Fig. 3-Instant time trace of 40s partially singed yarn

200.E+0 EU O-P

Fig. 5-lnstant time trace of 32s RF yarn spun from170-C02

count of 32s from the same cotton variety, 170-C02. It is observed from Table 1 that OE yarnh'\~ less hairiness and lower variation than thecorresponding RF yarn. RF yarn has comparat-ively higher long-term periodicities as may be

Fig. 2- Third octave trace of 40s singed yarn

8 '84 EU RMSgr:;:]- 6 -3 0 3 6 9 12 15 18 21

Fig. 4- Third octave trace of 40s partially singed yarn

8'84 EU RMS

~' d'IJl-~~_,"·l~_.L-.-,-...., ..I I I I _

- 6 - 3 0 3 6 9 12 15 '8 21

Fig. 6- Third octave trace of 32s RF yarn spun from170-C02

seen in the higher hump (at 600 em wave length)in Figs 6 and 8. The lower hairiness of OE yarnmay be attributed to the presence of wrapper fi-bres and better control of short fibres during pro-cessing compared to that in RF spinning.

UKIDVE et al: YARN HAIRINESS VARIATIONS

200.E+O EU o-p'0-0000 SECONOS"O~

~~Fig. 7-Instant time trace of 32s OE yarn spun from

170-C02

20 O.E+ 0 EU 0 - p

~~Fig. 9-lnstant time trace of 30s P/ C RF yarn with sinusoidal

periodicity

200E+O EU O-P

~Fig. II-Instant time trace of 40s RF yarn with multiple

periodicities

3.1.3 Yarns with One Predominant PeriodicityFigs l) and 10 depict the IT and TO hairiness

characteristics of a yarn with a prominent sinu-soidal periodicity of 45.0 amplitude at - 5 band.It is interesting to note from IT diagram (Fig. 9)that the number of hairs per yard varies fromzero to a maximum of 200 in a cyclic manneralong the length of yarn, resulting in high CV %of 56.1 (Table 1). With the knowledge of thewavelength (290 em), the fault in the processingcan be located by taking into account the draft,front roller speed, ring diameter, ring rail lift, etc.In the present case, from the data of 290 cmwavelength, the periodicity of yarn hairiness canbe traced to the differences in the yarn tensionoccurring due to the upward and downwardmovements of the ring rail.

3.1.4 Yarn with Complex Hairiness PatternFigs 11 and 12 show the IT and TO diagrams

of 40s RF yarn with complex hairiness pat-tern due to multiplicity of causes in the process-ing machinery. Fig. 12 clearly indicates periodici-ties of short term (4 em), medium term (56 cm)and long term (458 cm) nature.

3.1.5 Comparison with Similar InstrumentsAn attempt was also made to compare the SA

hairiness spectrograph with that of UT-3 Model.

95

8·84 EU RM<::'

b2tS;J-& -3 0 3 6 9 12 15 1~ 21

Fig. R- Third octave trace of 32s OE yarn spun from170-C02

35·4 EU RMS

g~~~~".,.-1-6-3036912151821

Fig. 10- Third octave trace of 30s PIC RF yarn withsinusoidal periodicity

-'6-3 a 36912151821

Fig. 12- Third octave trace of 40s RF yarn with multipleperiodicities

Though both the equipment gave similar para-meters, such as hairs per unit length, CV'/o of hai-riness, and wavelength and amplitude of periodi-city, SA is provided with additional facilities suchas on-line measurement and display of the level ofamplitude: and storage of instantaneous hairinessvariation of yarns passed for 400 seconds formeasuring individual readings over short lengthsegments of yarns.

4 ConclusionThe application of spectrum analyser can be

extended to the textile field to locate the wave-length(s) and amplitude(s) of periodic variationls),if any, in yarn hairiness to .achieve better yarnquality demanded by modern high speed looms.

AcknowledgementThe authors are thankful to Shri S J Bhaka,

Electronic Engineer, for rendering technical as-sistance in tapping of signals.

References1 Dakin G & Walton W, Text Inst lnd, 11(1970) 219.2 Viswanathan G, Munshi V G & Ukidve A V, Indian Text

J, 99(5) (Feb. 1989) 42-44.

96 INDIAN J. FIBRE TEXT. RES., JUNE 1995

3 SlackJ K,J Text Inst, 61 (1970) T428-T437.

4 Walton W, J Text Inst, 59 (1968) 365-378.

5 Douglas K & Hattanschwiler P, Text Technol Im, (1989)339.

6 Uster news bulletin, No. 35 (Zellweger Uster Ltd), Sept.1986.

7 Operaung manual; high speed analysers 5815A, 581OA,5909A, Pan No. 57.02895, 2nd edn (Rockland ScientificCorporation, Rockleigh, NJ07647).

8 Ukidve A V, Studies on quality aspects of textile yarns,Ph.D. thesis, University of Bombay, Bombay, 1992.

9 Basic and practice of the evenness testing manual, PanNo. 460-7091 (Keisokki Kogyo Co. Ltd., Osaka 533, Ja-pan) 1986,59-60.

10 Manual for Uster spectrograph, Pan 'Il, Pubn No. 133826e.(Zellweger Uster Ltd., Switzerland) 1959,7.

Appendix I-Settings selectedSettings on SHM

Adjustable disc 1 mmSensitivity 100

Damping 1

Material speed 60 yards/min

Settings on SAGeneral setting for synchronizing with SHM

Voltage 2 vpk (voltage peak)Calibration 10 mV/EU

Spectrograph (TO)Type of octaveNo. of passage

CalibrationFrequency ranges

ThirdTwo

10mV/EU30-12000 cpm and 1.5-600 cpm