Indian Journal of Fibre & Textile ResearchVol. 20, December 1995, pp. 176-180

A study on measures to reduce infrequent yarn faults - Development of anattachment

A Kanthimathinathan; M Kathirvel, K Gnanasekar, R Hariharan & K P ChellamaniThe South India Textile Research Association, Coimbatore 641 014, India

Received 14 February 1995; revised- received and accepted 1 June 1995

A device has been designed and fabricated to be used at the back zone of ring frame to control the highincidence ofiong thin faults, particularly at wider back zone settings. Trials conducted with this device show asignificant reduction (about 70%) in long thin and thick faults. Use of this device at the back zone of ring framedoes not affect the yarn evenness. However, Uster thin and thick places show a significant reduction. Mill leveltrials also confirm the above findings.

Keywords: Back zone setting, Classirnat faults, Fault control bar, Roving twist multiplier

1 IntroductionDetailed surveys of the mixing and yarn quality in

more than I()()mills exporting yarns and fabrics havebeen done! by CfRAs during 1991-92.As per SITRAsurvey, the overall quality of export yarnscorresponds to Uster 57% rating in coarse counts,70% rating in medium and fine counts and 84% ratingin superfine counts. The various infrequent yarnfaults measured by the Uster Classimat System arealso very high. In coarse and medium counts, theinfrequent faults on an average meet Uster 70%standards and in fine counts, the fault levelcorresponds to as high as Uster 85% standards".Shah- has shown that long thin faults (H + I) aremanyfolds higher than Uster 50% levels. Best valuesof long thick faults (E + F + G) compare well withUster 25% levels in most of the cases but the averagevalues of these faults are worse than even 50% Usterlevels.

Substantial reduction in Classimat faults isreported to occur" by using a narrow bottom frontzone setting in speed frame. In ring frame, wider topfront zone setting results in excessive Classimat yarnfaults. But, in this study, no mention is made about theeffect of wider back zone setting in ring frame. Thesurvey" by SITRA on "Measures to produce yarnsmeeting international quality standards for export"has shown that use of wider back zone setting in ringframe (60-65 mm) and lesser breakdraft (1.14-1.3) isprevalent in most of the mills covered in the survey. Ithas also been observed that wider back zone settingwith lesser break draft improves yarn quality in termsofUster imperfections. However, the effect of wider

back zone setting in ring frame on Classimat longlength faults has not been covered in this survey.Hence, the present study has been undertaken tostudy the effect of wider back zone setting in ringframe on long length Classimat faults, and to suggestmeasures to control long length Classimat faults atwider back zone settings in ring frames.

2 Preliminary Study on the Influence of Back ZoneSetting in Ring Frame on Frequent and InfrequentYarn FaultsTo reconfirm the influence of wider back zone

settings in ring frame on Uster imperfections and longlength Classimat faults, this study was conducted forthree counts, viz. 30s K, 40s K and 60s K. Evennessand imperfections at three different back zonesettings in ring frame (Table I) clearly show that there

Table I-Evenness and imperfections at different back zonesettings

Count Back zone Evenness Uster imperfections/Itxn) msetting U%

mm Thin & thick places Neps

30s K 51 15.6 1218 159055 15.8 1262 161260 15.2 1034 1490

40s K 51 16.1 1272 102655 15.7 1138 115260 15.·2 924 909

60sK 51 17.6 2119 211955 17.2 1876 229160 17.1 1895 2393

KANTHIMATHINATHAN et af .. MEASURES TO REDUCE INFREQUENT YARN FAULTS 177

is a distinct trend for the evenness and imperfectionsto improve with wider back zone settings in ringframe. Even though the difference in evenness andimperfections at 51 mm and 60 mm of ring framesetting is not statistically significant in individualcases, the difference becomes highly significanttaking all the counts together. This means that theimprovement in evenness and imperfections withwider ring frame back zone setting is real andconsistent.

In the case of wider back zone setting with optimumbreak draft, twist in roving is broken up in a moregradual manner which, in turn, helps to avoidundrafted ends and short slubs in the yarn. If the slubis of a very high magnitude, it results in end breaks. Onthe other hand, if the slub is of a smaller magnitude, itis incorporated in the yarn and counted as Usterimperfections.

However, the large scale adoption of wider backzone setting in ring frame critically depends on itsinfluence in infrequent yarn faults which areimportant from the point of view of the performanceof the yarn in weaving preparatory as well as duringthe weaving and knitting processes and theappearance and appeal characteristics of the fabrics.

The long thin and thick faults in yarn at differentback zone settings are given in Table 2. Both longthick and thin faults increase with wider back zonesetting in ring frame. Between 51 mm and 60 mm ofback zone settings, the increase is rather statisticallysignificant. The probable reason for the increase inlong thin and thick faults at wider back zone settingcould be the relatively high level of short fibre contentin Indian cottons. The high short fibre content inIndian cottons is supposed to result in someuncontrolled fibre movement in the back zone. Thisuncontrolled fibre movement creates mass variationsat the back zone which are extended in length by theamount of draft in the main zone of the ring frame.Hence, these mass variations are counted asinfrequent long thick and thin faults.

Therefore, unless some mechanism/method isdevised to control the movement of short fibres in theback zone .and thereby to control the tendency ofClassimat faults to increase with wider back zonesetting, the benefit of using wider back zone settingtowards producing yarns with less imperfections cannot be fully realized.

3 Design and Development of a Fault Control Bar(FeD)In almost all the modern drawframes,an

attachment is provided at the front zone to control themovement of fibres during drafting. Adoption of a

similar concept may help to control fibre movementat the back zone of ring frame and thereby to controlthe tendency of Classimat faults to increase at thewider back zone setting. Accordingly, a fault controlbar has been designed and fabricated. However,towards optimizing the configuration of FCB, 4different designs were made and their effect onClassimat faults evaluated. The 4 designs made areshown in Fig.l.

Exhaustive studies made using 4 different barsshowed that FCB of the type shown in Fig.1 c givesbetter results. The results are given in Appendix I.FCB-I C was used for further large-scale trials. Thepositioning of FCB in the drafting zone of ring frameis schematically-shown in Fig.2. The device consists ofa holder (I) which is clamped to the arm bar of thedrafting system in the ring frame. The holder holdsthe long bar (2) which is projected towards thedrafting system between top arms. The fault controlbar (3) is connected to this long bar with the help of asetting unit (4). The FCB could be positioned inbetween the middle and back bottom rollers at araised level to the line offlow of material. The FCBextends over the length between the roller stands.

3.] Effect of FCD on Classimat FaultsUsing FCB, two counts, viz. 40s K and 40s C, were

produced. 40s Combed yarn was produced with 18%noil extraction. The major process parameters are

Table 2-Long thick and thin faults-at different back zonesettings

Long thick faults Long thin faults(E+ F+G)/Iakh m (HI + II)/Iakhm

Count Back zonesetting

mm

30s K 511624700

6997941180145020902379

515560515560515560

416188417386618099

40s K

60s K

Fig. I-Designs of fault control bar

178 INDIAN J. FIBRE TEXT. RES., DECEMBER 1995

given in the Appendix II. Classimat long thick and thinfaults for the two counts while using FCB in ringframe are given in Table 3. In this experiment, ringframe back zone setting was maintained at 60 mm.For comparative purposes, Classimat faults withoutusing FCB in ring frame are also given in Table 3.

At 60 mm setting, while using FCB the long thinfaults decreased by about 80% and the long thickfaults by'about 60% as compared to that obtainablewithout using FCB in 40s K yarn. It may be seen fromTable 2 that in medium and fine counts, Classimatlong thick and thin faults, on an average, increase byabout 70% when the back zone setting in ring frame isincreased from 51 mm to 60 mm. Hence, the broadindication is that the level ofClassimat faults (longthin and long thick) at 60 mm back zone setting withFCB is more or less equivalent to that obtained at 51mm back zone setting without FCB.

Fig. 2-A device for the reduction of long length faults in ringframe [l-holder, 2-long bar, 3-fault control bar, and

4-setting unit)

In the case of 40s carded yarn, while using FCB thelong thick faults decreased by 75% and the long thinfaults by 40%. The extent of decrease in faults here israther low as compared to that in 40s K. This is due tothe fact that the basic level oflong thin faults itselfislower in 40s C. This is again attributed to the relativelylower level of short fibre content in 40s C mixing.

3.2 Effect of FCB on Evenness and Uster ImperfectionsIt has been established beyond doubt from the

above studies that the introduction of FCB helps todecrease the Classimat long thin and thick faultssubstantially. However, to find out the effect of FCBon evenness and imperfections, a controlled studywas conducted for two counts and the results arepresented in Table 3. It is evident from this table thatthe use of FCB decreases the Uster imperfections(thin and thick), on an average, by about 50% inaddition to decreasing the Classimat long thick andthin faults. The effect of FCB on evenness is notsignificant.

3.3 Effect ofFCB on Long Leogtb Faults While Using Roving withHigher Twist Multiplier

Shah" has shown that the frequency of long thinand thick faults decreases by about 30% with the useof higher roving twist multiplier. No draft problemswere observed on the ring spinning machine in thecase of roving material having higher twist levels. Itwas, therefore, considered of interest to see theinfluence of FCB on yarn faults while using rovingwith higher TM. Accordingly, a study was conductedwith a higher roving TM of 1.4 (Count, 40s K,

Table 3-Effect of FCB on classimat faults, evenness and Uster imperfections

Count Back zone Long thick faults Long thin faults Evenness Imperfections/IOOO msetting (E + F +G)/Iakh IT. (HI + lJ)j1akh m (U%)

rom Thin & thick places NepsWihtout With Wihtout With Without With

FCB FCB FCB FCB FCB FCB Without With Without WithFCB FCB FCB FCB

40s K 60 12 5 446 93 13.6 13.4 1112 428 668 632

40s C 60 25 6 23 13 11.6 11.5 485 298 222 208

RovingTM

Back zonesetting

rom

Classimat faultsl1akh m

Table 4-Effect of FCB while using roving with higher twist multiplier for 40s K count

Uster imperfections/lOOO m

Long thick Long thin Thin & thick places Neps

WB

630

WOB WB

1.40 60 17 15WOB- Wihtout bar; and WB-With bar

WOB

171

WOB

1143

WB

453

WOB

614

WB

68

KANTHIMATHINATHAN et aI.. MEASURES TO REDUCE INFREQUENT yARN FAULTS 179

Table 5-Mill level trials using FCB

Mill Count Ring frame Long thick fault: Long thin faultsNo. back zone (E+ F+G)/ (Hl+ II)!

setting lakh m lakhmmm

WOB WB WOB WB

38sHosiery 51 24.2 12.5 36.0 12,3

2 50sCardedwarp 60 45.0 27.0 800 390

3 60sCombed 60 61.0 10.0 5503 3089

WOB-Without bar; and W~With bar

Nominal TM, 1.25) and the results are given in Table4. It is observed that by using FeB, long thin and thickfaults decreased by about 60% in 40s K yarn evenwhen roving with higher TM is used. It may, however,be noted that the extent of decrease (60%) inClassimat faults due to FCB (for roving of higherTM) is slightly on the lower side as compared to thatobtained while using roving of nominal TM (70%).However;further studies are required to confirm thistrend.

While using roving of higher TM the imperfectionsalso decrease (about 60%) due to the incorporation ofFeB in the back zone of ring frame. It is of interest tonote that the extent of decrease in imperfections athigher level of rovingTM is more or less same as thatobtained in the case of normal roving TM while usingFeB. Hence, irrespective of roving TM (within therange covered), FCB helps to control long lengthfaults as well as Uster imperfections.

4 Mill Level TrialsTo supplement the finding at SITRA pilot mill,

trials were conducted in 3 member mills of SITRAwith and without using SITRA's FCB in ring frame.The counts produced include 38s carded hosiery, 50scarded and 60s combed. The results are given in Table5. It is observed that 60scombed yarn shows substarnialreduction in terms of long thin and thick faults onincorporation of SITRA's FCB at the back zone ofthe ring frame. The extent of decrease is 50-65% inlong thin faults and4O-50o/~ in long thick faults in all .the three mills.

5 Conclusio~5.1 At wider ring frame back zone settings, the Usterimperfections, particularly thick and thin places, decre-

ase, probably due to the gradual breaking up of twist inthe roving. However, the Oassimat long thin and thickfaults increase, probably due to the uncontrolled move-ment of short fibres during drafting.

5.2 The tendency of Classimat long thick and thin faultsto increase at wider back zone setting of ring frame iscontrolled by the use of fault control bar (FeB) desig-ned and fabricated at SITRA.

S.3 Use of FeB at ring frame decreased the long thinfaults by 60-80% and the long thick faults by about70%.

5.4 FCB also decreased the Uster imperfections. Whileusing FCB at 60 mm back zone setting, the various yarnimperfections, on an average, decreased by about50%.

5.5 While using a roving of 1.40TM (normal TM, 1.25),FCB decreased the Classimat long thin and thick fa-ults by about 60%.

5.6 Mill level trials also, by and large, confirm the findi-ngs ofSITRA pilot mill studies. In mill level trials, byincorporating FeB at the ring frame, long thin andthick faults decreased by more than 50%.

AcknowledgementThe authors are thankful to MrT V Ratnam, Advis-

or, SITRA, for guidance throughout this work and toMr K Sellamuthu, General Manager, Sree Shanmugh-avel Mills, Dindigul, for permission to conduct the exp-eriments in their mills and also to use the testing instru-ments at their R&D laboratories. They are also thank-ful to two other member mills for conducting trials us-ing FeB at their units and to their colleagues, particula-rly Mr NRamakrishnan, in Spinning and Textile Phys-ics Division for help at various stages of this project.

ReferencesI Measures to improve the quality of export yams. A joint report of

ATIRA, BTRA, SITRA and NITRA (BTRA, Bombay).1992.

2 Seshadri S & Ramakrishnan N, A study on the quality of exportyams, SITRA resea~ch report. 36(7) (1991).

3 Shah P H, Measures for reducing long thin faults in cotton yamsthrough appropriate actions at speed and ring frames.Proceedings of the 34thjoint technological conference of A TIRA.BTRA. SITRA and NITRA (ATIRA, Ahmedabad), 1993.53-58.

4 Chellamani P, Kanthirnanthinathan A & Karthikeyan S,Measures to produce yarns meeting international qualitystandards for export. Mill control report No.7 (SITRA,Coimbatore), April 1991.

180 INDIAN J. FIBRE TF.XT. RES., DECEMBER 199'1

AppeDdix I-Putiealars ofabe optimizatioil IriaI ofabe deslp ofFCB

[Count, 30sC; Drafting system- SKF PK 225;Backzone settingat ring frame, 60 mm; and Break draft,l.3]

Classimat Without With barfault type bar

Short thick 4769Long thick 64Long thin 423

A

450843

340

B

449539

318

C

421135

.247

D

436962

385

Appeadix II-Major .pMCe18parameten adopted

Process parameter 40s K 40s C

Card sliver hank, NeComber noil extraction, %Finisher drawing sliver hank, NeRoving hank, NeRoving TMRing frame back zonesetting"mmSpindle speed, rpm

0.1518.00.151.5

1.40 1.25 1.406Oand7~

---14000"----

0.15

0.151.5

1.25