Textile Engineering

1. Drawframe
Input:cardsliver
Output:Drawnsliver
##DifferencebetweencardsliverandDrawnsliver:
Cardsliver Drawnsliver
Fiberorientationinalldirection Fiberorientationintheparallel
directiontothesliveraxis
Manyfibersareprojectedoutfrom
sliver
Lessfibersareprojectedoutfrom
sliver
Hooks(leading&trailing)are
present
Lesshooks(leading&trailing)are
present
Irregularwt./unitlength Regularwt./unitlength
Cardsliverhaslessstrength Drawnsliverhasmorestrength
##Bothinputandoutputofadrawframeissliver.Thenwhywe
usedrawframe??
Answer: From apurelycommercialpointofview draw frameisoflittle
significance.Butitsinfluenceonqualityandevennessisgreater.The
cardedslivercontainsfiberswhichareorientedinvariousdirectionsand
theyarehooked.Theyentangledwithoneanotherandtheirweightperunit
lengthishigh.Theyareirregularandcontainsomeimpurities.Sotheyneed
aprocessforeliminatingtheseerrors.
Incottonspinninglinedrawframeisthedefinitivecompensationpointfor
eliminatingerrors.Thisdrawframe:-
 Straightenthefibersinsliver.
 Makethefibersmoreorlessparallel.
 Reducetheweightperunitlengthofsliver.
 Removedustfromsliver.
 Makeveryperfectblendingoffibers.

2. Workingprincipleofadrawframe:
1.Feedingofmaterial:Fourtoeightcardslivercan(feedcan)are
fedatbelowofcreelframe.Thesesliversarethecreeledandfedto
thedraftingarrangementthroughafeedrollerpairlocatedabove
eachfeedcantoenablethefeedinginacontrolledmanner.
2.Draftingofmaterial:Thesliversthenrunthroughthedrafting
arrangementwhererangeofdraftof4to12asrequiredisapplied.
Herestraightening,parallelization and attenuation operation take
place.
3.Sliverformation:afterleavingthedraftingarrangementapackage
offiberiscalleddraftedweb,lackingsignificantcohesionbetween
fibers is produced.In this condition the fibers do notform a
transportableintermediateproductinordertoavoiddisintegrationof
theweb.Theintermediatetransportableproductsliverisproduced
aftercondensingthedraftingwebpassingthroughthecondensing
tube(trumpet)justafterleavingthedraftingarrangement.
4.Deliveryofmaterial:Thissliveristhenguidedthroughatubeviaa
passageofthecoilertubegearintoadeliverycaninwhichitmustbe
laidincleancoilswithoptimalutilizationofthespaceinthecan.To
enablethecantotakeupasmuchmaterialaspossible,thesliveris

3. compressedbypassingitthroughcalendaringrollers.
5.Doffingofmaterial:Thefilledcanispreparedforthedoffing
operation.Thereiscantrackforfeed-inoftheemptycananddelivery
-outofthefilledcan.
Mainobjectivesofadrawframe:
1.Toremovemajorityofhookspresentincardsliver
2.Toincreaseuniformityofsliver
Objectsofdrawframe:
1.Tostraightenthehookedfibersinthecardslivers
2.Tomakethem lieinamannerparalleltotheirneighborsandtothe
sliveraxis.
3.Toimprovetheuniformityandevennessofthesliversbydoubling
4.Toproduceamoreuniformsliverofdefiniteweight/unitlength.
5.Toreduceweightperunitlengthofsliver
6.Toremovedustfromsliver
7.Tomakeperfectmixing/blendingofthesliver
Tasksofdrawframe:
1.Equalizing:oneofthemaintasksofthedraw frameisimproving
evennessovershort,medium andespeciallylongterm variation.
Equalizingisalwaysperformedduringdrawingbyafirstprocess
namelydoublingandcanoptionallyalsobeperformedbyasecond
processnamelyautolevelling.Thesliversfedtothedrawframefrom
thecardcontainsvariationsinthicknessthatistheyarenotregular.
Thedoublingprocessindrawframeimprovetheregularityofthefinal
sliverbyaveragingouttheweightvariationsexistinginsliversfedto
drawframe.
2.Parallelizingandstraightening:Toobtainoptimum strengthinyarn,
thefibersmustbearrangedparallelinthefibersstrand.Thedraw
framehasthetaskofcreatingthisparallelarrangement.Itfulfilsthis
taskbythewayofthedraftsinceeverydraftingstepleadsto

4. straighteningofthefibers.
3.Blending:Thoughablendingcanbeachievedinmodernblowroom
process,furtherblendingaftercardimprovesthecompositionof
fibersinthesliver.Thepracticeoffeedingseveralslivers(doubling)
sidebysidethroughthedraw frameandrecombiningthem atthe
frontgivesaverygoodblendingoffibersintheindividualsliverand
thismakesthefinalslivermoreuniform thancardsliverinfiber
composition.
4.Dustremoval:Thedraw frameisagooddustremovingmachine
becausetherearehighlevelsoffibertofiberandfibertometal
frictionduringdrafting.Onhighperformancedrawframesequipped
withappropriatesuctionorremovalsystem morethan80% ofthe
incomingdustisextracted.
Q.whatistheinfluenceofdoublingonsliverquality?
Q.whatistheinfluenceofdraftingonsliverquality?
Definitionofdifferentterms:
1.Drawing:Aprocessinshortstaplespinninginwhichthesliversare
blended,doubled,levelledanddraftedbypassingthesliversthrough
aseriesofpairsofrollerseachpairmovingfasterthantheprevious
one.
2.Doubling:Theprocessofcombingtwoormoreslivers,rovingsor
yarnsintooneiscalleddoubling.
3.Drafting:Theactionofreducingtheweight/unitlengthofthefeed
materialbydrawingisknownasdrafting.
4.Creelinganddoffing:Theoperationofreplacingthecansoffeed
materialatthebackofthemachineandjoiningthenewcanfullof
slivertotheoldisknownascreelingandthatofremovingthefull
deliverycansfromthefrontofthemachineisknownasdoffing.
Featuresofmoderndrawframe:
1.Eliminationofmechanicalcausesofirregularity.Provideselectrical
controlautolevellingwhichgivesandmaintainshigherdegreeof
regularityindrawnsliver.
2.Highspeedrunning

5. 3.Pneumaticsuctiondevicesfordustremoval
4.Stopmotionsatstrategicpointstostopthemachinewhenneeded
5.Automaticcanchangers
6.Moremachinesperoperativeandlittleattentionneeded.Soreduces
laborcost
7.Improvedtoparmweightingsystem
Elementsofdraftingarrangement:
Bottom roller:Bottom rollersaremadeofsteelandaremountedinroller
strandsorinframesbymeansofneedleorballbearings.Theyare
positivelydrivenfrommaingeartransmission.
Onordertoimprovetheirabilitytocarrythefibersalong,theyareformed
withflutesofoneofthefollowingtypes.
a) Axialflutes
b) Spiralflutes
c)Knurledflutes
Toproller:Thetoprollersarenotpositivelydriven;theyaremountedbythe
meansofballbearings.Thesetoprollersaremadeofsteelandtheyare
coveredwiththickcoatingofsyntheticrubber.Animportantmatteravoid
thiscoatingisitshardness.Softrubberscoatingcangripthefiberstrand
moreperfectlythanthatofhardone,butsoftcoatingofrubberwearout

6. morequickly.
Hardnessofrubbercoatingontoprollersisspecifiedintermsofdegree
shore.
Softcoating->60-70degreeshore
Mediumcoating->70-90degreeshore
Hardcoating->Above90degreeshore
Toprollerpressure:Toclampthefibers,thetoprollersmustbeforcedout
athigh pressure towards the bottom rollers.This pressure can be
generatedby:
1.Loadingbymeansofdeadweight(nowobsolete)
2.Springweighting(themostusualform)
3.Hydraulicsystems(hardlyused)
4.Pneumaticweighting(theRietercompany)
5.Magneticweighting
Typesofdraftingarrangement:Earlydrawframeshadalmostexclusively4
over4rollerdraftingsystems.The3over4rollersystem wasdeveloped
outofthisearlierversionandthereafteramultitudeofnewformsemerged.
The drafting system maybe classified based on the form ofroller
arrangementcanbedescribedbelow:
1.Conventional4over4rollerdraftingsystem
2.3over4rollerdraftingarrangement
3.3over3rollerdrafting
4.4over3rollerdrafting
5.5over4rollerdrafting
4over3rollerdraftingarrangement:Thisisthemostwidelyuseddrafting
arrangementfordraw frames.Strictlyspeaking,thisisalsoa3roller
pressurebardraftingarrangementbutafourthrollerwithsomewhatlower
loadingisaddedtothedeliveryrollertoactasaguide.Thisleadstheweb
incurveroundthegroovedrollerdirectlyintothedeliverytrumpet,thereby

7. facilitatingtheformationofthesliver.Thetoprollersareuniform in
diameterandarelargeinordertokeepthestrainimposedinthemlow.
Draftcalculation:let,backrollerrpm=500&diameter=30mm
Middlerollerrpm=900&diameter=30mm
Frontrollerrpm=3000&diameter=40mm
Weknow,draft=
surfacespeedoffrontroller
surfacespeedofbackroller
= (surfacespeed=πdn)
3.1416×40×3000
3.1416×30×500
=8
Backdraft=
surfacespeedofmiddleroller
surfacespeedofbackroller
=
3.1416×30×900
3.1416×30×500
=1.8
Frontdraft=
surfacespeedoffrontroller
surfacespeedofmiddleroller
=
3.1416×40×3000
3.1416×30×900
=4.44
Totaldraft=backdraft×frontdraft
=1.8×4.44
=8

8. Requirementsofdraftingarrangement:
1.Simple,uncomplicatedconstruction
2.Stabledesignwithsmoothrunningoftheroller
3.A modeofoperationgivingahighqualityproductevenathigh
runningspeed
4.Highdegreeofflexibility(suitabilityforallrawmaterial,fiberlength,
sliverwt.)
5.Rapidandsimpleadjustabilityofrollerspacing
6.Rapidandsimpleadjustabilityofdraftlevel
7.Easeofmaintenanceandcleaning
Q.whatdoyoumeanbyrollersetting/rollerspacing/rollergauge?What
istheimportanceofrollersettingondraftingarrangement?
Answer:Inadrawframeitisnecessarytospacetherollersacertain
distanceapart.Thedistancefrom thecentreofonerollertothecentre
ofanotherisknownastherollersetting/rollerspacing/rollergauge.
Rollersettingmainlydependsonthestaplelengthoffiber.Iffiberstaple
lengthishighthenrollersettingmustbewide.Ontheotherhandiffiber
staplelengthislowthenrollersettingmustbeclose.
Factorsdependinguponthedraftingarrangement:
1.Diameteroftherollers
2.Hardnessoftoprollers
3.Pressureexertedbythetoprollers
4.Surfacecharacteristicsoftoprollers
5.Rollersetting/rollerspacing/rollergauge
6.Levelofdraft
7.Distributionofdraftbetweenvariousdraftingstages
Q.1. Adraw frameisrunningwith4-over-4draftingsystem.Please
distributethedraftbetweenvariousdraftingstages.(Sufficientdatawill

9. begiven)
2.A draw frameisrunningwith4-over-3draftingsystem.Please
distributethedraftbetweenvariousdraftingstages.(Sufficientdatawill
begiven)
Necessitiesofautostopmotion:
1.Thesliverrunoutfromthecreeledcan
2.Sliverbreaksinthecreel
3.Lappingupondraftingrollers
4.Ifsliverislappingbetweentrumpetandcalendarroller
5.Ifdeliverycanisfilledwithsliver
Ifautostopmotionisabsent:
1.Considerabledamagemaycausetomachine
2.Theoutputslivermaybethickorthin
3.Lappingupofdraftingorcalendarroller
4.Irregulardrafting
5.Excessoffullcan
6.Toomuchwasteproduce
7.Theyarnstrengthorrovingstrengthmayvaryfromplacetoplace
8.Anyoperatormusthavetoattendthemachinefulltimetostopitat
anyfault
Autolevelling:Autolevellingisanadditionaldevicewhichismeantfor
correctingthelineardensityvariationsinthedeliveredsliverbychanging
eitherthemaindraftorbackdraftofthedraftingsystem,accordingto
thefeedvariation.
Therearetwotypesofautolevellingsystems:
1.Openloopsystem
2.Closedloopsystem
Openloopautolevelling:Inopenloopautolevelerssensingisdoneat
thefeedingendandthecorrectionisdonebychangingeitheraback

10. draftormaindraftofthedraftingsystem.Mostofthedrawframeauto
levellersareopenloopautolevellers.
Closedloopautolevelling:Inclosedloopsystem,sensingisatthe
deliverysideandcorrectionisdonebychangingeitherabackdraftor
maindraftofthedraftingsystem.Mostoftheearliercardautolevellers
areclosedloopautolevellers.Butthelatestcardshavesensingatthe
feedrollersandaswellasatthedeliverycalendarrollers.Wecansay,
bothclosedloopandopenloopsystemsarebeingusedinsuchauto
levellers.
Letusdiscussaboutanautolevellersystem whichisbeingusedin
mostsuccessfuldrawframeslikeRSB-951,RSB-D-30etc.
Thissystem isanelectroniclevellingsystem.Themajorcomponentsin
thesystem arescanningroller,signalconverter,levellingCPU,servo
motor,Differentialgearbox.Function ofthe scanning rolleris to
measurethevariation inthefeedmaterial.Allsliversfedtothemachine
passthroughapairofscanningrollers.Oneofthescanningrollersis
moveableandanotherisfixed.
Thevariationsin slivermassoftheincoming sliversdisplacethe
scanningroller.Thedistancemovedbythescanningisproportionalto
the sliver mass fed. This displacement of scanning rollers is
transformedintovoltagebyasignalconverterandisfedtoanElectronic
Levelling processor.Itis the Electronic Levelling processorwhich
furnishesthecorrecttargetvaluetotheservomotor.

11. Deliveryspeedofthemachineandelectricsignalvaluesarrivedatby
theslivers fedarethetwoimportantsignalsforthecorrection.Servo
drivetakestheinformationandisconvertedinsuchawaythatservomotor
RPM and direction is decided forappropriate correction.Differential
gearingwithitscontrolledoutputspeeddrivesthemiddleandbackroller.
i.e.Sliverentryofthedraftingsystem.BecausetheservomotorRPM and
direction variesaccording to thefeed variation and theservo motor
generatesacontrolspeedofthedifferentialgearing,therequiredchangein
maindraftisaccomplished,compensatingfortheweightvariationofthe
sliverfed.
 Ifthesliversfedaretooheavy,theentryspeed(backandmiddle
rollerspeed)isreducedi.e.draftincreased
 Ifthesliversfedaretoolight,theentryspeedisincreasedi.e.draft
reduced
Deliveryspeed(thefrontrollerspeed)remainsconstantandhencethe
productionremainsconstant.
Mathematicalproblem:
1.Findoutthedraftofadrawframeifcardsliverwt.is70gr/yd,drawn
sliverwt.is75gr/yd,doublingratiois6:1.
2.Iffrontrollerrpmis5000anddiameteris40mmthenwhatwillbethe
deliveryspeedofthisdrawframe?
3.Findouttheproduction/hrinkgofadrawframeiffrontrollersurface
speed650m/min,drawnsliverwt.75gr/yd,efficiency90%.
4.Ina4over3draftingsystem,speedofbackrolleris500,diameterof
backrolleris35mm andtotaldraft8.45.Ifdrawnsliverwt.is75
gr/ydthenwhatwillbetheproductioninkg/hr.letefficiency90%.
5.Let,countofinputsliver72gr/yd,doubling,totaldraftandfrontroller
surfacespeedwereset8,8.7and700m/minrespectively.Findout
theproduction/dayofthisdrawframe.(efficiency88%).
6.Let,countofinputsliver70gr/yd,doublingratio8:1,backdraft1.8,
frontdraft4.4,backrollerrpm 500,diameterofbackroller30mm.
findouttheproduction/dayofthisdraw frame.Assumeefficiency
92%.