The amount of twist imparted to yarn during spinning is important for several reasons: 1) Twist gives strength to strands so they can withstand strain during unwinding and processing. 2) More twist is needed for finer rovings compared to coarser rovings. Longer cotton fibers also require less twist than shorter fibers. 3) The level of twist inserted typically ranges from 0.7 to 2 turns per inch for cotton rovings, with higher twist reducing production rates and increasing costs.

1. Twistingand Amounts ofTwist for DifferentMaterials – why is the amount of twistin a yarn
important
Nuruzzaman Sayed
EBTX:160301262
Subject: Weaving Technology 1
Northern University Bangladesh
Email: sayedgdpm@gmail.com
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2. 
Twistingsection/Twistingand Amounts of Twist for DifferentMaterials – why isthe amount of twist
in a yarn important :
The rovingcomingout of the frontdeliveryrolleristhreadedthroughthe topof the flyer,passes
throughitshollowlegaroundthe presserarmon to the bobbin.The purpose of providingtwistinroving
isto give the strand sufficientstrengthtowithstandthe strainduringunwindinginthe creel of the ring

3. frame.The insertionof twistisachievedbythe rotationof the flyer.Twistleveldependsonflyerspeed
and deliveryspeedof the speedframe.The increase intwistreducesthe productivecapacityof the
machine,soitis generallyusedinarange as limitedaspossible.The relationshipbetweenthe twistand
the aforementionedfactorsisgivenasfollows:
Since the rotary speedof the flyerisconstantsothe amountof twistinsertedperunitlengthdepends
uponthe deliveryrate of the frontdeliveryrollers.
False twistingdevicesare usedonthe flyerstoaddfalse twistwhenthe rovingistwistedbetweenthe
frontrollerandthe flyer.Because of thissupplementarytwist,the rovingisstronglytwisted,andthis
reducesthe breakage rate.False twistingdeviceisalsocalled“twistcrown.”

4. The level of twistimpartedinthe speedframe processvarieswiththe staple of the cottonandthe hank
of the roving.Longercottonrequireslesstwistbecauseindividual fibersextendfurtherinthe strandand
thushelpto bindthemtogethermore securelythandoshortfibers.Finerrovingrequiresmore twist
comparedwithcoarserroving.The level of twistinsertedforcottonat the rovingframe isabout0.7 to 2
TPI.Highertwistinspeedframe reducesthe productionrate andthusincreasesthe costof production.
On the otherhand verylowtwistmakesthe rovingweakanditcan break duringthe package winding.
Principle ofWinding
❶ Bobbinleadingprinciple(Forcottonspinning)
❷ Flyerleadingprinciple(Forjute spinning)
Bobbin leadingprinciple (NB > NF)
In Bobbinleadingthe bobbinwindsitrounditself andthe bobbinspeedisalwaysmore thanthe flyer
speed.Butthe speedof bobbindecreasesasitgetslargerindiameter.

6. Flyerleadingprinciple (NF > NB)
In flyerleadingthe flyerwrapsthe rovinguponthe bobbininthisthe speedof flyerisconstantbut
alwaysmore thanthe bobbin.The bobbinstartingatcertainspeedwhenempty,mustgraduallyincrease
itsrate of revolutionasitgetslargerin diameter.