1. SPINSOTUTION
Whatarethemostcommon
Quality parameterstested
throughamodernEvenness
tester?Giveshort descrip-
tion for eachparameter.
. ^ 1
20
1 5
1 0
5
0
-5
-10
-20
Fig.1:RepresentationforDeviationRate
MathematicalRepresentationfor DeviationRate
Dlagramof1-5mcuttendn
A.
Followingqualiry pdrameters
mayobtainedthrougha modern
evennesstester:
1. U%orunevenness%.
2, CVmor % Coefficientofvariationof
mass.
3.
5.
6.
7.
8.
Imperfectionsi.e.Thic( Thin& neps
ofdifferentdiameters.
%DeviationRate.
Irregularitylndex.
RelativeCount.
YarnHairiness.
FD/kmor ForeignFibre(Dark).
Short description;
1, U 7o or unevenness0/o:Irregularity
or unevennessof mass.This indicates
the amount of overall mass variation
in % from the meanmassof the tested
sample.Valuesarebasedonthe 1 cm,cut
length.This shows the Overallamount
of massvariationoverthe test Iengthin
numericalvalue.
2. CVm or 0/oCoefficient of variation
ofmass: Thisnumericalvaluerepresent
to overallmassvariationbasedon a cur
lengthof onecm.
Thisshowstheoverallmagnitudeofmass
variationalonga materialandshowlittle
reactionto longterm massvariations.
3.lmperfections i.e.Thic Thin &neps
of different diameters: Impedection
are consideredas frequentlyoccurring
faultsandgenerallyrepresentedasasum
of Neps;Thick& Thin placesper km. of
yarn.The "0/0"levelmay be selectedfor
thick or thin placescorrespondsto the
6 |SpinningTextilesIjan-Feb2015
)-rD R , , . , : u ' . l 0 0 o t o
I
"ToT
crosssectionalincreaseor decreasein
yarn.
A thick or thin placeis countedifthe de-
creaseor increasesurpassesthe pre-set
%ovalue.A thickorthin placehasalength
correspondsifs fibre lengthfor example
30 mm for shortstaplefibres[i.e,Cotton,
etc.Jand60mmforlongstaplefibres[i,e,
Wool,polyesteretc.].
Thin placeconsideredasdecreaseof di-
ameterfrom meanvalueas:-300/0,- 400/0,
-50%o& -60 %owhilethickplacesconsid-
eredasincreasein diameterfrom mean
valueas:+35%,+ 500/s,+'70o/n& +7Q0o/n.
A yarn nep is countedif the yarn diam-
eter surpassesthe chosenvalue.The %
levelselectionofthe nepcorrespondsto
the cross-sectionalincreasein Frn.
A referencelengthof 1 mm for shortsta-
ple and4 mm for long staplefibrescon-
sideredfor countingof yarnneps.Neps
countedasincreasein yarndiameterof+
1400/0,+ 200o/o+2800/o& +400o/o.
4.0/oDeviationRate:The% deviation
Deviationratewasintroducedby the
JapanSpinnersInspectionFoundation
and generally used by fapanese
customersorspinningmills.
deviationexceedor fallsbelowa cenatn
Iimit.
Thecutlengthfactorin metersaverage
outtheshortethigherdeviations.
DR= Totalrelativelengthin % of all
deviationsof the masssignalwhich
surpassthelimit+/-X0/ooveratotaltest
lengthinmetecwiththecutlengthofthe
curvebeingy meterValueof 1.Sm cut
lengthand+/- 5 % limitusuallyuseoas
standardsetfings.ReferFig.1
5. lrregularity tndex The yarn ir-
regularityindexis the ratio of actually
measuredCV ascomparedto thetheo-
reticallyachievableCV. Thisshowhow
closeayarnachuliffegularity(i.e.CV.n)
w.rt theoreticalllrachievableirregular-
ity (i.e.CV-).
'I'he
indexisameasureof
howwellparticularfibreshavebeenpro-
cessedintoyams.
/r/
1,',6"* o; il'r"*h'ip = iJ:E
L vt,-
100
wnereLYtin----
v n
ratedescribesbywhatpercentagea mass n = No.offibres in yarncrosssection.

2. SP]IlSOLUTION
lrregularity index is usedto distinguish
thefollowingl
To comparethe yarn qualityof two
differentyarnlotofsamecountmade
from two differentfibres.
Similaryarns with differentcount
candirectlybe comparedwith each
otherto checkthesuitabilityof fibre
Qualityfora requirecountpattern.
6. Relative Count: The relative count
gives the mass deviation in %oof the
wholetest lengthof eachtest sample
as comparedto the averagemassof all
samples.
This value is an indicationof relative
count devialionand eountrariations
in betweenbobbins.The relativecount
measurementcannotprovidethe abso-
lute count measure,it's only showsthe
correlationwithrespectto between-bob-
bin variation.Relativecountdetermined
with the capacitivemethod.The mean
valueofthesampleisalwayssetaseither
100% or 0 %.Thecutlengthis variable
andmaybeselectedas50m,100m,200m
& 450mor asmanualinput,
7. Yarn Hairiness:Theratio of the total
lengthofprotrudingfibresin cmforeach
cm of yarn.The hairinessvalueis the
averageoI all theonecenrimeterhairi-
nessvaluewithin ayarntestsample.The
hairinessvJlueistheratiooftwolengths
hencethereis no unit. Evennesstester
alsoprovidesthe Standarddeviationof
hairinessas'sh"value.The"sh valueisa
measureofIheshorttermhdirinessvdri.
ation between1 cm cut lengthover the
wholeyarntestlength.
B.ForeignMatter:Somemoderneven-
nesstestersalsocompetentto detectthe
foreignmatters.The colouredforeignfi-
bresmeasuredthroughanopticalsensor
while to determinethe vegetablematter
a combinationof themassmeasurement
0f the capacitivesensorandthe optical
sensorlsused.
The foreignmattersensormeasuresall
foreignmatter and classifiesthe events
in the foreignmatter classmatrix. The
numberof foreignmatterFDincluding
vegetablematterandseedcoatsobtained
in resultstableasFD/Km.
I I SpinningTextilesIjan-Feb2015
[.
Unevennessor Um ozo: The
What is the basicdifference
betweenUo/o& CVmVo?
Unevennessis themostcommon
Parameterusedto expressmass
variationin a yarn.It is the percentage
mass deviationof the unit length of
materialand is causedby unevenfibre
distribution along the length.The U 0/o
is proportionateto the intensityof the
massvariationsaroundthe meanvalue.
ReferFig.2:
The deviationin massper unit length
i.e.al, a2, a3....etc.are representedas
blocksaboveandbelowthe meanvalue
dependinguponwhetherthe deviations
areontheposiliveor negativeside,If r
is the averagemassper unit length,then
the averagemassofthe fibrestrandover
a lengthof the yarn correspondingto
timeT isgivenby
The Um% may be expressesas:
al+ a2+ ....a,,100
A
Mass
ThereforeUm %omay be represented
bytheratiooftwoareasexpressedasa
percentage.
MathematicalRepresentation
In mathematicalformU %oisexpressed
asfollows:
flv tl
' / l " r " l
U...%:l-----:-xl00s-
X T
Coefficient of variation or CVm%o:
CVm% is representedto coefficientof
variation of massfor cut length of one
centimeter
The massvariationcan be considered
to conformapproximatelyto a normal
distributionwhena homogeneousfibre
compositionisavailable.ReferFig.3:
A measureof the size of thesemass
variationis the standardsdeviations,
whichisexpressedas:
X
Frg.2:Cf,rphicrlRepresentrtronof Llnevennes.
Time(T)
t(t-r.,I
n - I
a.: , , , , , , , , , , , , , T , , , , , , , , , . . . . . . . . . . . . - . v , . . . . . . , , . . . . . . . . . . 9 - . . . . - -. . . . . . : . : . : -
Time(T)--'+
Fig.3:CraphicalRepresentalionof Coefficientof VariationCVm0/0

3. SPINSOLUTION
The Coefficient of variation CVm 0/o
is defined as the standard deviation
expressedasa percentageofmean.
StandardDeYiationx 100
cv%:
Mean
MathematicalRepresentation:In math-
ematicalform,CV.% is expressedasfol-
lows:
cv-%:ry
Thelargedeviationsfromthemeanvalue
are much more intensivelytaken into
considerationinthecalculationofCVm0/o
ratherthan Um%dueto the squaringof
theterm ln nl. TheCVmis preferred
moreandmoreto the unevennessUm%o
value.
A.
What is relationshipbetween
IrregularityUmo/oandCVm%?
If thefibreassemblyrequiredto
betestedis normallydistributed
withrespecttoitsmassvariation,
then the relationshipbetweenUm % &
CVm% maybeestablishedasfollows
t_
l l , ^ -
sy CVmo - 1.25xU -oA
Cltn
Or Um"/o- -
1.25
Where an ideal normal distribution of
the fibre assemblycannotbe assumed,
aboveconversionfactorwill besubjectto
error Aboveconversionfactorvalid only
for asymmetricallydistributedmassvar-
iation,referFig,4,If the massvariation
is distributedasymmetricallyandassem-
blieswith frequentandaccentuatedthick
placesthe followingconversionmustbe
used.ReferFig.5 & Fig.6.
CVm%o> 1.25x Um%
If strong periodic mass variations are
availablein a fibre assemblythe follow-
ingcalculationfactormustbeused.Refer
Fig.7
C V m % < 1 . 2 5 x U m 7 0
10| SpinningTextilesIjan-Feb2015
Fig.4:AnormalSymmetricalDistribution.
Fig.5: Distributionshowingexcessivemeanvaluevariation.
Flg.6:AsymmetricalDlstribution.
Fig.7:Distributionshowingstrongperiodicvariations.
byMr.SunilKumarSharma,
Dy.GeneralManager
[QAD,PPC& CustomerCare]
LoknayaklNSSSGLtd.
Shahada,Nandurbar(MSl
Disclaimer:The views expressed;n this
sectionreflectsolelythe opinionof the
contributor'sanddonotrepresenttheviews
ofSPINNINGTEXTILESMagazine.Readersare
advisedto consultanexpertbeforeapplying
anysolutiongivenhere.
i[,'