Defects in the Knitted Fabrics (SGS Project) (1)

5/24/2018 Defects in the Knitted Fabrics (SGS Project) (1)

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Defects in the Knitted Fabrics

Introduction:A defect in the knitted fabric is an abnormality, which spoils the aesthetics i.e. theclean & uniform appearance of the fabric & effects the performance parameters,like; dimensional stability etc.

here are !arious types of defects, which occur in the Knitted fabrics of all types,caused by a !ariety of reasons. he same type of defects may occur in the fabric,due to a !ariety of different causes e.". Drop #titches, #pirality. $rime causes ofthe fabric defects are, as follows;

%arns

Knittin" lements

Knittin" 'achine #ettin"s

Dyein"

Finishin"


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ypes of Defects :

Drop #titches or (oles

)arriness

#treakiness

Imperfections

#narlin"

*ontaminations

#pirality

+eedle ines

)roken +eedles

#inker ines

-il ines or #tains

)roken or 'issin" nds

Fabric $ress -ff

#urface (airiness & $ilin"

#na""in"

)owin"

Dyein" $atches

#oftener 'arks

#tains *olor Fadin"

#hade ariation

onal ariation

/et #0uee1er 'arks

Fold 'arks

*rease or 2ope 'arks

#kewin" or Dia"onal 3rain ines

#hrinka"e 3#' ariation

/idth ariation

*urlin" of d"es

'easurements


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*ate"ory of Defects:

%arn related defects

Almost all the defects appearin" in the hori1ontal direction,in the knittedfabric are, yarn related. hese defects are mainly;

)arriness

hick & hin lines

Dark or i"ht hori1ontal lines4due to the difference in dye pick

up5

Imperfections *ontaminations

#narlin"

#pirality

Knittin" lements related defects

Almost all the defects appearin" in the !ertical direction, in the knittedfabrics, are as a cause of bad Knittin" lements. hese defects are mainly ;

+eedle & #inker ines

Drop #titches etc.

'achine #ettin"s related Defects

hese defects appear randomly in the knitted fabrics, due to the wron" knittin"machine settin"s & that of the machine parts. he defects are mainly;

Drop #titches

%arn #treaks )arriness

Fabric press off

)roken nds

#pirality


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Dyein" related defectshe Dyein" related defects are, as follows;

Dyein" patches, #oftener 'arks

#hade !ariation

onal !ariation

*olor fadin" 4$oor *olor Fastness5

Dull shade

*rease or rope 'arks

Finishin" related defects

Defects caused, mainly due to the wron" process parameters are ;

(i"h #hrinka"e

#kewin"

#pirality

#urface (airiness & $illin"

onal !ariation #na""in" 4#harp points in the dyein" machine or trolley etc5

Fold 'arks

/et #0uee1er 'arks

3#' !ariation

Fabric /idth !ariation

*urlin" of #.6. Fabrics


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Drop #titches 4(oles5

Definition:

Drop #titches are randomly appearin" small or bi" holes of the, same or differentsi1e, which appear as defects, in the Knitted fabrics.

'a7or *auses:

(i"h %arn ension

%arn -!erfeed or 8nderfeed

(i"h Fabric ake Down ension

-bstructions in the yarn passa"e, due to the clo""in" of eyelets, yarn

"uides & tension discs, with wa9 & fluff etc.

Defects like; #lubs, +eps, Knots etc.

Incorrect "ap between the Dial & *ylinder rin"s.

2emedies:

nsure uniform yarn tension on all the feeders, with a ension 'eter.

2ate of yarn feed should be strictly re"ulated, as per the re0uired #titch

en"th.

he fabric tube should be 7ust like a fully inflated balloon, not too ti"ht or

too slack.

yelets & the %arn 3uides, should not ha!e, any fibers, fluff & wa9 etc.

stuck in them.


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he yarn bein" used, should ha!e no imperfections, like; #lubs, +eps &

bi" knots etc

he "ap between the *ylinder & the Dial should, be correctly ad7usted, as

per the knitted loop si1e.

)arriness

Definition:

)arriness defect appears in the Knitted fabric, in the form of hori1ontal stripes ofuniform or !ariable width.

*auses:

(i"h %arn ension

*ount ariation

'i9in" of the yarn lots

$acka"e hardness !ariation

2emedies:

nsure uniform %arn ension on all the feeders.

he a!era"e *ount !ariation in the lot, should not be more than .

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Defects in the Knitted Fabrics (SGS Project) (1)