Root Causes Analysis of knitted
Fabric Faults & Their Remedies
Causes of Fabric faults due to yarn
Causes of Fabric faults due to knitting
Causes of Fabric faults due to Dyeing &
Due to increasing the demand for quality knitted fabrics,
high quality requirements are today greater since customer
has become more aware of “Non-quality" problems, in
order to avoid fabric rejection, knitting mills have to
produce fabrics of high quality, constantly. Detection of
faults during production of knitted fabric with circular
knitting machine is crucial for improved quality and
productivity. Any variation to the knitting process need to
be investigated and corrected. The high quality standard
can be guaran-teed incorporating appropriate quality
assurance. Industrial analysis indicate that quality can be
improved, and defect cost minimized, by monitoring of the
circular knitting process.
Our aim of this project is to study on root causes
analysis of knitted fabric faults. To do so we have
collected various type of faults from many
industries and classify them in a systematic
Causes of Fabric faults due to Yarn
Almost all the defects appearing in the horizontal
direction, in the knitted fabric are, yarn related.
These defects are mainly:
IV) Thick & thin place
Barriness defect appears
in the Knitted fabric, in
the form of horizontal
stripes of uniform or
Causes Of Barriness:
factors which may cause or contribute to barre are
listed as follows:
Yarn formation /supply
Failure to control fiber diameter (micronaire
or denier) from lay down to lay down.
Too high a C.V. of micronaire in the lay
down for a given mill's opening line blending
Failure to control the fiber color in the mix
(grayness Rd, yellowness +b).
Poor blending of fiber in opening through finisher
Mixing yarns of different counts.
Mixing yarns from different spinning systems.
Mixing yarns with different twist level/twist direction.
Mixing yarns with different degrees of hairiness.
Mixing yarns with different amounts of wax.
Excessive back winding or abrasion during this
Improper stitch length at a feed.
Improper tension at a feed.
Variation in fabric take-up from loose to tight.
Excessive lint build-up.
Variation in oil content.
Worn needles, which generally produce length
Uneven cylinder height needles (wavy barre).
Double feed end.
Ensure uniform Yarn Tension on all the feeders.
The average Count variation in the lot, should
not be more than + 0.3
Ensure that the yarn being used for Knitting is
of the same Lot / Merge no.
Ensure that the hardness of, all the yarn
packages, is uniform, using a hardness tester.
Spirality appears in the
form of a twisted
garment, after washing.
The seams on both the
sides of the garment
displace, from their
position & appear on the
front & back of the
A) Influence of yarn properties
B) Influence of fabric properties:
Fabric Stitch length:
A dimensional change resulting in a decrease in the
length or width of a specimen subjected to specified
conditions is known shrinkage. Shrinkage is mainly
due to yarn swelling and the resulting crimp increase
during washing in case of cotton fabrics
Causes of Shrinkage:
Twist factor: twist factor increases so that
shrinkage will be increases,
Stitch length: stitch length increases so that
shrinkage will be increases,
GSM: GSM increases so that shrinkage will be
Remedies of Shrinkage
Keep the Grey Fabric in loose plated form,
immediately after the roll is cut.
Store the finished fabric also in the plated form & not
in the roll form.
Allow the fabric to relax properly, before it is cut.
Give maximum overfeed to the fabric, during the
processing, on the Stenter, Compactor & the
(IV) Thick & Thin Places
It causes due to yarn
problem. If thick &
thin places remain in
yam & fabric is knitted
with that yarn, then,
this problem found in
Fig: Thick Thin Place
Causes of Fabric faults due to Knitting
Almost all the defects appearing in the vertical
direction, in the knitted fabrics, are as a cause of bad
Knitting Elements. And some defects appear randomly
in the knitted fabrics, due to the wrong knitting
machine settings & that of the machine parts
About Different type of faults are discuses bellow
Cracks Or Holes
Local holes obtained when yarn breaks during
Presence of knot in yarn.
Weak places in yarn.
Yarn tension too high.
Yarn too dry.
Yarn - guide not properly
Poorly lubricated yarn. Fig: Hole
Use of flat knots.
Yarn regularity control.
Yarn consumption & coulier re-adjustment.
Precise yarn - guide resetting.
Use of protective filter creel.
Same drive for both knit & tuck
Curved needle latch.
Different drive have to maintained
Needle has to change.
Needle has no change.
Fig: Pin Hole
Presence of dead fibers & other foreign materials, such
as; dyed fibers, husk & synthetic fibers etc.
Dead fibers do not pick up color during Dyeing.
Fig: Fly contamination
Use rich fiber mixing for the yarns, to be used for
Knitting, in order to have less dead fibers, appearing in
Rigid control measures in the Blow Room, to prevent
the mixing of foreign matters in the Cotton mixing
High Yarn Tension
Bad Setting of the Yarn Feeders
Old & Worn out Needle set
Ensure uniform & the right Yarn
tension on all the feeders.
Keep the recommended gap,
between the Yarn Feeders & the
Periodically change the complete
set of needles.
Fig: Needle Broken
Sinker not cleans.
Defected /broken sinker.
When darts deposited in
sinker, it is raised & causes
Sinker has to be clean.
It should be checked that the
sinker having correct
thickness and depth.
Replacement of defected
Fig: sinker mark
Stains or Oil Lines
Grease & Oil stains from the
unguarded moving machine
Fabric touching the floors &
other soiled places, during
transportation, in the trolleys.
Stains appear as spots or patches of grease, oil or dyes of
different color, in a neat & clean finished fabric surface
Fig: Stain or oil line
Wash & clean the dyeing machine thoroughly, after
dyeing every dye lot.
Follow the dyeing cycle of Light- Medium- Dark
shades & then the reverse the cycle, while dyeing the
All the lubricated moving machine parts, should be
protected, with safety guards
Fabric Press Off
Fabric press off appears, as a big or small hole in the
fabric, caused due to the interruption of the, loop
forming process, as a result of the yarn breakage, or
closed needle hooks.
End breakage on feeders, with
all needles knitting.
Yarn feeder remaining in lifted
up position, due to which, the
yarn doesn’t get fed in the
hooks of the needles.
Fig: Press off
Needle detectors, should be set precisely, to detect the
closed needles & prevent the fabric tube from
completely pressing off.
Proper yarn tension should be maintained, on all the
Fail to catch the Lycra yarn by needle.
Low tension of Lycra yarn.
Lycra yarn breakage.
Faulty auto stop motion
Ensure the feed of lycra yarn to every
The tension of lycra yarn should be
Auto stop motion should work
Fig: Lycra out
Low tension of Lycra yarn
Fail to catch the Lycra yarn by needle
Ensure the feed of lycra yarn to
The tension of lycra yarn should be
Usually caused by a thick or
heavy place in yarn or by ling
getting onto yarn feeds.
By using Good quality yarn
Causes of Fabric faults Due To
Dyeing & Finishing
The Dyeing and finishing related defects are, as follows
Dead cotton on dyed
Shade Variation/Uneven Shade
Sometimes, there appears to be a
difference in the depth of shade
between the roll to roll & from place
to place, in the same roll. The defect
will show up clearly in the garments
manufactured from such fabric.
Shade variation can be as a result of
mixing of the fabrics of two different
Shade variation is also caused by the
variation in the process parameters
i.e. Time, Temperature & Speed etc.
from one fabric roll, to the other.
Fig: Shade Variation/Uneven Shade
Shade variation can appear to be in fabrics with GSM variation,
caused due to the uneven stretching, unequal fabric overfeed %
Ensure that the grey fabric used for one shade is knitted from
the same lot of the yarn.
Ensure that the same process parameters (Width, Overfeed,
Temperature & Machine Speed etc.) are used, for each roll of a
Pin Hole Damage:
Oxidation of the knitting oil/lubricant on
the fabric stored for a long duration.
Presence of sharp metallic part in some
parts of machine
Presence of heavy metal ions in peroxide
Check presence of any sharp object in
Provide magnetic filters in water/ steam
Fig: Pin Hole Damage
In knit dyeing crease mark is a common dyeing
More cycle time.
Faulty plaiting device.
Slack on tight selvedge causes creases at an angle to
Incorrectly set bowed-expander.
Variation of heating and cooling rate.
Improper fabric movement.
Anti- creasing agents are used to avoid crease mark
Fig: Crease Mark
These are most often caused by
operators not correctly mixing and
thoroughly dissolving the dyestuff, in
the right amount of water.
Dye bath hardness.
Not agitation of dyestuff.
Use adequate amount sequestrate to
lower bath hardness.
Fig: Dye Spots
Dead Cotton On Dyed Cotton:
Poor quality cotton
More abrasion during process
Try to minimize the abrasion
Use acid Cellulosic softener
Fig: Dead Cotton On Dyed Cotton
It causes due to operator
carelessness. Sometimes workers do
not slit fabric through slitting mark.
Operators have to slit fabric
through slitting mark or fed fabric
in slitting m/c in proper way so that
m/c can slit fabric through slitting
Fig: Wrong Slitting
Overflow heat on the fabric during
Incorrect speed of stenter m/c
during heat setting.
Provide correct temperature in
To keep correct speed of stenter
Fig: Lycra Burn
If the fabric is wet condition in long time.
During drying the fabric if any part of the fabric is wet then
it can occur.
Un proper fixing during dyeing
To use short time for wet conditioning of the fabric.
Equal drying of the fabric.
Proper fixing during dyeing.
Due to dirty finishing floor.
Unclean the trolley of finishing floor.
Due to unclean the m/c surface.
Unclean the compactor m/c after using the
varies color of fabrics.
Drop the footstep in white fabric.
To keep clean the finishing floor.
Clean the trolley of finishing floor.
To clean the m/c surface.
Clean the compactor m/c after using varies
color of fabrics.
Detection of faults during production of knitted fabric is crucial
for improved quality and productivity.
This presentation will present and discuss the detection of faults
and malfunctions during the production remedies of knitted
We believe that our work will help the knitters to identify the
source of de-tected faults & proposes specific solutions for
theses faults causes. So Knitters can take necessary remedial
steps to overcome the faults.
1. Yarn Manufacturing Technology
Link : http://www.facebook.com/pages/Yarn-Manufacturing-
2. Fabric Manufacturing Technology
Link : http://www.facebook.com/pages/Fabric-Manufacturing-
3. Garments Manufacturing Technology
Link : http://www.facebook.com/pages/Garments-Manufacturing-
3. Wet processing Technology
Link : http://www.facebook.com/pages/Wet-Processing-Technology-Dyeing-
Link : http://www.facebook.com/pages/Fashion-Design-and-
My Facebook Textile related Pages
http://www.textilelab.blogspot.com (Visit My Blog for more Info )