The document discusses defects that can occur in knitted fabrics. It begins by defining a fabric defect as an abnormality that spoils the fabric's appearance and affects its performance. There are many types of defects that can be caused by a variety of reasons. Specific defects mentioned include knots, which come from yarn winding and can cause breaks during knitting. Factors that influence the rate of end breaks due to knots are then discussed, such as knitting pattern, yarn type, tension, stitch depth, and machine settings. The document also mentions that computer vision methods like texture recognition can be used to detect common fabric defects like cracks, holes, and stains.

1. Hailay kidane,wollo university,hailaykidane@gmail.com

3. defect of the knitted fabric
 A defect of the knitted fabric is an abnormality
which spoils the aesthetics i.e. the clean & uniform
appearance of the fabric & effects the performance
parameters, like; dimensional stability etc.
 A defect of the knitted fabric is an abnormality
which spoils the aesthetics i.e. the clean & uniform
appearance of the fabric & effects the performance
parameters, like; dimensional stability etc.
There are various types of defects which
occur in the Knitted fabrics of all types
caused by a variety of reasons. The same
type of defects may occur in the fabric
due to a variety of different causes .
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3Hailay kidane

4. Knots are yarn faults that
come from winding.
Although the size of knitting
defect due to a knot is smaller
than that due to a yarnfault,the
knot causes the end breakage in
knitting and the machine
stoppage
Knots are yarn faults that
come from winding.
Although the size of knitting
defect due to a knot is smaller
than that due to a yarnfault,the
knot causes the end breakage in
knitting and the machine
stoppage

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7. knitting defect due to knot is
almost hole.
Knot yarn leads to end breakage(near
the knot) the breakage is due to
sticking or jamming.
Since knots turn freely in the direction
vertical to the yarn axis to pass easily
through the surface of knitting
elements and old loops, knots hardly
stick to them
Knot yarn leads to end breakage(near
the knot) the breakage is due to
sticking or jamming.
Since knots turn freely in the direction
vertical to the yarn axis to pass easily
through the surface of knitting
elements and old loops, knots hardly
stick to them
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8. (b) the space between the dial needle hook
or the latch and the old loop,
(c) the space between the dial needle head
and the dial verge,
(d) the space between the cylinder needle
hook or the latch and the old loop,
(e) the space between the cylinder needle
head and the cylinder verge
(b) the space between the dial needle hook
or the latch and the old loop,
(c) the space between the dial needle head
and the dial verge,
(d) the space between the cylinder needle
hook or the latch and the old loop,
(e) the space between the cylinder needle
head and the cylinder verge

9. end breakages due to the knot
in the lxl rib knitting zone occur in the following three
steps:
1) Jam of knots in the space: When the knot size is larger than
the space in the case of (e), knots jam the space in the case of
(d) as shown in Fig. 1, and then knots jam continuously the
space in the case of (e). This state continues until the cylinder
needle reaches the knitting point
2) Increase of yam tension: When knots jam the space, the
yam from the input side is not fed into the section mn in
Fig. l above.
Since the increase of yarn length in the section mn with the
descent of the cylinder needle has to be compensated by
the yam
elongation and the robbing-back, the yam tension in mn
increases rapidly in the 1 x 1 rib knitting zone.
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Hailay kidane

10. Con…
3 End breakages: When the yam tension in mn greater
than the knot strength, the end breakage occurs at any
point in mn, that is, near the knot on the take-down
side.
4) Factors that a fect end
breakage rate(EBR)
4) Factors that a fect end
breakage rate(EBR)
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11. Con..
a)Increase
yarn tension
Increase
EBR%
Increasing the depth
of stitch draw leads to
increase yarn tension
Plane knitting
High rate of tension
 due shorter initial length
Similar RB% with RIB
1×1 RIB knitting
 Less rate of tension
 due to longer yarn
initial length
Plane knitting
High rate of tension
 due shorter initial length
Similar RB% with RIB
Cotton
Higher yarn tension
Due to less
elongation
1×1 RIB knitting
 Less rate of tension
 due to longer yarn
initial length
Wrosted
Lesser yarn tension due
to high elongation
Higher RB% due to less
friction
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12. Con..
b)Increasing
of stitch
draw
Increase
EBR%
depth of stitch draw is the
vertical distance between the
upper surface of the dial
needle and the knitting
The stitch length of 1 x 1 rib knitted
fabrics increases with the increase of the
depth of stitch draw, as in the case of
plain weft knitted fabrics
The stitch length of 1 x 1 rib knitted
fabrics increases with the increase of the
depth of stitch draw, as in the case of
plain weft knitted fabrics
The increasing rate of EBR with the depth of
stitch draw for the cotton yarn is more than
that for the worstedyarn.Thisisprobably due to
the difference in the value of u and the yam
elongation.6/21/2017 8:56 PM 12Hailay kidane

13. Con..
c)Increase
input
tension
Increase
EBR%
As the input tension increases
stitch length decreases due to
elongation means that increasing
in EBR%
Plane knitting
High rate of EBR
 due shorter initial length and
increasing rate of yarn tension.
1×1 RIB knitting
Less rate of RBR
 due to longer yarn
initial length in (mn)
fig 1
Plane knitting
High rate of EBR
 due shorter initial length and
increasing rate of yarn tension.
Cotton
Higher EBR with
input tension
Due to less
elongation
1×1 RIB knitting
Less rate of RBR
 due to longer yarn
initial length in (mn)
fig 1
Wrosted
Lesser EBR with the
input tension due to high
elongation
Higher RB% due to less
friction
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14. Con..
D)Increasin
g of take
down weight
Increase
EBR%
EBR for cotton and wrosted
yarns increases with the
increase of the takedown
weight, probably due to the
decrease of %RB
EBR for cotton and wrosted
yarns increases with the
increase of the takedown
weight, probably due to the
decrease of %RB
increasing the fabric take-down load
increased the yarn force in the plain-weft
knitting zone .
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15. Con..
E) Effect of
Cam angle
As the cam angle is changed from
50° to 56°, EBR for the
worsted yarn decreases from 8.5%
to 5.6%. Since the number
of yarn/metal contact surfaces in
knitting zone decreases with
the increase of the cam angle
As the cam angle is changed from
50° to 56°, EBR for the
worsted yarn decreases from 8.5%
to 5.6%. Since the number
of yarn/metal contact surfaces in
knitting zone decreases with
the increase of the cam angle
EBR decreases with the increase
of the cam angle.
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Hailay kidane

16. Summary.

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18. Con…
Texturing is knitting fabric deffect
inspection system aided by computer
vision
By the ff methods.
co-occurrence matrices,
the discrete Fourier transform,
 wavelets,
 Gabor, and
clustering.(highly effective method)
Texturing is knitting fabric deffect
inspection system aided by computer
vision
By the ff methods.
co-occurrence matrices,
the discrete Fourier transform,
 wavelets,
 Gabor, and
clustering.(highly effective method)
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19. Con..
The major defect classes are
cracks
 holes
vertical stripes
 horizontal stripes
 soil freckles,
The major defect classes are
cracks
 holes
vertical stripes
 horizontal stripes
 soil freckles,
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20. Chart below shows The success rate of
detecting defects in fabric corresponding to
different texture recognition methods
80
100
120
vertical stripe
0
20
40
60
80
horizontal stripe
soilfreckle
crack
hole
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Hailay kidane

21. THANK
YOU
6/21/2017 8:56 PM Hailay kidane 21
THANK
YOU

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