TITLE OF PAPER - Centrum Textil

2 nd INTERNATIONAL TEXTILE, CLOTHING & DESIGN CONFERENCE – Magic World of Textiles
October 03 rd to 06 th 2004, DUBROVNIK, CROATIA
STEREOMETRIC ARRANGEMENT OF YARNS IN FABRIC
Iva MERTOVA
Abstract:
This article deals with evaluation of structure of fabrics due to changes of weft sett and fabric finishing and
type of yarn on spatial arrangement and yarn‘s deformation in fabrics using main geometrical characteristics.
Arrangement of yarns in fabric is monitoring on cotton fabrics in plain weave in cut of fabric and in plain of
fabric.
Keywords Cotton fabric in plain weave, binding wave, binding point, deformation of yarn
1. Introduction
It is impossible to take binding wave as plane curve, it is necessary to mind its three-dimensional form, see
figure 1. Deviation of thread’s projection into plane of fabrics of linear shape results in different values of
thread spacing. This irregular location of threads can influence on air permeability, absorbency, cover factor,
thermal insulating and mechanical properties of fabrics.
Geometry and deformation of yarn in fabrics can be given and influenced by set of factors: process of
weaving, thread count, weave, yarn properties (fineness, twist, type) and finishing of the fabrics.
On technology, the yarn is exposed to stress what leads to its deformation. Deformation of yarn is usually
combination of bend, torsion and lateral compression and tensile axial elongation. It leads to compression,
flattening and increasing of packing density of the yarns, what results in modification of internal structure of
yarns. Significant impact on yarn cross-section deformation has first of all yarn bend and lateral stress.
Originally idealized circular cross-section of threads is deformed on elliptical or Kemp‘s cross-section.
Flattening of yarn’s cross-section influences for example in thickness, bending rigidity, areal covering, hand
evaluation, air permeability and it is one of criteria of construction and designing of fabrics.
Figure 1: Examples of yarn’s arrangement in plane of fabric
It is possible to monitor separately three-dimensional geometry and deformation of yarn, namely in cut of
binding wave of fabric or in projection into plane of fabric. In this contribution deal with influence of weft sett,
fabrics finishing and yarn type on spatial arrangement and yarn‘s deformation in fabrics using main
geometrical characteristics. Experiments were carried out on twelve fabrics: B16, B20, B24, A14, A16,5,
A19, R16, R20, R24, R14, R16,5 and R19. The First six are treated “applying of finishing agent” and rest is
gray. The warp yarns were sized. Fabrics were washed and dried on fixation frame. Numbers behind letters
A, B and R mean the warp threads per cm on machine. Experiment is done on cotton fabrics in plain weave
in two ways:
a) By monitoring of arrangement of yarn binding wave (procedure of soft sections, measurement dates by
use image analyses)
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2 nd INTERNATIONAL TEXTILE, CLOTHING & DESIGN CONFERENCE – Magic World of Textiles
October 03 rd to 06 th 2004, DUBROVNIK, CROATIA
b) By monitoring yarn geometry in plain of fabrics (scanning of pictures of fabrics, modification of pictures
and measurement dates by use of image analyses).
Both of procedures are compared.
2. Yarn’s geometry in binding wave
Yarn’s geometry in binding wave is monitoring by sett of geometrical parameters. These parameters
describe yarn waviness in fabric’s cut and yarn's deformation in binding point.
2.1 Yarn’s deformation in binding point
In contact point of two yarns, consequently in binding point, there is compression and enlargement of yarn.
Inner structure of yarn changes is depending on this deformation. The yarn cross section is deformed by the
bending and compression. Original circular cross-sectional shape changes to Kemp’s cross-section. This
shape may be changed to elliptical cross section, with general axes A, B. Where A is enlargement, B is
compression, see figure 2.
Figure 2 Deformed cross section of yarn in binding point
Geometrical parameters were measured from the images of textile cross sections. Warp thread spacing p 1
[µm], weft thread spacing p 2 [µm], warp enlargement A 1 [µm], weft enlargement A 2 [µm], warp compression
B 1 [µm], weft compression B 2 [µm] and amplitudes of warp and weft binding waves h 1 and h 2. , were
measured by means of image analysis on figure 3. From the measured data of enlargement and
compression are calculated values of flattening of yarn in binding point
γ = A/B (1)
Figure 3: Cut of warp binding wave
The influence of weft sett, of finishing of fabric and type of yarn on yarn’s geometry in binding point is
discussed with reference to flattening parameter. It is plotted in figure 4.
Parameters
2
1,9
1,8
1,7
1,6
1,5
Flattening of yarn
A1/B1[1]
A2/B2[1]
B 16 B 20 B 24 R 16 R 20 R 24
Fabric
Parameters
2,6
2,4
2,2
2
1,8
1,6
Flattening of yarn
A1/B1[1]
a. b.
A2/B2[1]
A 14 A 16,5 A 19 R 14 R 16,5 R 19
Fabric
Figure 4: Dependence of yarn’s flattening in fabric’s binding point on weft thread count and finish of fabrics: a) fabrics
from single yarn, b) fabrics from ply yarn
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2 nd INTERNATIONAL TEXTILE, CLOTHING & DESIGN CONFERENCE – Magic World of Textiles
October 03 rd to 06 th 2004, DUBROVNIK, CROATIA
From values of flattening in binding point, it was found: Increasing weft sett hasn’t influence on values of
yarn’s flattening in binding point on fabric from single yarn. But increasing weft sett on fabric from ply yarn
influences yarns flattening. Finishing of fabric influences flattening. Weft yarns are more deformed in the
finished fabric. Warp yarns are more deformed in the gray fabric by contrast.
2.2 Waviness of yarn in cut of fabric
Waviness of yarn in cut of fabric is described with warp and weft thread spacing, see figure 5; and with warp
and weft amplitude of binding wave, see figure 6. Difference between values of warp thread spacing isn’t
statistically insignificant in gray and finished fabrics too. Values of warp thread spacing are different in
dependence on weft thread count. From experiment it was found, that the weft threads spacing decreases
with increasing of weft thread count for all fabrics. Increasing weft sett hasn’t influence on weft thread
spacing.
In consequence with finishing, warp thread spacing of finished fabric is lower than warp thread spacing of
gray fabric; even the original sett on the machine is the same. The difference is statistically insignificant.
Finishing doesn’t influence values of thread spacing.
Warp and weft thread spacing
Warp and weft thread spacing
p1[µm]
p2[µm]
p1[µm]
p2[µm]
Thread spacing
700
650
600
550
500
450
400
B 16 B 20 B 24 R 16 R 20
Fabric
Thread spacing
800
700
600
500
400
A 14 A 16,5 A 19 R14 R16,5 R19
Fabric
a. b.
Figure 5: Dependence of thread spacing on weft thread count and finishing of fabrics: a) fabrics from single yarn; b)
fabrics from ply yarn
Mean value of warp amplitude of binding wave decrease with increasing weft thread count. Mean value of
weft amplitude of binding wave increase with increasing weft thread count for all fabric; without reference to
finishing of fabric and type of yarn. Weft thread spacing decreases and length of binding wave increases with
increasing weft thread count. It means, that longer yarn’s segment is bent more than shorter. So, increasing
weft thread count influences geometry of all fabrics. For fabric from single yarn, ply yarn, for gray or finished
too.
Warp and weft high of binding wave
Warp and weft high of binding wave
h1[µm]
h2[µm]
h1[µm]
h2[µm]
High of binding wave
210
190
170
150
130
B 16 B 20 B 24 R 16 R 20 R 24
Fabric
High of binding wave
340
290
240
190
140
A 14 A 16,5 A 19 R 14 R 16,5 R 19
Fabric
a. b.
Figure 6: Dependence of amplitude of binding wave on weft thread count and finish of fabrics: a) fabrics from single
yarn; b) fabrics from ply yarn
Influence of finishing on amplitude of binding wave is showed through flattening of yarns in binding point and
through thread spacing. Values of yarn’s flattening are generally higher for gray fabric and thread spacing
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2 nd INTERNATIONAL TEXTILE, CLOTHING & DESIGN CONFERENCE – Magic World of Textiles
October 03 rd to 06 th 2004, DUBROVNIK, CROATIA
values are generally less for gray fabric. Consequently are high of warp thread of gray fabric higher than for
finished fabric.
2.3 Result
Generally it was found: It is impossible to tell, that deformation of yarn in binding point depends on change of
weft thread count for all fabrics. Deformation of yarn in binding point depends on weft thread count only for
fabric from twisted yarn.
Shape of binding wave (waviness) is described with warp and weft thread spacing and warp and weft
amplitude of binding wave for all fabric. Values of these parameters depend on change of weft thread count.
Fabric’s finishing influences all fabric parameters within thread spacing. It can be say that arrangement of
yarn in fabric depends on fabric’s finishing.
3. Yarn’s geometry in plane of fabric
Laboratory classification procedure was developed to measure of yarn’s geometry in plane of fabric image
analysis Lucia G to use (optimal size of sample and zoom, scanning of fabric’s picture, modification and
transformation of fabric’s picture to the same scanning dates from picture).
Every unloaded picture was processed in the same way to be like each other to detect boundary-line
between body yarn and gaps between separate yarns. Scanned coloured images were transformed
independently in RGB components. These RGB components (red, green and blue) are the same for all
images. Colour picture was then transformed on so-called overlay picture.
Another modification was morphological erosion and dilation of image. Erosion removes a layer of pixels all
around an object. An object with thinner sections compared to matrix structuring element breaks into two
parts. Dilation expands objects and structures in a binary image. Neighbouring objects are connected and
small holes are filled. Overlay image was transformed to binary image. Examples of binary images are
showed in figure 7.
a. b.
Figure 7: Binary image of a) fabrics from ply yarn; b) fabrics from single yarn
From binary images were measured data on function interactive length measurement. The influence of weft
sett and finishing and yarn’s type on fabric’s geometry is discussed with reference to gaps (distance between
two neighbours yarns) and to yarn’s diameter D 1 a D 2 between two binding points. These parameters are
changed unambiguously with weft thread count. Comparison of diameters D 1 , D 2 a D is showed in the figure
8. D is diameter of free yarn.
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2 nd INTERNATIONAL TEXTILE, CLOTHING & DESIGN CONFERENCE – Magic World of Textiles
October 03 rd to 06 th 2004, DUBROVNIK, CROATIA
Comparison of yarn's diameters
0,28
D1 D2 D Comparison of yarn's diameters
0,5
D1 D2 D
Diameter [mm]
0,26
0,24
0,22
Diameter [mm]
0,45
0,4
0,35
0,2
B16 B20 B24 R16 R20 R24
Fabric
0,3
A14 A165 A19 R14 R165 R19
Fabric
a. b.
Figure 8: Comparison of yarn’s diameters for a) fabrics from single yarn; b) fabrics from ply yarn
Difference between parameters values is statistically significant for gray and finished fabrics. Finishing of
fabric influences shape of binding wave in plane of fabric. In accordance with yarn’s diameter measured
between binding points it is possible to find: Weft yarns are more deformed in the finished fabric. Warp yarns
are more deformed in the gray fabric by contrast.
3.1 Comparison of woven-in yarn diameters D 1 , D 2 with enlargement in binding point of fabric A 1 , A 2
Diameters of woven-in yarns are measured in plane of fabric and enlargements of yarn in binding point are
measured in cut of binding wave of fabric. According to assumption are more deformed yarns in binding
point. Loading leads to compression of yarns and it is transferred to yarn’s section between two binding
points. The difference of yarn’s deformations in binding point and between two binding points is smaller for
finished fabrics than gray fabrics. Single yarn is more deformed than ply yarn.
Comparison of diameter and enlargement
A1 D1 A2 D2
0,5
Parameters [mm]
0,45
0,4
0,35
0,3
0,25
0,2
A14
A16,5
A19
R14
R16,5
R19
B16
Fabric
B20
B24
R16
R20
R24
Figure 9: Comparison of warp and weft diameters and warp and weft enlargement for all fabrics.
3.2 Result
Generally it is possible to tell for all fabrics: Values of weft and warp parameters decrease with increasing
weft thread count and the difference between values is statistically significant for all fabric. Mean values of
parameters are higher for gray fabrics than for finished fabrics. So, waviness in plane of fabric depended on
weft thread count. All parameters values of all fabrics are depended on fabric’s finishing. It can be say that
finishing influences arrangement of yarn in plane of fabric.
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2 nd INTERNATIONAL TEXTILE, CLOTHING & DESIGN CONFERENCE – Magic World of Textiles
October 03 rd to 06 th 2004, DUBROVNIK, CROATIA
4. Conclusion
Single yarn’s deformation in binding point isn’t depended on weft sett. In contrast, ply yarn’s deformation is
depended on weft thread count. Shape of binding wave is described with thread spacing and amplitude of
binding wave. Weft thread count influences values of these parameters. Arrangement of yarn in cut of fabric
is depend on fabric’s finishing. Finishing doesn’t influence values of thread spacing. Arrangement of yarn
and deformation in plane of fabric is depend on weft thread count and on fabric’s finishing.
Comparison of both methodic was made with respect to thread spacing. The difference between values from
both methodic doesn’t exceed 15% for all fabrics. For any fabric are these values the same.
Acknowledgements:
This work was supported by the research project LN 00 B090 of Czech Ministry of Education.
References
[1] Nosek, S.: Structure and geometry of fabrics (in Czech), VÚB, Usti nad Orlici, (1974)
[2] Kovar, R.: Structure and properties of flat fabrics (in Czech), TU of Liberec, 80-7083-676-8,
Liberec, (2003)
[3] Drasarova, J.: Thread deformation in fabric’s binding point (in Czech). Liberec, (2003)
[4] Composite authors: Internal standards. Research centre Textile, Liberec, (2002)
Iva MERTOVA, M.Sc.
Technical university of Liberec
Hálkova 6, 461 17 Liberec, Czech Republic
Phone: +(420) (48) 535 3628 Fax: +(420) (48) 535 3542 E-mail: iva_mertova@vslib.cz
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