Transcript 3.1.2 Hopsack weaves

Chapter Three
Derivatives of Elementary Weaves
These weaves are constructed by means of
developing elementary weaves.
They are derived by changing the floats, number of
shift, direction of diagonal lines, from plain, twill, and
sateen/satin weaves, and retain their structural features.
The derivatives of elementary
weaves include:
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3.1 Plain weave derivatives
3.2 Twill weave derivatives
3.3 Satin/sateen derivatives
3.1 Plain weave derivatives.
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3.1.1 Rib weaves
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3.1.2 Hopsack weaves
3.1.1 Rib weaves
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Rib weaves are obtained by extending the
plain weave in either warp or weft direction.
Two kinds of rib weave:
warp rib weaves
weft rib weaves
1. Warp rib weaves
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Warp ribs are
constructed by inserting
several picks in
succession into the same
shed of an ordinary plain
weave. This forms a rib
effect across the fabric.
(see Fig. 3.1)
● Regular warp rib
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The same number of
picks are inserted in each
successive rib, giving the
fabric a regular appearance.
See Fig. 3.3
This figure shows 3 picks
are inserted into each shed
● Irregular warp rib
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A variation in the width of
rib is achieved by inserting
different numbers of picks
into each successive shed. See
Fig. 3.4.
● The warp rib weave diagram is
drawn as the following steps.
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1) Calculating the weft repeat Ry :
Ry = numerator + denominator
Ro = 2
2) Drawing the first end
according to the fraction given.
3) Drawing the second end
opposite to the first one.
■ ■
■ ■
■ ■
■ ■
■ ■
■ ■
Example: 2/1 irregular warp rib
2. Weft rib weaves
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Weft ribs are constructed
with several warp threads used
as one when interlacing with
each pick in succession. They
form a vertical rib effect in the
fabric. (See Fig. 3.5 two ends are
used as one)
● Regular weft rib
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An regular number of ends are used to
form each rib, giving the fabric a regular
appearance. See Fig.3.6
Irregular weft rib
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A variation in the width of the rib is
achieved by varying the number of ends in
each successive rib, as shown in Fig. 3.7.
● The weft rib weave
diagram is drawn as following
1) Calculating the warp repeat
Ro.
Ro = numerator + denominator
Ry = 2
 2) Drawing the first pick
according to the fraction given.
 3) Drawing the second pick
opposite to the first one.
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■ ■
■■ ■■
■ ■
■■ ■■
Example: 2/1 Irregular weft rib
Notes:
Warp rib weaves produce ribs running weft-way
Shown in Fig.3.1
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Weft rib weaves produce ribs running warp-way
Shown in Fig.3.5
● Applications
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Rib gives a more flexible cloth than plain weave
and has many applications.
Fabrics are woven in silk, cotton, wool and
man-made fibers. Their end uses range from dress
fabrics, coats, suits, millinery, ribbons and wedding
to upholstery and drapery.
3.1.2 Hopsack weaves
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Hopsack weaves are constructed by
extending the plain weave both vertically
and horizontally. See Fig. 3.8
● Regular hopsack
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Regular hopsacks are woven with the same
number of ends and picks and the same yarn count.
Equal warp floats exchange with equal weft floats.
See Fig. 3.9
● Irregular hopsack
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Different units of hopsack are arranged
in one repeat, with the distribution of warp
or weft floats being equal or a
predominance of either. See Fig. 3.10
● The irregular hopsack diagram
is draw in following steps.
1) Calculating the repeat:
Ro = Ry = sum of the numerator +sum of the denominator
 2) Drawing the first end and first pick based on the
fraction.
 3) Based on the first pick, drawing the ends which have
warp float same to first end.
 4) Drawing the other ends opposite to the first one.
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●Applications
Hopsack weave fabrics are
less stiff than plain due to
its fewer intersections, and
they have smooth and
lustrous surface. Hopsacks
are suitable for Apparel,
drapery, and are often used
for selvedge of other fabrics.
Regular hopsack sample
Irregular hopsack sample
Home works:
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2.
3.
4.
5.
Drawing the weave diagrams
2/2 warp rib;
2/2 weft rib;
2/2 hopsack;
3/3 hopsack;
warp rib 2 2
1 2
6. 3/1 weft rib,
7. hopsack 3 2
3 2
8. hopsack
1 2
2 1