Prepared By : Mazadul Hasan sheshir
13th Batch (session 2009-2013)
Department : Wet Processing Technology
Blog : www. Textilelab.blogspot.com (visit)
Department Of Textile Engineering
I/A 251,252 Tejgaon Dhaka Bangladesh
Prepared By :
3/26/2014DRAWING & TEXTURISING
What is Drawing?
Purpose of Drawing.
Principle of Drawing.
Errors in Drawing.
What is texturising?
Purpose of texturising.
Steps of texturising
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With the exception of silk ,all filaments are manufactured from
man-made materials. These materials, however don’t occur in
fibrous in nature. They are primarily made from chemicals that
must be formed and solidified into fiber form. Synthetic fibers
have been developed that posses describable characteristics, such
ass a high softening point to allow for ironing, high tensile
strength , adequate stiffness, and describable yarn quality. In their
origional state, the fiber–forming polymers are normally solids
and therefore must be first converted into a liquid form to be
suitable for extrusion. After extrusion there are some operation is
done for complete this process and to produce a good quality of
yarn. From these we will discuss about Drawing ant Texturising.
-Drawing is very important process of spinning.
-This process is used to increase the orientation
of polymer molecules.
-It produces filament with desired strength.
Fig. Two Stage Drawing Process
-Drawing process increases tensile
strength and hardness of filament.
-It orients the polymer molecules
along the filament.
-Crystallinity increases due to the
orientation of polymer molecules.
Fig: Change in orientation of polymer molecules
High degree of orientation of polymer molecules
that tends to increase fibre stiffness.
Lower moisture absorption.
Unlimited breaking strength.
Transparency and luster.
Changed dyeing properties.
Resistance to penetration by foreign molecules.
What is Drawing?
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Historically , the term Drawing was used in connection with the draw
frame in staple spinning. Drafting was used regarding roller drafting
system in roving and ring spinning .Polymeric fibre drawing is an
important industrial process. The objective behind drawing fibres is to
induce molecular orientation in the fibre, thereby increasing their strength
in the direction of the stretch. That is, Extension of the filaments to many
times their original length. By means of this operation, the more or less
randomly oriented chain molecules are aligned in the longitudinal
direction and the filaments its defirutive stress-strain characteristics.
Purpose of Drawing:
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The prime purpose of drawing of a yarn is to a desirable quality for the
The orientation of the polymer molecules can be increased after the
spinning process by a subsequent drawing process.
To convert relatively week spun fibres to fibres with greater molecular
orientation and the resulting greater strength.
To produce a filament with a desired strength, accomplished by
inducing sufficient orientation of the polymer molecules along the axial
direction of the filament.
To produce fibres with the specific properties desired.
To increase the crystalline zone in fibres.
Principle of drawing:
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Consider a sample of the input material before and after discontinuous
drawing. If there were no losses in the process, the mass of the input
sample would be the same as it is after drawing. Let p be the packing
density, a the cross sectional area , l the sample length, piaili be the mass
in the input sample, and poaolo be the mass after drawing. It follows that;
piaili ≈ poaolo
And if the packing density is constant
pili ≈ polo
For the purely theoretical case, the change in cross sectional area is
inversely proportional to the change in length. This is discontinuous
drawing. However ,in production. The process of elongation takes place
continuously wit the input and output mass flows nominally constant.
Thus , the formula can be restated to say that the cross sectional area is
inversely proportional to the speed ratio. In practice this is modified by
changes in the packing density and small losses have to be taken into
account , but it forms the basis of all drawing.
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The drawing process of a fibre involves passing the fibre tow over a
series of rollers. The rollers rotate at specified constant angular
velocities, each faster than the older. In some processes all the draw is
introduced in one step, in a single stage of feed and take-up rollers. This
single draw can result in fibre breakage so it is customary to involve more
than one more draw processes in the industries.
Molecular orientation during drawing
A typical two-stage drawing process:
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Bechtel at. Al gave a model for a two-stage draw process in which most of
the draw was provided in the first stage( between 2.2 and 2.7 draw ratio)
and a relatively smaller draw (1.1-1.2) in the second stage. As the number
of stages is increased, it is possible to keep each free span and roller at a
different temperature and induce the maximum molecular orientation in
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Place of Origin: Shandong China (Mainland)
Brand Name: TONGDA
Model Number: FA-316A
Type: Spinning Production Line
Spinning Method: Ring Spinning
Textile machine: draw frame
Draw frame: high speed draw frame
Delivery number: 2 holes
Maxmium output speed: 600m/min
Total drafting mutiple: 5-14
Drafting style: 5 over 4 with pressure bar
Feeding sliver number: 6-8
Mainframe OAD: 2790*950*1645mm
Motor power: 4.0kw
Impact of drawing
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The degree of alignment of fibre molecules affects the properties of a
fibre in several way;
Fibres change in appearance as they are drawn. In the undrawn
stage , nylon is usually dull and opaque. As the filaments are drawn and
molecule orientation increase, the filaments acquire the transparency and
The more closely the molecules pack together, the greater is the
ultimate strength, or breaking strength, of the fibre.
This increase in ultimate strength is accompanied by a decrease in
the amount of elongation that the fibre can sustain before reaching its
Because the closely packed molecules no longer have great freedom
of movement , a high degree of orientation also tend to increase fibre
stiffness and rigidity.
Increased resistance to penetration by foreign molecules also
improves the general chemical stability of a fibre, since highly oriented
fibres are more resistant to chemical attack.
Errors in drawing
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Where there is a number of drafting stages, the results are
cumulative and the range of error wavelengths can be very large.
Yarns show not only an extremely large range of errors translate
into faults in the fabric. The end result of these irregularities is that
the fabrics made from the yarns show undesirable patterning known
as moiré or barrě , which reduces their values.
What is Texturising?
Texturing is a procedure used to increase the volume and the elasticity of a
filament fibres. The essential properties of textured yarns and the products
made from them are softness, fullness, a high degree of elasticity, thermal
insulation and moist transporting properties. All yarns which can be shaped
by heat are suitable for texturing. The prime purpose of texturing filament
yarn is to create a bulky structure.
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The process of introducing crimp, loop, coils to
continuous filament yarn is called Texturizing. It
stabilizes the POY through heating and drawing.
Two types of manmade POY can be textured-
Nylon (Used in manufacturing of ladies hosiery)
Polyester (Used in apparel & home furnishing)
- Introduce mechanically by passing the filament
between gear like rollers.
- Produced chemically by controlling coagulation of a
filament in order to create asymmetric cross-section
in the fibre.
-The twist geometry is set by cooling the yarn in a
highly twisted state.
-This process is applied with drawing process.
-False-twist is applied for Nylon and Polyester.
- Introduced crimp are like as the shape of knitted loop
- Yarn is knitted into tubular fabric
- Then unraveled to produced textured yarn
-This method is used with a single type of yarn or with
a blend of filament yarns
-It is carried out by feeding a wet yarn or a dry yarn
Plus a small amount of water into a high-speed jet of
-Yarns textured in such a process contain a large
number of very fine filaments
Purpose of texturing:
The prime purpose of texturing filament yarn is to create a bulky
structure that is desirable for the following reason;
The voids in the structure cause the material to have good
The voids in the structure change the density of the
material(Which makes possible a lightweight yarn with good covering
The disorganized (or less organized) surface of the yarn gives
dispersed light reflections, which, in turn, give a desirable matte
The sponge like structure feels softer than a lean twisted flat yarn.
The crimped or coiled filament structure gives a lower effective
modulus of elasticity to the structure when compare with that of a flat
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Steps of texturising:
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Deform the filament.
Set the deformation.
Remove the deformation.
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Real twist Texturising
False twist Texturising
Knit de knit
Air jet Texturising
Edge crimping method
Texturising by co-extrusion
1. Real twist Texturising:
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Hare a batch of package of yarn was then taken from the twister and
placed in an autoclave. The temperature of the yarn was raised above
Tg and then allowed to cool. The product taken from the autoclave
was non-twist lively or dead, but the fibre deformations were set into
their newly twisted shapes. To develop the bulk, it was necessary to
untwist the yarns until the filament were approximately parallel and
separated, and then relax them
2. False twist Texturising:
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Here partially oriented yarn(POY) is fed
into a heating zone(200-230 c). Where
insert twist is set. The yarn then passes
through a cooling zone to a twist unit.
Consisting of a series of revolving discs.
Which insert twist ,when twisted yarn is
relaxed, the yarn retains a thermal memory,
which produces yarn with a high
bulk/stretch potential. Bulk/ stretch can be
controlled by passing the yarn through a
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As Texturising speeds rise, they approach the speed used for filament drawing
and it becomes possible to contemplate a merger between the two operations.
There are two forms of draw texturising ;
Draw Texturing Machine
4. Air jet Texturising:
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In this method of texturing, yarns led through
the turbulent region of a air jet at a rate faster
than if is drawn off on the far side of the jet, in
the jet, the yarn structure is opened , loops are
locked inside and others are locked on the
surface of the yarn. An example of this method
is the taslam process;
Air jet textured yarn.
5. Knit de knit:
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Knit -de-Knit texturing is used on drawn
fibre in order to produce crimp of a knitted
loop shape. In this process a yarn is knitted
into a tubular fabric, set in place by means of
heat, and then unraveled to produce textured
6. Stuffer box:
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The crimping unit consists of
two feed rolls and a brass tube
stuffer box. By compressing the
yarn into the heated stuffer
box, the individual filaments are
caused to fold or bend at a sharp
angle, while being
simultaneously set by a heating
7. Gear crimping:
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In this method filament is run between a pair of intermeshing gear
wheels. The resultants yarn is left with the impression of the gear wheel
8.Edge crimping method:
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In this method of Texturising. Thermoplastic filaments in a heated and
stretched condition are drawn over a crimping edge and cooled. Edge-
Crimping machine are make align yarn.
9. Texturising by co-extrusion:
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Co-extrusion is where two or more
polymer components are extruded
through the same nozzle to produce a
filament with stripes of different
polymers. It is difficult to manage more
than two components; thus two
component system are likely to be most
significant commercially. There are two
distinct possibilities. The first is to have
the stripes firmly bonded to each other in
such a fashion that treatment will cause it
to curl or otherwise texture in the manner
of a bi-component yarn. The second is to
make the stripes have little or no
bonding, in which case the filament can
be decomposed into a series of finer
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As already pointed out, textured yarns are
characterized by higher extensibility,
elasticity and bulkiness than flat yarns
Schematic longitudinal view of textured
Among the various properties, generally
assessed with methods similar to those used
for other types of yarn, there is a method of
particular importance and for specific use,
termed crimp contraction (or crimp
elasticity).This property is essentially
assessed on false-twist yarns and is defined
as “the contraction of a textured yarn due to
crimp development, expressed as
percentage rate of the stretched out (not
crimped) yarn length”
Properties of textured yarns:
Difference between texturising
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What type of yarns can be textured:
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Synthetic filament yarns made from
Nylon and polypropylene.
Polyester yarns are normally in the
range between 50 and 300 den, with the
emphasis on 75 and 150 den.
Nylon yarns are in the range from 15-
The majority of fine hosiery yarns
being 20 den and coarser yarns being
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