The document discusses core spun yarns. Core spun yarns consist of a central core made of filament, elastane or staple fibers wrapped by a sheath of staple fibers. They can be produced using various spinning methods like ring spinning, rotor spinning, air jet spinning or friction spinning. Core spun yarns have applications as sewing threads and stretch fabrics due to properties derived from the core material. Production parameters like heater temperature and stretch ratio impact properties of core spun yarns like shrinkage and tenacity. Bulked acrylic yarns use a blend of relaxed and unrelaxed fibers to create bulk through fiber shrinkage upon heating after spinning.

1. Hailay kidane,wollo university,hailaykidane@gmail.com
Prepared by Hailay kidane Submitted to Dr.Bharani

3. The core spun yarns
 The core spun yarn consists of central core made
up of a filament or elastane or bundle of staple
fibers covered or wrapped by a sheath of staple
fibers. They are unique in yarn structure and
specific applications.
 The core spun yarn consists of central core made
up of a filament or elastane or bundle of staple
fibers covered or wrapped by a sheath of staple
fibers. They are unique in yarn structure and
specific applications.
Core span sewing threads
Polyester/cotton-cotton soft thread
Polyester/cotton-glazed thread
Polyester/polyester thread
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4. Con.. Raw materials for core yarn
spinning
High tenacity polyester
in multi or mono
filament, textured
filament forms.
Elastomeric
filament, like
lycra
Sheath covering
Cotton either in
pure form or in
blends with
synthetic fibres.
Man made fibres
such as
polyester,polyamide,
acrylic,viscose,moda
etc
High tenacity polyester
in multi or mono
filament, textured
filament forms.
High or medium
tenacity polyester
fibres,kevlar nomex,etc
Elastomeric
filament, like
lycra
Glass filaments,carbon
filaments,metalic wires(in
friction spinning)
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Sheath covering
Cotton either in
pure form or in
blends with
synthetic fibres.
Man made fibres
such as
polyester,polyamide,
acrylic,viscose,moda
etc

5. Production of core span yarn in
ring spinning
 Core yarn can be span in
conventional ring spinning
with little modifications.
 Wrap core wrap sandwitch
is one of the modified sing
spinning system.
 Core yarn can be span in
conventional ring spinning
with little modifications.
 Wrap core wrap sandwitch
is one of the modified sing
spinning system.
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6. Core spun yarn production by
rotor spinning
 To increase the twist efficiency, a
copper flange was soldered to the
inner end of the doffing tube. The
doffing tube was mounted on a ball
bearing, rotated by a separate drive
opposite to the rotation of the rotor
with a speed ratio of 1:9. The rotating
doffing tube inserts a false twist and
pushes twist back to the peel off point.
Twist efficiency and pre- tension of
filament are the influencing factors
in core spinning.
 To increase the twist efficiency, a
copper flange was soldered to the
inner end of the doffing tube. The
doffing tube was mounted on a ball
bearing, rotated by a separate drive
opposite to the rotation of the rotor
with a speed ratio of 1:9. The rotating
doffing tube inserts a false twist and
pushes twist back to the peel off point.
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7. :
The yarn retains almost all the strength
contributed by the core component since the
core is not twisted during spinning
The core yarns span on the rotor spinner have
the ff advantages over these spun on the ring
spinner
The yarn retains almost all the strength
contributed by the core component since the
core is not twisted during spinning
The evenness of rotor spun core yarns
are expected to be better than the
equivalent ring spun core yarns.

8.  The rotor spun core yarns are
bulkier as compared to their ring
spun counter parts. The direct
winding of core yarn on the rotor
spinner eliminate re winding process
as necessary for the ring spun core
yarns.
 The rotor spun core yarns are
bulkier as compared to their ring
spun counter parts. The direct
winding of core yarn on the rotor
spinner eliminate re winding process
as necessary for the ring spun core
yarns.

9. Core-spun yarn production by
Friction spinning system
Wide range of core
sheath ratios
Dref 3 and dref
3000 enables
production of staple
core spun yarns.
Wide range of core
sheath ratios
Dref 3 and dref
3000 enables
production of staple
core spun yarns.
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10. Production of core spun yarns in air
jet/vortex spinning
The filament core is
more commonly
,lycra or
polyurethane by
drafting it 4 to 6
times.
The out put yarn
has twist less core
wrapped by sheath
fibers.
The filament core is
more commonly
,lycra or
polyurethane by
drafting it 4 to 6
times.
The out put yarn
has twist less core
wrapped by sheath
fibers.
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11. Con..
Applications of core
spun yarn
Core spun sewing
threads of high tensile
strength
Core spun sewing
threads of high tensile
strength
stretch yarns of hosiery,
inner garments, sports
wear, medical bandages,
etc
Core spun composite
yarns (friction spun)
for technical textiles.
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13. CONVERSION OF TOW TO SLIVER
tow is a collection of
approximately 300,000 continuous
man-made fiber filaments kept in
a parallel, untwisted form. To
convert tows into a sliver, the
individual filaments must be cut
or broken collectively into staple
fibers of a specified length.
tow is a collection of
approximately 300,000 continuous
man-made fiber filaments kept in
a parallel, untwisted form. To
convert tows into a sliver, the
individual filaments must be cut
or broken collectively into staple
fibers of a specified length.
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14. Con…
A tow-to-sliver converter is a machine
which is fed by continuous filament
tow, but which delivers a staple fibre
sliver.
The stretch-breaking method can be
used for virtually any filament
thickness.
A tow-to-sliver converter is a machine
which is fed by continuous filament
tow, but which delivers a staple fibre
sliver.
The stretch-breaking method can be
used for virtually any filament
thickness.
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15. Con..
The physical properties of the fibre are
modified by stretch breaking and this
feature is exploited in the production of
bulked acrylic yarns.
The cutting method does not alter the
fiber characteristics such as strength,
extensibility, or shrinkage, and positive
control may be exercised over both the
mean and variation of fibre length.
The physical properties of the fibre are
modified by stretch breaking and this
feature is exploited in the production of
bulked acrylic yarns.
The cutting method does not alter the
fiber characteristics such as strength,
extensibility, or shrinkage, and positive
control may be exercised over both the
mean and variation of fibre length.
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16. CUTTING CONVERTERS
 A cutter converter basically comprises a feed creel, a
cutting unit, a sliver-forming section, a crimping unit,
and a sliver can delivery. As supplied by the fiber
manufacturer, the tows are within the range of 10 to 60
ktex, depending on fiber type, and are packaged in
plaited form into boxes
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ሀ

17. STRETCH-BREAKING CONVERTERS
 These converters use the idea of extending, in a
controlled manner, synthetic filaments to their
breaking strain, polyester and acrylic tow being the
principal raw materials. When heat treated, the
broken lengths of stretched filaments can be made to
readily shrink to produce a highly bulked yarn.
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ጀ

18. The influence of heater
Temperature on fiber shrinkage
Temperature
and stretch
ratio influences
shrinkage and
strength of the
yarn.
Temperature
and stretch
ratio influences
shrinkage and
strength of the
yarn.
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19. The influence of stretch ratio on fiber
shrinkage
Excesive stretch
causes
permanent break
down of some
bonds.
Excesive stretch
causes
permanent break
down of some
bonds.
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20. The influence of heater temperature
on fiber tenacity
 With in normal
range increase
temperature
increases yarn
tenacity.
 This is because of
the molecular
orientation.
 With in normal
range increase
temperature
increases yarn
tenacity.
 This is because of
the molecular
orientation.
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21. The influence of stretch ratio
on fiber tenacity
Filament
cooling takes
place befor
strech breaking.
Filament
cooling takes
place befor
strech breaking.
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22. Bulked acrylic yarn production
 A blend of pre relaxed and un relaxed fibers
is drawn and spun before being subjected to
heat treatment. This cause the un relaxed
fibers to shrink so that the yarn contracts in
length. At the same time the pre relaxed
fibers buckle and produce a considerable
increase in yarn bulk.
 Maximum yarn bulk is obtained with about
40% un relaxed fiber.
 A blend of pre relaxed and un relaxed fibers
is drawn and spun before being subjected to
heat treatment. This cause the un relaxed
fibers to shrink so that the yarn contracts in
length. At the same time the pre relaxed
fibers buckle and produce a considerable
increase in yarn bulk.
 Maximum yarn bulk is obtained with about
40% un relaxed fiber.
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23. Bulked acrylic yarn production
 A blend of pre relaxed and un
relaxed fibers is drawn and
spun before being subjected to
heat treatment. This cause the
un relaxed fibers to shrink so
that the yarn contracts in
length. At the same time the
pre relaxed fibers bucle and
produce a considerable
increase in yarn bulk.
 Maximum yarn bulk is
obtained with about 40% un
relaxed fiber
 A blend of pre relaxed and un
relaxed fibers is drawn and
spun before being subjected to
heat treatment. This cause the
un relaxed fibers to shrink so
that the yarn contracts in
length. At the same time the
pre relaxed fibers bucle and
produce a considerable
increase in yarn bulk.
 Maximum yarn bulk is
obtained with about 40% un
relaxed fiber
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24. Pre relaxation
50-60 %pre relaxed fibers blend with40-
50% un relaxed fibers.
Close control of the process is essential.
Variations greater than about 2oc can
cause deference in dye uptake which
could lead to subsequent fabric faults.
50-60 %pre relaxed fibers blend with40-
50% un relaxed fibers.
Close control of the process is essential.
Variations greater than about 2oc can
cause deference in dye uptake which
could lead to subsequent fabric faults.
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25. Final yarn shrinkage
 After spinning and yarn folding have been
completed it is usually to subject the yarn to
a heat treatment which causes the un
relaxed fibers to shrink and therefore the
bulk to develop by buckling the pre relaxed
fibers.
 For normal bulked acrylic yarns, yarn
shrinkage after spinning is usually about
22% but fiber which shrinks about 26% can
be used to produce super bulk yarns.
 After spinning and yarn folding have been
completed it is usually to subject the yarn to
a heat treatment which causes the un
relaxed fibers to shrink and therefore the
bulk to develop by buckling the pre relaxed
fibers.
 For normal bulked acrylic yarns, yarn
shrinkage after spinning is usually about
22% but fiber which shrinks about 26% can
be used to produce super bulk yarns.
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26. The end
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27. THANK
YOU
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THANK
YOU

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