Dry, Wet and Melt spinning

1. Fiber spinning
processes
PRESENTED BY : VIVEK S DAVE

2. Introduction
• Fiber spinning is used to make synthetic fibers for use in many industries.
• In fiber spinning a liquid polymer is extruded through small holes in a
spinneret to form thin filaments.
• Upon leaving the spinneret the filaments solidify. After solidification,
filaments can be combined to make threads and/or drawn to change the
filament‘s properties.

3. Spinning Fiber Application
• The synthetic fibers produced by solution spinning are made into
threads which are woven into fabric for everything from clothes and
carpets to airbags and wind sails.
• Sterilized synthetic fibers are used in the medical industry as sutures,
dressings, and operating room drapes, face masks, caps and
overshoes.
• Many synthetic fibers can be cut into tiny pieces called flock . Flock is
used to make velvet or suede-like materials or added to plastics or
papers for a decorative finish.

4. Fiber spinning
processes
Wet Spinning Dry Spinning Melt Spinning

5. Wet Spinning
• It is oldest process
• In wet spinning the polymer is dissolved in a non-volatile solvent.
• It is used for polymers that need to be dissolved in a solvent to be
spun.

6. • The spinneret is located in a coagulating bath that causes the fiber to precipitate
out.
• The liquid in the coagulating bath is chosen so that the solvent is readily soluble in
the liquid but the polymer is not.This will cause the polymer to precipitate out and
form the desired solid filaments.The solvent can later be recovered by treating the
wastewater in the bath.
• The drag on the filament by the viscous liquid in the coagulating bath significantly
reduces the production speed of the process.This makes wet spinning a slower
process than melt or dry spinning.

7. Fibers made with Wet Spinning
• Acrylic fiber
• Rayon fiber
• Aramid fiber
• Modacrylic fiber
• Spandex fibers

8. Wet Spinning
Advantage and Disadvantage
Advantage
Better than melt and
dry spinning for
temperature sensitive
polymers.
Disadvantage
Lower production rates
than melt or dry
spinning due to viscous
drag.
Solvent recovery is
costly.

9. Dry Spinning
• In dry spinning the polymer is dissolved in a
volatile solvent.
• Once dissolved, the polymer solution is extruded
through the spinneret which is in an enclosed
drying tower.
• The solution goes through a drying process in this
tower, where the solvent is evaporated.

10. Dry Spinning Working
• Spinning solution is filtered several times to avoid thread
defect or clogging in machine
• The solution is extruded into the drying tower through
which hot air or other gases pass.
• The concentration of the polymer increases as the solvent
evaporates, leaving a solid polymer filament behind.The
solvent is later recovered from the gas by condensation or
absorption and is then recycled.

11. Fibers made with Dry Spinning
• Acetate fiber
• Triacetate fiber
• Acrylic fiber
• Modacrylic fiber
• Polybenzimidazole fiber
• Spandex fiber
• Vinyon

12. Dry Spinning
Advantage and Disadvantage
Advantage
Better than melt
spinning for
temperature-sensitive
polymers.
Faster production rates
than melt and wet
spinning.
Disadvantage
Solvent recovery is
costly.

13. Melt Spinning
• Melt spinning is the most widely used form of fiber spinning.
• In melt spinning either molten polymer is used or polymer pellets are
melted down.
• Once the filaments are extruded they are cooled in a fluid medium
such as air, gas, or even water.

14. Melt Spinning Working
• First the molten or melted polymer is pushed
vertically downwards through the spinneret.
• When the filaments emerge from the spinneret they
are cooled by a gas, usually air, which flows either
perpendicularly across, concurrently , or counter
concurrently to the filaments.
• The filaments can then be brought together and/or
twisted together to form a thread.
• Before winding the thread on the bobbin, it is often
treated with water or a wetting agent and then a
lubricant .

15. Fibers made with Melt Spinning
• Polypropylene
• Polyester
• Nylon

16. Melt Spinning
Advantage and Disadvantage
Advantage
Ability to run at high
line speeds.
Requires no solvent
that must be recovered
later.
Disadvantage
Necessary high
temperatures may
damage some
polymers.

17. Spinneret design
• Design depends on the type of spinning and desired cross sectional
shape of the filament.
• The cross sectional shape determines different features the filament
will exhibit, such as how it will reflect light, the ability to insulate, and
how easily it shows dirt.
• Spin plates and spinnerets may have as many as 80,000 bores spaced
less than one millimeter apart.

18. Actual Fiber Spinning Machine

19. Diagrams for Exam
Wet Spinning

20. Diagrams for Exam
Dry Spinning Melt Spinning

21. “The only stupid question is the
one that goes unasked”

22. ThankYou !