different drawing methods employe in spinning technique

1. Different Drawing
Methods
Submitted by: Pankaj Kumar Das
B.Tech Polymer science
(1308023)

2. Drawing
• It is defined as a process of stretching spun
fiber on a roller at a specific draw ratio to
significantly align the fiber molecules result in
a higher degree of crystalinity and enhance
physical properties.

3. Why do we need “Drawing”?
• To develop the fiber strength, polymer molecules in both the
crystalline and the non-crystalline regions are further oriented by
elongating the fiber between two rolls at different speeds.
• Higher draw ratio generally leads to higher molecular orientation
and thus higher fiber strength.
• Mostly, increasing the drawing speed (higher elongation rate),
drawing at a temperature lower than appropriate, or increasing the
orientation of the feeder yarn from the spinning process decreases
the fiber uniformity and quality.
• Therefore, spinning and drawing are best operated as an integral
process to control the fiber morphology, physical properties, and
end-uses.

4. Drawing machine
• Drawing is carried out by simply stretching the filament yarn between
two sets of rollers.
• The drawing occurs between feed rollers and take-up rollers (Draw
rollers) at room temperature or at an elevated temperature by
providing a heater plate.
• The drawn material is given a small twist and is wound on a bobbin.
• The path of the yarn undergoing drawing is regulated by proving guide
pins or alternately placing the feed and take-up (drawing) rollers
perpendicular to each other.
• An idler roller at an angle is provided with each roller set (i.e. feed or
draw) to allow the yarn to be wound in multiple loops separately on
each on these rollers. This gives a better grip to the yarn and the yarn
does not slip easily under drawing tension.

6. PROCESS INTEGRATION
• To increase process efficiency and reduce production
costs, an industrial effort has succeeded in integrating
the spinning and drawing processes.
• Therefore, there are now three different types of
spinning process arrangements. Each of these processes
gives a different set of yarn properties and morphology.
I. Separate spinning and drawing: a two-step process
II. Stack-draw process: a one-step process
III. Spin-draw process: a one-step process

7. Separate spinning and drawing
• This method is most widely used for the production of various
yarn types.
• The take-up speed is generally around 1000m/min to make
‘‘undrawn’’ yarn of low orientation.
• The undrawn yarn is ‘‘lagged’’ in storage for 4–12 h and then
drawn at about 3:1 draw ratio to develop the fiber strength.
• The process of this type, yields a fully drawn yarn (FDY).
• Additional twisting step to provide the filament bundle
cohesiveness is generally followed in the same process.
• Thus, the process is also called a draw-twist process.

8. Stack-draw process
• The take-up speed of this one-step process is
greater than 3000m/min.
• The product is known as the partially oriented
yarn (POY).
• The combination of drawing and textile finishing
seems suited particularly for the production of
POY at high spinning speeds.

10. Spin-draw process
• The take-up speed of this process ranges from
600 to 3000m/min, coupled with immediate
drawing on the panel.
• The resulting product is a fully drawn yarn.

12. Draw-Twisting
• Polyamide filaments produced in high-speed operations
that do not combine spinning and drawing processes must
be subjected to a subsequent draw-twisting process to
develop more useful properties.
• Since this process is performed in the solid state, the
resulting orientation is mainly controlled by the draw
(deformation) ratio and is less affected by relaxation factors
(molecular motions).
• Thus the drawing rate and temperature in the draw-
twisting process are of less importance than they are in the
spin-draw process.

13. Spinning–Drawing–Texturing
• A one-step spinning–drawing–texturing process for carpet
and other applications.
• In this process, the yarn is generally spun at a take-up
speed of about 2000m/min, immediately drawn on panel at
a draw ratio from 1.1 to 2.5, and passed through a texturing
device to develop a crimped fiber.
• The crimped fiber will continue onto a perforated drum to
be cooled before it is wound up on a package.
• Alternatively, an undrawn yarn spun earlier can be used as
a feeder yarn to be drawn and textured as above.

14. References
• https://books.google.co.in/books?id=XIIrBgAAQBAJ&p
g=PA82&lpg=PA82&dq=Separate+spinning+and+drawi
ng:+a+two-
step+process&source=bl&ots=a1ij1TnNQA&sig=5iuRD7
c2jYR21KSxC7SiKOCsKmY&hl=en&sa=X&ved=0ahUKEwi
D8qmFgZzQAhXBNI8KHYVhD90Q6AEIITAB#v=onepage
&q=Separate%20spinning%20and%20drawing%3A%20
a%20two-step%20process&f=false
• Handbook_of_Fiber_Chemistry.