3. What is Drafting ?
Drafting is the creation of a drawing or other graphical representation of a
building , mechanical device or other structure for the purposes of
determining how the device should be created. Drafting is used as a part of
the design and fabrication processes. Drafting can be done by hand or
using specially designed computer programs and mechanical drawings.
Drafting arrangement is the most important part of the machine. It
influences mainly evenness and strength. The following points are therefore
very important
Drafting type
Design of drafting system
Drafting settings
Selection of drafting elements like cots , apron , traveler etc.
Choice of appropriate draft
Service and maintenance
4. Types of Drafting:
There are commonly two types of drafting
system are used in ring frame
Spring loaded drafting system or
pendulum arm.
Example: SKF PK 2025 or Texparts 2035
Pneumatic drafting system: SKF PK
3025
9. RING FRAME
Introduction
The ring spinning will continue to be the most widely used
form of spinning machine in the near future because it
exhibits significant advantages in comparison with the new
spinning processes.
Following are the advantages of ring spinning frame:
It is universally applicable i.e. any material can be spun
to any required count.
It delivers a material of optimum characterisitics,
especially with regard to structure and strength.
It is simple and easy to master.
10. Operations of Ringframe
to draft the roving until the required increase is
achieved.
To impart strength to the fibre by increasing
twist.
To wind up the twisted strand (yarn) in a kym
suitable for storage, transportation and further
processing.
11.
12. Some Other Drafting Systems:
a) Ideal Draw Frame
This frame is with special metallic top and
bottom rollers with flutes on both.
13. (b) SacoLowell Versamatic
Draw Frame
In this, the frame is with ¾ drafting system
–
can process staple length from 1” to 2”.
The middle top roller doesn’t touch the
second bottom roller giving ‘Slip Drafting’.
14. (c) Zinser Draw Frame
The front bottom roller and two top rollers a
modified version of 4/4 drafting offering
tubular shaped web collector. For small
setting, the second and fourth rollers are
made movable. The draft is split-up
between the back and the front zone.
15. (d) Polar Drafting
In laxmi-rieters has usual back pair of rollers followed
by two sets of ½ drafting systems. Second and third
bottom rollers are smaller in diameter to enable closer
setting. The loading is pneumatic and can be varied
infinitely-0.75 kg per sq.cm.is normal pressure). The
rollers are arranged in the arc of a circle enabling
their movement by resetting levers. The scales are
provided so that the rollers can be set without the
need for using roller gauges.
16. (e) Whitin’s Even Draft Draw
Frame
This has universal system of 4/5 drafting.
Succeeding to usual back roller pair, there is ½
drafting system in the middle, the setting
between third and forth bottom roller being
fixed. The use of small diameter second and
third roller permits closer settings.
17. Draft Calculations:
As the material passes through the rip of the rollers, it gets pulled or
attenuated. This motion of drawing or pulling of the stock continues
throughout the spinning process. In some cases, there is attempt made
to attenuate the material; while in some other cases, a very slight
pulling action is exercised. At most of the places in the Blowroom, the
latter action is followed, while the former action is used in may
subsequent processes till the spinning of final yarn. There are thus
three type of drafts
1) Mechanical Draft(M.D)
2) Resultant or Actual Draft(A.D/R.D)
3) Tension draft
The relative speed difference in the rate of feeding and the rate
of delivery results in mechanical drafting action. Since, this is
governed by the mechanical gears or pulley diameters, it is
called Mechanical Draft.