This presentation is about yarn drafting and its process and its type...

1. SARMAD KHAN
TS-1A
PRESENTATION OF MATH
DRAFTING

3. WHAT IS THE MEANING
OF DRAFT....?
STRENGTH

4. Drafting is the reduction of mass per
unit length of the sliver

5. This process include passing of sliver over a series
of rollers.
The rollers rotates at specified constant angular
velocities, each faster then the older
If all the draw is introduce in one step , in a single
step of feeding and take-up rollers.
This single draw can results in fiber breakage so it
is compulsory to involve more then one drawn
processes

6. Break Draft
Main Draft
Tension Draft
Processes in drafting……

7. The draft at the back zone is called
as back draft.
The main object of the break draft is
to enhance the fiber orientation
instead of drafting itself.
In the main draft execution take
place but for an optimum draft the
fiber orientation is very important.

8. Main draft is the drafting zone where
the real drafting taken place.
In here a high magnitude is taken
place.
For good fiber control many
methods are used such as aprons ,
pressure bars.
The total draft is the product of main
and break draft.

9. The main object of the tension draft
is to visualize better and adequate
tension to the sliver.

12. 0
2 4 8 10 12 14
10
20
30
40
50
Time (S)
Back
Roller
NIP
2nd
Roller
NIP
3rd
Roller
NIP
Front
Roller
NIP

13. This also consist of three pairs of rollers similar to an
ordinary drafting system
It works on exceptionally slow speed
It is known fact that slower the operation of drafting is
performed the better result.
The slowness of speed is that it may take two minutes
for the back roller to make one single revolution.
After the first drafting set the second one is gathering
device which put certain amount of FALSE twist
Between front roller and gathering device there is a
controller which controls the speed and manage the
draft

14. A roving frame is an intermediate b/w draw frame and ring frame.
It insert small amount of twist into the roving.
Wind the roving on the bobbin.

15. Time=1 sec (nip to nip)
Roller Diameter=3cm
Winding rate=120 rev/min
Ratch =? (distance b/w two consequence roller)
Circumference = 2 pie r
= d pie => 3.14x 3
= 9.42 cm or 0.0942 m
W roller (Angular velocity) = 120 rev/min
= 120 pie x d /60
Surface speed or roller
after drafting = 0.1884 m/s
Surface speed or roller = After / Before = Draft
after drafting
=0.1884/x= 8 => so, x = 0.02355 m/s
Vf=vi+at
0.1884=0.02355+a(1) => a= 0.16m/s2
S=vit+1/2at2
0.02355(1) + ½ (0.16) (1) => 0.1059 m
Ratch is 0.1059 m

16. Fiber change their appearance
More closely the molecules compact together , grater the strength
Increase chemically stability due to compactness
Lower moisture absorption

17. Bibliography:
From the lecture of Sir Mazhar Jamil
From book Modern Drafting In Cotton
Spinning (Available in Library)
From the slides of Dr.Yousuf lecturer
of BANGLADESH GREEN UNIVESITY