The document discusses drafting in textile manufacturing. It defines drafting as reducing the mass per unit length of sliver by passing it over rotating rollers of increasing speed. The drafting process involves three stages - break draft, main draft, and tension draft. In the main draft stage, where the bulk of drafting occurs, methods like aprons and pressure bars are used to control fibers. A roving frame inserts twist and winds the roving onto bobbins after drafting. Calculations are provided to determine the ratch, or distance between rollers, based on parameters like roller diameter, winding rate, and angular velocity. Drafting results in fibers becoming more compact and chemically stable with improved strength and lower moisture absorption.

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