Drafting is the reduction of mass per
unit length of the sliver
This process include passing of sliver over a series
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 in drafting……
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.
Main draft is the drafting zone where
the real drafting taken place.
In here a high magnitude is taken
For good fiber control many
methods are used such as aprons ,
The total draft is the product of main
and break draft.
The main object of the tension draft
is to visualize better and adequate
tension to the sliver.
2 4 8 10 12 14
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
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.
Time=1 sec (nip to nip)
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
=0.1884/x= 8 => so, x = 0.02355 m/s
0.1884=0.02355+a(1) => a= 0.16m/s2
0.02355(1) + ½ (0.16) (1) => 0.1059 m
Ratch is 0.1059 m
Fiber change their appearance
More closely the molecules compact together , grater the strength
Increase chemically stability due to compactness
Lower moisture absorption
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