SARMAD KHAN TS-1APRESENTATION OF MATHDRAFTING

WHAT IS THE MEANING OF DRAFT....?

STRENGTH

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

Drafting

Drafting ProcessThis process include passing of sliver over a series of rollers.The rollers rotates at specified constant angular velocities, each faster then the olderIf 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

Break DraftMain Draft Tension Draft

DraftingProcesses 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.

Break Draft :

Main Draft :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.

Tension Draft :The main object of the tension draft is to visualize better and adequate tension to the sliver.

02 4 8 10 12 1

4

10

20

30

40

50

Time (S)

Back Roller NIP

2nd Roller NIP

3rd Roller NIP

Front Roller NIP

Slow Motion Drafting :This also consist of three pairs of rollers similar

to an ordinary drafting systemIt works on exceptionally slow speedIt 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 twistBetween front roller and gathering device there is a controller which controls the speed and manage the draft

Roving Frame:

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)Roller Diameter=3cmWinding rate=120 rev/minRatch =? (distance b/w two consequence roller)Circumference = 2 pie r = d pie => 3.14x 3 = 9.42 cm or 0.0942 mW roller (Angular velocity) = 120 rev/min

= 120 pie x d /60Surface speed or roller after drafting = 0.1884 m/s

Surface speed or roller = After / Before = Draftafter drafting =0.1884/x= 8 => so, x = 0.02355 m/sVf=vi+at0.1884=0.02355+a(1) => a= 0.16m/s2S=vit+1/2at2 0.02355(1) + ½ (0.16) (1) => 0.1059 m Ratch is 0.1059 m

Impact of Drafting :

Fiber change their appearance

More closely the molecules compact together , grater the

strength

Increase chemically stability due to compactness

Lower moisture absorption

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