introduction to yarn production and processes involved in spinning

1. YARN PRODUCTION

2. Principles and machinery for yarn
production.
Spinning preparatory processes
 A spinning mill employs a number of processes to
convert the fibres into yarn or thread. These
processes contrive to clean the fibres, straighten and
align them, and then bind them together as a strand
by means of twist.

3. Spinning preparatory processes
 Bale opening.
 Removal of contamination particles
 Dust removal
 Disentanglement into fiber flocks.
 Homogenization of raw material.
 Mixing

4.  Bale opening
 Bale opening consists of opening of bales and
converting them to single fiber flocks . The
quality of opening the fibers help in better
contamination and impurities removal the more
intensely opening is done the better will be the
contamination and dust removal . By modern bale
opening systems up to 80 bales are aligned up and
flocks are separated with the help of series of
beaters and transported by air streams through
pipelines

6.  Opening and cleaning
 The main function of opening and cleaning machines are the further opening
of fiber flocks and removal of contamination particles and dust from the
cotton. Single roller or double roller opening and cleaning machines are in
practice . Working principle is based on interaction of forces of acceleration
and inertia .contaminating particles can be removed by the effect of
centrifugal force and gravity through grid bars
 The degree of cleaning (Rg) is the measure of the cleaning effect of machine
 And is defined as
 Rg = T ro - T r1.100%
T ro
T ro = trash content before cleaning
T r1= trash content after cleaning

8.  Mixing
 Mixing may take place during which batches of fibres from a number of
similar types of bale are mixed together. Mixing serves to minimise the effect
on the raw material of slight variations between the bales; this commonly
occurs with natural fibres such as cotton.

9. Carding
To separate the fibers from each other and to remove as much as possible of the
remaining impurities. This is achieved by passing the fibers between closely
spaced surfaces clothed with opposing sharp wire teeth in a process known as
carding. The fibers are assembled into a loose strand (sliver or tow) at the
conclusion of this stage.
Major objectives of carding
Removal of dirt particles .
Disentanglements of flocks into single fibers.
Parallelizing of fibers .
Mixing thoroughly
Sliver formation and delivery

11.  Action in Carding Machine :
The following actions take place in a carding machine.
 Combing action.
 Carding action.
 Stripping action.
 Doffing action.
 i. Combing action :
Combing action takes place feed roller & taken in. Here the pin directions of two surfaces are the
same. Combing is the straightening & paralleling of fibers & the removal of short fibers & impurities by
using a comb or combs which is assisted by roller & brushed.
ii. Carding action :
Carding action takes place between flat & cylinder.
In carding action,
 Directions of wire in two surfaces are opposite.
 The moving directions of roller are also opposite.
 One roller is slower & other is faster.
 So carding action is known as “Point against point” action.

12.  iii. Stripping action :

Stripping action takes place between,
a) Taker in and Cylinder &
b) Doffer and stripper.
In stripping action,
 Wire direction will be the same.
 Roller moving direction will be the same.
 One roller will be faster than another.
 So stripping action is known as “Point back point” action.
iv. Doffing action :

This action takes place between cylinder & doffer. In this place fiber is
transferred from cylinder to differ. Low speed doffer is called fiber form of
high speed cylinder & makes a condensed web for formation of sliver.

13.  Draw frames
After carding process usually there are one or two drawing passages performing following
tasks
Doubling of multiple slivers and drafting for mixing and homogenizing .
Removal of dust from slivers.
Production of homogeneously mixed slivers for example 4 cotton and 2 polyester slivers .
The drafting zone consists of 3 pairs of rollers continuous sliver is drafted
Between these and homogenized sliver is produced and stored in storage cans.

14.  Combing
 Combing is a process which is introduced into the spinning of finer and high
quality yarns from cotton. The carded materials (sliver) contain certain amount of
short fibers, neps, fine kitty and leaf particles. Short fibers are a hindrance to
spinning of finer counts where the number of fiber in the cross section of the yarn
is less. The short fibers cause thick and uneven places in the yarn length and the
yarn looks hairy. Apart from this, very short fibers do not contribute any thing to
yarn strength. Short fibers below a certain pre-determined length can be easily
separated out by using comber.
Objectives of Comber:
To remove the short fibers below a pre-selected length so that the spinner enable
to produce finer or better quality of yarn that can not be possible in carding state.
 Elimination of remaining impurities.
 Elimination of large proportion (not all) of the neps in the fiber.
 Formation of sliver having maximum possible evenness.
 To straighten the fibers.

15.  Contribution of Comber to Yarn Quality:

To improve the uniformity and strength
 Improve the spinning value of fiber.
 Reduce the neps in the yarn.
 Improve smoothness and luster of yarn.
 Produce much clear yarn.
 Improve the efficiency of the next process.
 Reduce the hairiness of the yarn.
 Improve better twist distribution in the yarn

17.  Spinning systems
 Ring spinning.
 Open end spinning .
Ring spinning
 The most popular and extensively used spinning process.
 Almost 80% of the yarn manufactured is by ring spinning
 A method that provides better and even yarn.
Ring spinning is a two step process
1 Flyer spinning frame (simplex)
In the first step the drawn sliver is pre-drafted in the flyer spinning frame while it is
also twisted slightly to prevent wrong drafts . This safety twist is not fair enough to
give the yarn strength and optimum twist level required twist for manufacturing of
fabrics the end product of this step is roving. So the next level of twist is associated
with

19.  Ring spinning machine
 In the second step the flyer roving is pulled of the flyer bobbins and
are fed to the ring spinning machine.
 First the sliver is drafted to the final yarn twisting zone via double
apron drafting unit . The essentially untwisted yarn exits the drafting
field and is twisted by the each rotation of the traveller , the yarn is
twisted once with each rotation of the cop drags the ring traveller
with it . Hence yarn is twisted with each revolution of ring traveller .

23.  Winding
 The produced yarn is in the form of small ring bobins or rotor in case of OE
spinning is further fed to the cone winding machine and yarn packages of
desired length and weight are prepared with better yarn quality by removal
of major spinning faults and waxing. The machine in practice for this purpose
is auto cone winder.