Spinning preparation

Spinning
preparation
Prepared by:- Natinael Kokeb 1

Ginning

Ginning
A cotton gin is a machine that quickly and easily
separates cotton fibers from their seeds and
dust particles. Perfect ginning operation
effected without the slightest injury to either
seeds or to the fiber.
It uses a combination of a wire screen and small
wire hooks to pull the cotton through the
screen, while brushes continuously remove the
loose cotton lint to prevent jams.

Cotton Ginning Process

The seed cotton arrives at the gin in round bales or
modules.
• The first step in the ginning process is where the cotton
is vacuumed into tubes(module feeder) that carry it to
a dryer. Cotton must be ginned with a moisture level of
5%. The cotton is dried out if it is too wet or water is
added if it is too dry to ensure the correct moisture
level.
• Next, the cotton goes through several stages of
cleaning equipment to remove leaf trash, sticks, dirt
and other foreign matter.
• After cleaning, the cotton is then ready for separation
in the gin stand. The gin stand removes the seed from
the lint. Most cotton is ginned with saw gins where fast
moving circular saws grip the fibers and pull them
through narrow slots.
Cotton Ginning Process

• The raw fiber, now called lint, has any
remaining trash removed and makes its way
through another series of pipes to a
press where it is squashed into bales under
very high pressure. Each bale weighs 227kg.
• Samples are taken from each bale for classing
and the bales are wrapped in stretchy white
cotton fabric to protect the lint.
• They are now ready for transport to one of the
ports for shipping into overseas markets.

Objects of Ginning:
1. To removes the fiber from the seed.
2. To remove the neps and wastage in some
extents.
3. To collect the seed and seedless cotton fiber
separately.
4. To separate the cotton fiber from the root
position of the seeds.

Types of Ginning
1) Knife Roller Gin / Roller Gin for Indian and Pakistani cotton
I.Double roller ginning,
II.single roller ginning
III.Rotobar rotary Knife roller ginning
2) Saw Gin for American, West African, Pakistani cotton
3) Macarthy Gin for Long staple Egypt cotton
Faults of Ginning:
 Fiber are broken at the middle position so that it
becomes shorter in length.
 Crush seed remain with the cotton.
 Neps are formed in cotton.
 Remaining excessive trash in the cotton.
 Remaining fibres with seed.Prepared by:- Natinael Kokeb 8

Factors to be considered for fiber during processing:
 Main Factors
 Length
 Fineness
 Maturity
 Uniformity
 Trash Content
 Other Properties
 Pliability
 Cohesiveness
 Tensile Strength

saw gin
A cotton gin in which the lint is drawn by the
teeth of revolving circular saws through a
grating of vertical ribs too closely spaced for the
seeds to pass with the lint being removed from
the saw teeth by rotating brushes or a blast or
air.
Diagrammatic presentation of a saw gin stand.

• This process is used for American cotton, b/c
is the types of cotton in which the seeds are
not easily separated from the seeds.
• Hence to separate the cotton from the seeds it
requires a heavier beating. In this process,
heavier beating is given by the rapidly
revolving saws on the cotton seeds. The seed
cotton is fed to the feed lattice which brings
the seed cotton to the spiked roller.
• The spiked roller loosens the cotton and
passes it to the hopper region.

• In the hopper region, the seed cotton come in
contact with the saw roller which is continuously
revolving.
• As the saws are revolving continuously the teeth
of the saw gin carries the fibres forward but here
it is impossible to the seeds to follow and only
the cotton fibres pass which is being separated by
the heavier beating of rapidly revolving saws on
the seed cotton.
• The waste that includes the empty seed husks
and other broken seeds are being collected in the
grid bar. The fibres are drawn through the trunk
passage by using air current from the cage and on
further reaching the revolving cage are brought
under the pressure roller where it is delivered as
a sheet from where it is taken to the baling press.

Adjustments And Precautions
1) The bar near the saw roller could be adjusted
according to the feed received.
2) The plate near the drum could be adjusted to
prevents the seeds falling away until cleaned
thoroughly.
3) An air current from the cage should be
optimum that should suck only the fibres
because if the air current is high then it will
suck the seeds also along with the fibres and
if it is low then even the cotton fibres won’t
be sucked and the fibre under the brush
roller causes to block the machine.

Knife Roller Gin / Roller Gin
Roller gin pin-cylinder
lint cleaner.
Diagrammatic presentation of a rotary-knife
roller gin stand. Prepared by:- Natinael Kokeb 15

• This roller is used to process Indian cotton as Indian
cotton are coarser and medium. The Indian cotton is
not separated by the seeds easily. Through heavy and
continuous beating only the cotton would be separated
from the seeds.
• Heavier beating is achieved here by giving heavier
beating of the rapidly revolving knives of the roller on
the seed cotton. The construction of this roller consists
of two leather rollers on either side of a knife roller.
• On either side of the knife roller doctor’s knife is
placed. The auxiliary roller is placed on top of the knife
roller which breaks the large cluster of the cotton seed
and also provides a constant supply of the cotton to
the knife roller.

• Knife roller is arranged in such a way that
anything comes between it and contact it then
it is given a to and fro motion and striking
action is being performed.The seed cotton is
carried out to the knife roller until it comes to
contact with the leather roller.
• The leather roller has a very rough surface
because of the spirally formed saw cuts. The
cotton fibres that come to the leather roller
adhere or stick to it and are carried round past
the knife. In this only the cotton passes and it
is impossible to the seeds to follow.

• Thus the seeds will remain at the point of
contact of the doctor knife and the knife roller.
Due to the combined action of to and fro
movement, repeated quickly and because of
striking and pressure the seeds are separated
from the fibres and the seeds fall down and
are collected in the grid bar. The separated
cotton are further stripped by the means of
stripping roller.

Adjustments And Precautions
1) Care should be taken as the seeds could not go through
the dish rail and the knife roller. A small carelessness
could cause a heavy damage here by crushing a lot of
seeds.
2) According to the tenacity through which the fibres
adhere to the surface and with the help of screw the
degree of pressure of doctor’s knife over the leather
roller could be varied and adjusted.
3) The settings should be somewhat far because if the
settings are closer the seeds would be broken. The
settings should be at an optimum distance because a
large distance big and large seeds would not be acted
upon doctor’s knives and the machine could be
damaged by blocking itself.
4) The fibres are being protected as the sharp edges of the
doctor’s knife do not cut the fibres.

Bale store
• Is a room in which the cotton yarn delivered
from ginning is stored until it transported to
the first machine of blow room that is called
Uniflock.

Flow Chart of Rieter
Blowroom Line
1. Unifloc (A -11)
(Bale opener)
↓
2. Uniclean (B-12)
(Pre-cleaner)
↓
3. Unimix (B-75)
(Homogenous mixer)
↓
4. Unistore (A-78)
(Storage and feeding
machine)
↓
5. Condenser (A- 21)
↓
6. Card (C-60)
↓
7. Sliver Coiler (CBA -4)

Introduction to Blowroom
• Blow room is the first step of yarn production
in spinning mills. A section in which
compressed bales are opened, cleaned and
blending or mixing to form uniforms lap of
specific length is called Blow room section.
The cleaning efficiency of blow room is 40 to
70%. This is the first section of spinning line
for spinning of cotton yarn.

Functions of blow room
1. Opening the compressed bales of fiber and
making the cotton tuft a small size as far as
possible.
2. Detecting the metal objects and fire in fiber
3. Cleaning the fiber by removing the dust, dirt,
broken seeds etc. and other foreign materials from
the fibers.
4. Mixing and blending of different classes or grades
of fibers
5. Removing foreign fibers and plastic
contaminations
6. Uniform feeding to the next stage.

Machine used in Blowroom
Unifloc
Magnetic
metal detector
Uniclean
Color detector Unistore Unimix
Chute feeder

Basic Parameters to be Considered in
Blowroom
• No. of opening machine
• Types of beater
• Beater speed
• Production rate of individual machine
• Fiber micronaire
• Size of the flocks in the feed
• Type of grid and grid setting
• Position of the machine in the sequence
• Amount of trash in the material
• Temperature and relative humidity in the blow room

Principle of Opening and Cleaning
• Opening: Opening is the first operation in the
blow room carried out to the stage of Flocks. ln
the-blow room and to the stage of individual
fibers in the cards.
In the stages of the opening, machines with an
opening function have the task of separating
clumps of fiber into smaller ones. The sizes of the
clumps, and of the teeth that deal with them, are
progressively reduced. In general terms, grasping
clumps of fibers with sets of teeth and dragging
the clumps across another set of teeth or grids
perform the opening function.

• Cleaning: With cotton, there are often seed
coat fragments attached to them. It is difficult
to remove some of the extraneous matter
without vigorous mechanical action and
without adequate opening. Every time a
clump of fibers is divided, a new surface is
exposed from which it is relatively easy to
remove the loose unwanted matter (trash).

Working Principle of
Unifloc/BDT/Automatic Bale Opener
• In this zone, basic function is to open the fiber from the
bale where fibers are at very compressed and disoriented
state. The opening device has to penetrate into the bale
and pick up the tuft of fiber during releasing from different
bales simultaneously. The size of fiber package is converted
from 200 kg to 10 gm/tuft in this zone. The machine moves
to cover maximum bales. Generally, roller with toothed disc
is used for opening device. No beating action but picking is
performed here.
• As shown in figure, rotating opening rollers fitted with
toothed discs are made to traverse a line of preassembled
cotton bales, the toothed discs plucking tufts from each
bale as they move from bale to bale. The toothed discs give
a gentle opening to prevent or minimize the fiber breakage
while producing smaller tuft sizes at higher production
rates than the mixing bale opener.

A further feature of the A 12 is the innovative bale scanning. The
take-off unit determines the different heights of the bales by
means of scanning force measurement and quickly equals them
out. Through this uniform take-off, the machine achieves its
highest possible production rate in the shortest time.
Inside the take-off unit, there is a roller with numerous teeth
which gently opens the bales into very small tufts. This is the basis
for effective cleaning and dedusting in the subsequent blowroom
process. A remarkable feature is that the A 12 is extremely
efficient, even with these very small tufts. In the A 12, motors and
servo-units of the latest technology are used and this also enables
the UNIfloc to recover energy during production. The brake
power which is generated during reversal of the take-off roller is
fed back into the electricity grid. (GK)
RIETER A 12 UNIFLOC AUTOMATIC BALE OPENER

The UNIfloc is designed for an output of up to
1 200 kg/h (card sliver). Depending on the
selected machine length, the bale laydown
covers a length of 7.2 to 47.2 meters. Work-
intensive manual equalizing of the bale height
is no longer required thanks to automatic bale
profiling.
Bale opening into microtufts provides the basis
for the effective cleaning and dust extraction
by the subsequent machines.

Machine build up
Conveyer
belt(matterial
transport)
drive
Carriage drive 180° tower
rotation driving

Material take-off roller drive
Material take-
off(double patented
teeth) roller
Personal safety sensors
Up and down movement spindle drive
wayofopenedmaterial
totake-offroller

Working Principle of Metal & fire
detector/ SP-EM
• The electronic Metal Separator SP-EM helps to
protect the cleaners and cards from metal
parts at the interface between bale work-off
and mixers/cleaners. Since, in the process, the
material transport is performed by the
downstream machine, it is free of exhaust air
and requires no filter capacity. In order to
reduce fire damage, the machine is equipped
with sensors. They are connected to the
installation control.

Uniclean

• It is a coarse cleaning machine. The small tufts
of uniflock machine are fed in this machine.
• There are opening roller consists with many
spikes helps to opening the tuft of fiber and
with combination of grid bar fiber is cleaned
here. Trash, dust and foreign material of
cotton fiber are separated by this machine.
• Cleaning is performed without nipping and is
therefore very gentle to the fibers and at the
same time efficient. This ensures a high level
of raw material utilization. The output of the
machine is up to 1200 kg/h to be achieved.

Cleaningcylinder
Cleaninggrid
Airlock cylinder
Airlock cylinder
Wasteremovingduct
Technical data
Diameter of cylinder: 700~800 mm
Speed of cylinder : 400~800 rpm
Grid bar setting: 2.5~3.5 mm

Unimix machine
Technical data
Storage volume per chamber:
1.4~2.6
Storage capacity per chamber:
40~80 kg
Speed of opening roller:
1000~1200 rpm

Figure above and below
(figure below)

Rieter B70
unimix

Rieter A78 unistore feeding machine

Thank
you!!

Spinning preparation

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