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UNIT-1
Ginning
1B.TECH TEXTILE TECHNOLOGY 2nd YEAR 1st SEM
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The primary object of the ginning consists in
separating the fibres from the seed
A Perfect ginning operation would bePerformed if the separation of fibres
from seed was effected without the slightest
injury to either seeds or to the fiber.
2nd YEAR 1st SEM 2B.TECH TEXTILE TECHNOLOGY
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The cotton first goes through
dryers to reduce moisture
content and then through
cleaning equipment to removeforeign matter.
These operations facilitate
processing and improve fiberquality.
2nd YEAR 1st SEM 3B.TECH TEXTILE TECHNOLOGY
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A typical gin will process about 12 bales per
hour, while some of todays more modern gins
may process as many as 60 bales an hour.
2nd YEAR 1st SEM 4B.TECH TEXTILE TECHNOLOGY
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Previous to the introduction of Modern
Machinery, ginning was performed by hand or
by machines of a primitive character such as
the "Foot Roller" and its improvement the"Churka".
As the cotton industry developed, greater
production than these were capable of was
necessary, and machines driven by powerwere introduced.
2nd YEAR 1st SEM 5B.TECH TEXTILE TECHNOLOGY
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2nd YEAR 1st SEM 6B.TECH TEXTILE TECHNOLOGY
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2nd YEAR 1st SEM 7B.TECH TEXTILE TECHNOLOGY
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2nd YEAR 1st SEM 8B.TECH TEXTILE TECHNOLOGY
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2nd YEAR 1st SEM 9B.TECH TEXTILE TECHNOLOGY
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Numerous forms of gins have been tried, but
at the present time only three are used to
any large extent. They are
1. KNIFE ROLLER GIN 2. SAW GIN
3. THREE TYPES OF MACARTHY GIN
I. Single acting macarthy gin.
ii. Double acting macarthy gin
iii. Double roller macarthy gin.
2nd YEAR 1st SEM 10B.TECH TEXTILE TECHNOLOGY
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2nd YEAR 1st SEM 11B.TECH TEXTILE TECHNOLOGY
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2nd YEAR 1st SEM 12B.TECH TEXTILE TECHNOLOGY
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The ginning roller is the most important and
expensive component in the gin stand.
Roller-covering material is made from 13 layers
of plain-woven cotton fabric cemented together
with a white rubber compound.
The fabric lays on the bias so that neither the
warp or fill yarn are parallel to the direction of
cutting; this prevents the material from
unraveling from the roller surface.
The roller material mounts on to the roller core
with the cut edges of the fabric layers serving as
the ginning surface.
2nd YEAR 1st SEM 13B.TECH TEXTILE TECHNOLOGY
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Rotary-knife roller gin stands separate fiber
from seed by using the frictional forces
between a moving roller and fixed
stationary-knife surface.
During normal ginning, the roller-to-fiber
force is greater than the stationary knife-to
fiber force; therefore, the fiber sticks to the
roller surface and slips on the stationaryknife surface.
2nd YEAR 1st SEM 14B.TECH TEXTILE TECHNOLOGY
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Cotton is ginned as fibers adhered to the
roller surface slip under the stationary knife
which holds the seed.
Each stroke of the rotary knife clears thestationary knife edge of accumulated seed
cotton and ginned and partially-ginned seed.
Partially ginned seed are either pulled back
to the stationary knife and completelyginned or swept along with the seed and
carryover and later reclaimed.
2nd YEAR 1st SEM 15B.TECH TEXTILE TECHNOLOGY
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2nd YEAR 1st SEM 16B.TECH TEXTILE TECHNOLOGY
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The seed cotton is placed in bulk on the
table.
By means of the reciprocating motion of the
table by the crank arrangement, the seedcotton comes into contact with knife roller
(formed of a number of knife discs).
Auxiliary roller breaks the large cluster of
seed cotton and maintains a constant supplyof cotton to knife roller.
2nd YEAR 1st SEM 17B.TECH TEXTILE TECHNOLOGY
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Knife portion being arranged in such amanner that anything coming into contactwith it is given a reciprocal or to and fromotion as well as being subject to a striking
action due to its revolution. The seed cotton is carried forward in the
direction of knife roller's motion until it isbrought into touch with leather roller.
This roller, which has a much roughenedsurface, due spirally-formed saw cuts Haspressing against, it by means of springand steel doctor Knife.
2nd YEAR 1st SEM 18B.TECH TEXTILE TECHNOLOGY
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The cotton fibres brought into contact with
the leather adhere to it, and are carried
round past the knife.
It is impossible for the seeds to follow. So,seeds will remain at the point of contact of
the doctor knife and leather roller, with the
fibres still connected with it.
The essential feature of this gin now comesinto play.
2nd YEAR 1st SEM 19B.TECH TEXTILE TECHNOLOGY
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The knife roller is so set as to act upon,
these adhering seeds, and it gives to them a
gentle to and fro motion, repeated very
quickly 'and at the same time a slight striking
action or pressure also repeated quickly.
The combined action soon causes the seeds
to separate from the fibres and to fall down
through the grid to floor.
2nd YEAR 1st SEM 20B.TECH TEXTILE TECHNOLOGY
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The freed fiber passing forward is stripped
from the roller by some arrangement of the
stripping board.
The seed cotton not taken up by one leatherroller (on the right of the figure) is brought
round into contact with another Leather
roller where same process as described
above is gone through and to which the sameparts equally apply.
2nd YEAR 1st SEM 21B.TECH TEXTILE TECHNOLOGY
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2nd YEAR 1st SEM 22B.TECH TEXTILE TECHNOLOGY
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2nd YEAR 1st SEM 23B.TECH TEXTILE TECHNOLOGY
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2nd YEAR 1st SEM 24B.TECH TEXTILE TECHNOLOGY
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The seed cotton is placed on the table. By
means of the reciprocating motion of the
table by the crank arrangement, the seed
cotton comes into contact with the revolving
leather covered roller.
Some cotton fibres are carried in the
direction of leather roller, but seed cottons
are arrested by the doctor knife.
2nd YEAR 1st SEM 25B.TECH TEXTILE TECHNOLOGY
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A steel beater blade is connected by means of a
connecting rod, with a crank on the driving
shaft.
Due to the seeds being acted upon by the rapid
reciprocating motion given to the beater blade
by the crank, the seeds are separated from
fibres.
Ginned cotton fibres are carried onward in the
direction of leather roller, stripping board stripthe fibres from the leather roller and empty
seeds are thrown into grid, through which they
pass into suitable receptacle.
2nd YEAR 1st SEM 26B.TECH TEXTILE TECHNOLOGY
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The vertical movement of the beater bladeshould be 3/8 inch above the doctor knife.
Sharp edge of the doctor knife should not cutthe fibres.
The degree of pressure of the doctor knife
upon the leather roller can be varied accordingto the tenacity with which the fibres adhere tothe seeds. This is done by adjusting the springand thumb screws.
The pressure of the doctor knife
and distance between leather roller anddoctor knife should be in such a way that noseed will be allowed to pass in the direct ion ofleather roller.
2nd YEAR 1st SEM 27B.TECH TEXTILE TECHNOLOGY
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2nd YEAR 1st SEM 28B.TECH TEXTILE TECHNOLOGY
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2nd YEAR 1st SEM 29B.TECH TEXTILE TECHNOLOGY
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There are two leather roller and a doctor
knives is pressed against each leather roller.
The beater knives act from above, and are
given a reciprocating motion from a crank.Crank pin slide in a slot of arm carried by a
vibrating shaft.
Beater blades are fixed on arms projecting
from vibrating shaft Also grid and fingers arefixed on vibrating shaft.
2nd YEAR 1st SEM 30B.TECH TEXTILE TECHNOLOGY
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Seed cotton is fed into hopper -spaces.
The crank movement lowers this cotton intocontact with leather roller in one side and raises itaway from the roller on other side.
When the cotton comes into contact with leather
roller, some cotton fibres are carried in the directionof leather roller but seed cottons are arrested by thedoctor knife due to the seeds being acted upon by-the rapid reciprocating motion given to the beaterblade by crank, the seeds are separated from fibres.Ginned cotton fibres are carried forward in the
direction of leather roller. Empty seeds are thrown into grid.
As the grid lowers, the space in it permit the fixedfinger to pass between them, and so shake the seedto cause them to fall out readily.
2nd YEAR 1st SEM 31B.TECH TEXTILE TECHNOLOGY
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2nd YEAR 1st SEM 32B.TECH TEXTILE TECHNOLOGY
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The seed cotton is fed upon the lattice and
carried forward to the spiked roller, which
loosens the cotton and throw;
it into the hopper.
In hopper, the seed cotton comes into
contact with rapidly revolving saw
roller. Approximately 70 saws are threaded
on a shaft.
2nd YEAR 1st SEM 33B.TECH TEXTILE TECHNOLOGY
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As the saws revolve, the teeth carry the
fibres forward, but it is impossible for the
seeds to follow and also, due to the heavier
beating of the rapidly revolving saws on the
seed cotton, the fibres are separated from
seed and taken round until the brush strips
the fibre from the teeth.
Empty seeds husks and other broken seedsare thrown into grid, through which they
pass into suitable receptacle.
2nd YEAR 1st SEM 34B.TECH TEXTILE TECHNOLOGY
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An air current from the cage draw the fibres
along the trunk passage, and on reaching therevolving cage are brought under the
pressure roller and delivered as a sheet,
from which it is taken to the baling press.
2nd YEAR 1st SEM 35B.TECH TEXTILE TECHNOLOGY
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SETTINGS:
An air current from cage should be optimum
to 'suck only fibres.
If air current is high - it will "suck seed also withfibres.
If air current is low - fibre accumulation under
brush roller causes to block the machine.
2nd YEAR 1st SEM 36B.TECH TEXTILE TECHNOLOGY
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Saw gin is suitable to process American
cotton and wherever American cotton is
grown, such as west Africa- India, Ceylon
etc.
These cottons are oily type in which the
fibres are not too easily separated from the
seeds, so heavier beating on seed is required
to separate the fibres. This is achieved in this gin by giving heavier
beating of the rapidly revolving saws on the
seed cotton.
2nd YEAR 1st SEM 37B.TECH TEXTILE TECHNOLOGY
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CAUSES FOR BROKEN SEEDS:
1. Improper setting between knife roller and dish
rail.
2. Improper setting between knife roller and
leather roller.
3. Improper setting between beater blade and
doctor knife in McCarthy gin
4. Improper setting of the adjustable plate, Bars
in saw gin.
2nd YEAR 1st SEM 38B.TECH TEXTILE TECHNOLOGY
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CAUSES FOR FIBRE DAMAGES:
1. Too much pressure of doctor knife on leather
roller.
2. Knives of the knife rollers are too sharp.
3. Sharp edges of the saw discs.
4. Improper setting between doctor knife and
leather roller.
5. Too close setting .between knife roller and dish
rail.
2nd YEAR 1st SEM 39B.TECH TEXTILE TECHNOLOGY
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CAUSES FOR NEPS FORMATION:
1. High speed of knife roller and saw roller.
2. Blunt edges of knife and saw disc.
To avoid defective ginning,
(I) various settings in the gin should be proper
(ii) speeds of the rollers should be in correct
range (iii) condition of the knife disc and saw disc
should not too sharp or too blunt and it should be
optimum.
2nd YEAR 1st SEM 40B.TECH TEXTILE TECHNOLOGY
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2nd YEAR 1st SEM 41B.TECH TEXTILE TECHNOLOGY
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