What is Ginning?
Gin is the short form of the word “engine.” The process of ginning involves separating the cotton fibers from the cotton seeds. Additionally, the gin must be equipped to remove foreign matter, moisture, and other contaminants. In general, cotton lint, which is separate from seed cotton, has a staple length between 15 and 50 mm. It must be removed before the fiber can be baled from the raw cotton, which contains seeds, leaf fragments, dirt, and other materials. Approximately two-thirds of the weight of raw cotton is composed of cottonseeds. By using the cotton gin, seeds are removed.
Cotton gins were invented by Eli Whitney in 1794. The invention of Whitney was not immediately accepted, and he suffered severe financial losses. Later, other people promoted it, which played a significant role in developing the cotton industry. Cotton gin inventions also contributed to the southern United States’ dominance as a cotton producer.
Objectives of Ginning:
- In order to separate the cotton fibers from the seeds’ roots.
- In order to collect seedless cotton fiber separately from seeded cotton fiber.
- Seeds are removed from their fibers.
- To remove some of the neps and waste.
Classification of Ginning:
In the past, ginning was performed by hand or with primitive machines such as the “Foot Roller” and its improvement, the “Churka”. Currently, the cotton industry is highly automated and developed. Saw Gins have also been developed and automated. There are three types of ginning machine. They are following:
- Saw Gin
- Knife Roller Gin/Roller Gin
- Macarthy Gin.
Macarthy Gin is also three types, which are as follows:
- a. Single acting macarthy gin.
- b. Double acting macarthy gin.
- c. Double roller macarthy gin/ Double roller gin.
A saw gin is most commonly used for short and medium-length cotton. Approximately 60-100 circular disks are used to bring seed cotton into contact with the saw gin. Saw usually 12 inch diameter mounted on a horizontal shaft at ¾ inch intervals.
Main parts of the machine:
|1= Feed Lattice||6= Brush Roller|
|2= Spike Roller||7= Channel|
|3= Hopper||8= Cage|
|4= Beater||9= Pressure Roller|
|5= Saw Roller|
The saw disk are located between two grids in such a way that the saw projected between them with a narrow space. The space is too small for seed passing but sufficient for cotton to pass through it.
At first the seed cottons are feed to the hopper (3) by feed lattice (1) and spike roller (2) where a leather beater open and clean the fiber in some extent and pass the seed cotton to come in contact to the saw teeth (5). The teeth of the saw hold the seeds cotton and carried the fiber through the grids bar but the seeds are not allow to pass through it. As a result fibers are separated from the seeds. The cotton are then removed from the saw teeth with a circular brush (6) which is moving faster than the saw. The separated fibers are then Carried through a channel (7) and deposit on the surface of the case (8) by air current produced from a exhaust fan. Finally the seeds free cotton are collected from the surface of the cage with the help of pressure roller (9).
Knife roller ginning:
Roller gin which has only a limited used for long cotton fiber are separated from the seeds by drawing the fibers between a rapid revolving roller. So, that the fiber are cut off near the point of the attachment to the seed.
Main parts of the machine:
|1= Feed Table||5= Leather Roller|
|2= Hopper||6= Edged Knife|
|3= Compressing Roller||7= Stripping Brush|
|4= Knife Roller|
The usual method is to place the seed cotton on a table(1). From where it is gradually feed into the hopper (2) and then to a roller called knife roller (4) by mean of compressing roller (3). Compressing roller opens this seed and helps to move the seed cotton to a roller covered (5) by heavy leather heaving a rough outer surface by mean knife roller. A sharp edged knife (6) is placed near the revolving leather roller (5) so that the fine fiber are allow to pass but not seed. The fine fiber stick to the leather cover of the roller and are drawn between it. This removes fibers from the seed. The same seed is continuously drawn against the knife edge until all the fine fiber is removed. Then the seeds are fallen down through the grid. The seeds free cotton and then removes from the leather roller (5) by mean of stripping brush (7) and pass to delivery for further uses.
Main parts of machine:
|1= Feed Bar||5= Spring|
|2= Leather Roller||6= Grid Bar|
|3= Doctor Knife||7= Adjust Nut|
Macarthy gin is different from knife roller gin. At first seed cotton is kept on feed table, which runs into the machine slowly i. e. after entering hopper feeder it comes in contact of leather covering roller (2). Vibrating bar of feeder bar (1) Vibrates by the help of crank (4), and which falls the seed cotton on leather roller (2) and compresses doctor knife (3) by spring (5). Roller arrow rotates according to marking direction. For this reason some cotton be separated and rest seed cotton stores at the side of knife. Steel beater blade is connected with crank and rod. Due rotating crank, beater blade of rod hites seed cotton successively. Then rest seed be separated due to successive hitting and this seed is stored under position after coming through the grid bar (6). Adjusting nut (7) is used to adjust blade. bar and leather roller distance, Then seed free cotton fiber becomes separated by the help of stopping board.
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