Cotton Ginning

Updated: Jan 8, 2021

Introduction:

In 1794 a US scientist “Eli Whitney” invented the Ginning machine. A single-roller cotton gin came into use in India by the 5th century. An improvement invented in India was the two-roller gin, known as the "churka", "charki", or "wooden-worm-worked roller". In India, about 354.5 lakh bales are produced in 2019-20. Ginning is the first mechanical process carried out for cotton and this is done only for cotton. Cotton picked from the plant known as “Kapas” which contains 66% of seeds, 33% fibers, and 1% other matter.



Definition: The process of separation of fibers from seeds is known as Ginning. These separated fibers are packed in the form of “Bales”. Cotton without seed is known as Lint. The fibers which are separated from seeds by ginning is classified into two categories 1. First, cut linters. 2. Second cut linters. The major length of fibers extracted from ginning is known as the first cut linters and rest is known as second cut linters. Each cottonseed will have about 7000 fibers on its surface, after ginning these fibers are separated and seeds are used for agriculture purposes like for cultivation or extraction of oil. Types of ginning machines: 1. Knife roller gin. 2. Macarty gin. 3. Saw gin. Knife roller Gin:


The picked cotton (kapas) is fed on to the machine through a lattice. The kapas comes into contact with the knife roller which has several knife discs on its surface and runs at 250-300 rpm. This knife cuts the fibers from the seed surface and the doctor knife will process the loosened fibers to the surface of the leather roller. Which is rotating at 120-150rpm. The separated fibers will follow the path of the leather roller and collected at the delivery end. The distance between the two rollers should be 1/3 dia of the largest seed. This type of gin is suitable for Indian cotton. Macarthy Gin:


The kapas is fed to the action of a leather roller which is rotating at 150 Rpm. The rough surface of this roller will loosen the fibers from the seed surface. The beater blade having up and down moments, which will cut the loosened fibers. The doctor knife will press the separated fibers on to the leather roller and finally, the fibers are collected at the delivery end.

Saw Gin:

The kapas is fed upon the feed lattice and then fed to the action of a spiked roller which will loosen the fibers from the seed and through them on to the saw-toothed roller. The saw-toothed roller separates the fibers completely and these fibers are stripped by the brush roller. The suction created by the fan will draw the fibers through passage and finally the fibers will be delivered in a sheet form.



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