Cotton has sustained its position as the most versatile fiber in the world, even after nearly eighty centuries. None of the other fiber has such characteristics to obtain amicable results which cotton has.
Cotton has several uses and a thousand faces, it is well known for its usefulness, look, presentation and above all the comfort it gives. It generates millions of employment as it moves from yarn to final products.
Prior to reaching our wardrobes, cotton goes on an extensively hectic voyage that takes it around the world. Several players are engaged in the each phases of production. The following is a brief outline of the cotton voyage in the textile industry.
Production of Yarn
Emerging technologies have resulted massive developments in the textile industry. Machines have been modernized and now many operations are fully automated with computerized systems. The speeds of machine have been substantially increased.
At many mills the opening of cotton bales is fully automated. Lint from bales is blended together to produce a uniform fiber properties. To make sure that the automated feeding machines performs in an efficient way and the properties of fibers are uniform, computerized system dictates the bales for production and feeding as per the fiber properties.
The mixed lint is blown by air via chutes to clean, and carding machines separate and brings fibers in line to a slender web. Carding machines can process cotton at 100 pounds an hour. Following the procedure, the web of fibers that are at the front of the card is driven into funnel-shaped equipment called a Trumpet, providing rope-like thread known as sliver.
At a time, eight threads of sliver are blended in the drawing process. In recent years, drawing speeds have increased considerably, which at present is beyond 1,500 feet a minute.
Then roving frames draw/draft the slivers out finer, adds a little twist - which makes it thinner and tighter in anticipation of attaining the yarn thickness/count required for weaving or knitting fabric.
Open-end spinning with rotors, which can spin 5-6 times faster then a ring spinning machine, are getting more admiration. In this process, the yarn is made straight from sliver, eliminating roving process.
Other spinning operations have also sweep off the requirement for roving, and limitation of ring and open-end spinning that is mechanical twisting. These systems utilize compressed air currents to steady the yarn.
These operations result tightly wounding of yarns around bobbins/tubes, as well as prepares the yarn for fabric manufacturing.
Cotton fabric production begins with the preparing of the yarn for knitting or weaving.
At the loom, end-to-end yarns called the warp make the carcass like structure for the fabric. They normally require a higher degree of twisting and than filling yarns, which are integrated widthwise.
Today's mills utilize high-speed shuttleless weaving machines, which are operated at substantial speed and makes wide range of fabrics. Some holds the filling yarns through out the loom up to 2,000 meters a minute.
As of now, there are three common weaves with several variations, and cotton can be utilized in almost all.
Plain weave: In this, filling is passed under one warp yarn and over the next. This is used for percales, gingham, batistes and many other fabrics.
Twill weave: The yarns are integrated to make diagonal ridges through the fabric. Twill is used for strong fabrics, such as denim, ticking, herringbone etc.
Satin weave: Makes fabric smooth with more shine. This weave is used for making fabrics like cotton-satin.
Knitting is a process of making fabric by using needles to interlock yarn loops. Lengthwise rows are known as wales and cross rows are known as courses. There are remarkable similarities in hand knitting and machine knitting, however, there are also few differences.
In most cases, cotton is knitted on rounded machines that have series of needles attached to the frame of a rotating cylinder. As the cylinder moves, the needles start performing stitch to stitch making a tubular fabric. Its width is ruled by the cylinder size that normally varies from 9 to 60 inches in diameter.
Another type is the flat knitting machine, with a flat bed and having dozens of needles in a straight line. It makes a flat knit fabric, as same as to woven fabric. This machine performs more than one million stitches in a minute.
Cotton fabrics, directly from the loom in unfinished stages are called greige goods. To make it smooth for the preparation of dyeing and finishing, they are passed via hot copper plates and gas-fired jets to remove loose threads and lint.
Moving at speeds, which is over 200 yards a minute. The material is tattered and bleached in a non-stop process, which includes the utilizing of hydrogen peroxide. The chemicals reactions starts from crutching the fabric on the conveyor belts, which pass via steaming rooms, or huge steamed J-shaped boxes prior to the products are pull out from the beneath.
If more shine is wanted, then the products are wrapped up under pressure in a caustic soda solution and then afterwards it is stabilized. The process of mercerizing, leads the fiber to bulge lastingly, giving the fabric a silken shine and it also enhances its strength. Mercerizing can also conducted at the stage of yarn manufacture.
The normal process conducted for coloring cotton are yarn dyeing and piece dyeing. In piece dyeing process, dried fabric is continuously passed via a channel of hot-dye solution. After that the fabric is driven between rollers, which squeeze out color evenly and eliminates the glut liquid.
Yarn dyeing that is conducted prior to the fabric is knitted or woven. The process is used to roll out plaids, woven, gingham checks and other exclusive effects.
Other most usual process is package dyeing, in which yarn is slashed on perforated cylinders/packages and put on spindles in circled dyeing equipment.
Roller-printing: Design on fabric conducted on roller-print machines, which functions at speeds from 50 to 100 yards per minute. Up to ten different colors can be printed in a single operation.
A usual printing machine holds a huge padded cylinders or drums that are bounded with copper rollers. Each copper roller has its own dyeing channel and blade which removes extra dye. As per the fabric design, the number of rollers differs due to the color in the design which is imprinted on a separate roller. The cloth picks up color from the imprinted area when it is driven further into the rollers and rotating drums. Then it is sent to a heated chamber which dries the dye instantly.
Automatic screen-printing - Slower than roller printing, it has the great benefit of making larger and complicated designs, complex shadings and a variety of handcrafted designs.
Flat bed screen-printing: In this process, the design is replicated on fine net screens, one for each color. The areas in the design, which are not gone through the dye, are covered with polish or some other anti-dye coating.
Rotary screen printing: The rotary screen printing machines produces up to 3,500 yards per hour. This system includes two process, roller and screen printing, using perforated cylinders rather than flat screens. Utilizing this process, 16 colors can be printed on a single fabric.
As the term states, finishing, is the last stage in fabric manufacturing. Several finishes can be put in to the practice to textiles.
Cotton fabrics are finished in many ways than any other fabrics, changing the feel, characteristics and looks. Sometimes, number of finishes is applied to a single fabric.
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