Textile manufacturing
Textile manufacturing or textile engineering is a major industry. It is largely based on the conversion of fibre into yarn, then yarn into fabric. These are then dyed or printed, fabricated into cloth which is then converted into useful goods such as clothing, household items, upholstery and various industrial products.
Different types of fibres are used to produce yarn. Cotton remains the most widely used and common natural fiber making up 90% of all-natural fibers used in the textile industry. People often use cotton clothing and accessories because of comfort, not limited to different weathers. There are many variable processes available at the spinning and fabric-forming stages coupled with the complexities of the finishing and colouration processes to the production of a wide range of products.
History
Textile manufacturing in the modern era is an evolved form of the art and craft industries. Until the 18th and 19th centuries, the textile industry was a household work. It became mechanised in the 18th and 19th centuries, and has continued to develop through science and technology since the twentieth century. Specifically, ancient civilizations in India, Egypt, China, sub-Saharan Africa, Eurasia, South America, and North and East Africa all had some forms of textile production. The first book about textile manufacturing is considered to be 'A Treatise on the Art of Weaving' by John Murphy.Processing of cotton
Cotton is the world's most important natural fibre. In the year 2007, the global yield was 25 million tons from 35 million hectares cultivated in more than 50 countries.There are six stages to the manufacturing of cotton textiles:
- [|Cultivating and Harvesting]
- [|Preparatory Processes]
- [|Spinning]
- [|Weaving] or [|Knitting]
- [|Finishing]
- [|Marketing]
Cultivating and harvesting
Ginning
The seed cotton goes into a cotton gin. The cotton gin separates seeds and removes the "trash" from the fibre. In a saw gin, circular saws grab the fibre and pull it through a grating that is too narrow for the seeds to pass. A roller gin is used with longer-staple cotton. Here, a leather roller captures the cotton. A knife blade, set close to the roller, detaches the seeds by drawing them through teeth in circular saws and revolving brushes which clean them away. The ginned cotton fibre, known as lint, is then compressed into bales which are about 1.5 m tall and weigh almost 220 kg. Only 33% of the crop is usable lint. Commercial cotton is graded and priced according to its quality; this broadly relates to the average length of the staple and the variety of the plant. Longer-staple cotton is called Egyptian, medium staple is called American upland, and short staple is called Indian. The cotton seed is pressed into cooking oil. The husks and meal are processed into animal feed, and the stems into paper.Preparatory processes – preparation of yarn
Ginning, bale-making and transportation
Ginning, bale-making and transportation are done in the country of origin.Opening and cleaning
Cotton is shipped to mills in large 500-pound bales. When the cotton comes out of a bale, it is all packed together and still contains vegetable matter. The bale is broken open using a machine with large spikes, called an opener. To fluff up the cotton and remove the vegetable matter, the cotton is sent through a picker or a similar machine. In a picker, the cotton is beaten with a beater bar to loosen it up. It is then fed through various rollers, which serve to remove the vegetable matter. The cotton, aided by fans, then collects on a screen and gets fed through more rollers where it emerges as a continuous soft fleecy sheet, known as a lap.Blending, mixing and scutching
refers to the process of cleaning cotton of its seeds and other impurities. The first scutching machine was invented in 1797, but did not come into further mainstream use until after 1808 or 1809, when it was introduced and used in Manchester, England. By 1816, it had become generally adopted. The scutching machine worked by passing the cotton through a pair of rollers, and then striking it with iron or steel bars called beater bars or beaters. The beaters, which turn very quickly, strike the cotton hard and knock the seeds out. This process is done over a series of parallel bars so as to allow the seeds to fall through. At the same time, air is blown across the bars, which carries the cotton into a cotton chamber.Carding
In the carding process, the fibres are separated and then assembled into a loose strand. The cotton comes off of the picking machine in laps, and is then taken to carding machines. The carders line up the fibres neatly to make them easier to spin. The carding machine consists mainly of one big roller with smaller ones surrounding it. All of the rollers are covered in small teeth, and as the cotton is moved forwards, the teeth get finer. The cotton leaves the carding machine in the form of a sliver: a large rope of fibres. In a wider sense, carding can refer to these four processes:- Willowing: loosening the fibres
- Lapping: removing the dust to create a flat sheet or lap of cotton
- Carding: combing the tangled lap into a thick rope of 1/2 inch in diameter, a sliver
- Drawing: where a drawing frame combines 4 slivers into one, repeated for increased quality
Several slivers are combined. Each sliver will have thin and thick spots, and by combining several slivers together, a more consistent size can be reached. Since combining several slivers produces a very thick rope of cotton fibres, the slivers are separated into rovings. Generally speaking, for machine processing, a roving is about the width of a pencil. These rovings are then what are used in the spinning process.
Spinning – yarn manufacture
Spinning
Most spinning today is done using break, or open-end spinning. This is a technique where the fibres are blown by air into a rotating drum, where they attach themselves to the tail of formed yarn that is continually being drawn out of the chamber. Other methods of break spinning use needles and electrostatic forces. This method has replaced the older methods of ring and mule spinning. It is also easily adapted for artificial fibres.The spinning machines takes the roving, thins it and twists it, creating yarn which it winds onto a bobbin.
In mule spinning the roving is pulled off a bobbin and fed through rollers, which are feeding at several different speeds. This thins the roving at a consistent rate. If the roving was not a consistent size, then this step could cause a break in the yarn, or jam the machine. The yarn is twisted through the spinning of the bobbin as the carriage moves out, and is rolled onto a cylinder called a spindle, which then produces a cone-shaped bundle of fibres known as a "cop", as the carriage returns. Mule spinning produces a finer thread than ring spinning.
The mule was an intermittent process, as the frame advanced and returned a distance of five feet. It was the descendant of the 1779 Crompton device. It produces a softer, less twisted thread that was favoured for fine fabrics and wefts.
The ring was a descendant of the Arkwright Water frame of 1769. It was a continuous process, the yarn was coarser, had a greater twist and was stronger, thus suitable for use as warp thread. Ring spinning is slow due to the distance the thread must pass around the ring.
Sewing thread was made of several threads twisted together, or doubled.
Checking
This is the process where each of the bobbins is rewound to give a tighter bobbin.Folding and twisting
Plying is done by pulling yarn from two or more bobbins and twisting it together, in a direction opposite to the one it was spun in. Depending on the weight desired, the cotton may or may not be plied, and the number of strands twisted together varies.Gassing
Gassing is the process of passing yarn very rapidly through a series of Bunsen gas flames in a gassing frame, to burn off the projecting fibres and to make the thread round and smooth and bright. Only the better qualities of yarn are gassed, like the kinds used for voiles, poplins, venetians, gabardines, Egyptian cottons, etc. The thread loses around 5-8% of its weight if it's gassed. The gassed yarn is darker in shade afterwards, but should not be scorched.Measurements
- Cotton Counts: Refers to the thickness of the cotton yarn where 840 yards of yarns weighs. 10-count cotton means that of yarn weighs. This is coarser than 40-count cotton where 40x840 yards are needed. In the United Kingdom, counts from 10 to 40 are coarse, 40 to 80 are medium counts and above 80 is a fine count. In the United States ones, counts up to the 20s are coarse counts.
- Hank: A length of 7 leas or 840 yards
- Thread: A length of 54 in
- Bundle: Usually 10 lb
- Lea: A length of 80 threads or 120 yards
- Denier: this is an alternative method. It is defined as a number that is equivalent to the weight in grams of 9000m of a single yarn. 15 denier is finer than 30 denier.
- Tex: is the weight in grams of 1 km of yarn.