CHAPTER 7

1 7 CHAPTER processing : from Gin to FabricGINNINGC otton gins are factories that complete the first stage ofprocessing cotton separating the lint from the seed. Gin isshort for en- gin . In Australia gins are located in cottonareas to avoid costly the gin was invented, the lint and seed were separatedby hand. It took one person a whole day to separate only halfa kilo of the lint from the cottonseed. Modern gins can separateand bale about 230,000 kilograms of cotton in one day. THE GINNING PROCESSThe seed cotton arrives at the gin in round bales or first step in the ginning process is where the cotton isvacuumed into tubes that carry it to a dryer. Cotton must beginned with a moisture level of 5%. The cotton is dried out if it is too wet or water is added if it is too dry to ensure thecorrect moisture level. Next, the cotton goes through severalstages of cleaning equipment to remove leaf trash, sticks,dirt and other foreign cleaning, the cotton is then ready for separation in the ginstand.

2 The gin stand removes the seed from the lint. In Australia,most cotton is ginned with saw gins where fast moving circularsaws grip the fibres and pull them through narrow raw fibre, now called lint, has any remaining trash removedand makes its way through another series of pipes to a presswhere it is squashed into bales under very high bale weighs 227kg. Samples are taken from each balefor classing and the bales are wrapped in stretchy white cottonfabric to protect the lint. They are now ready for transport toone of the ports for shipping into overseas being fed into the ginphoto by Andrew PattonGin is shortfor en- gin LOCATIONOF COTTONGINSC otton is pressed undervery high pressure by a bale press into balesweighing 227kg eachCotton gins like this one are mostlylocated in cottonregions to cuttransport costsTHE SEEDS MAKE UP ABOUT 55% OF THE SEED COTTON WEIGHTTHAT COMES FROM THE ARE VERY VALUABLE AND ARE USED FOR A VARIETY OFPRODUCTS SUCH AS OIL, PLASTICS,STOCK FEED, COSMETICS ANDMARGARINE.

3 THEY MIGHT ALSO BE USED AS SEEDS FOR THE NEXTCOTTON FROM GINNINGWHEN THE SEED COTTON IS PROCESSED IN THE GIN, THREE PRODUCTS RESULT COTTONSEED, LINT AND SeedLINT MAKES UP APPROXIMATELY35% OF THE SEED COTTON WEIGHT. ONCE THE LINT HAS BEEN SEPARATED IT IS COMPACTEDINTO BALES FOR EASYTRANSPORTING. THE COTTONBALES ARE THEN MOSTLYTRANSPORTED DIRECTLY TOAUSTRALIAN PORTS FOR EXPORTTO OTHER COUNTRIES TO FURTHERPROCESS (SPIN) THE Lintphoto by Pete JohnsonBales of LintTHE REMAINING 10% OF THE SEEDCOTTON IS CLASSED AS WASTEPRODUCT OR TRASH. COTTONFIBRE WASTE CAN BE USEDIN ETHANOL MANUFACTURINGOR IN PRODUCTS THAT CLEAN UPOIL SPILLS. IT CAN ALSO BE USED AS A TrashLINTTRASHTRADITIONAL CLASSING METHODThe more traditional method of testing cotton quality involves using speciallytrained classers who manually examine the cotton fibres. This testing involvesthe classer taking a sample from each bale of cotton and assessing it by:Colour (bright or dull, white or grey)Trash content (the amount of stalk, leaf or dirt)Character (whether the sample has a smooth or lumpy appearance)Staple (length of fibre)Strength of the fibresManual classers still largely determine the leaf, extraneous matter and preparationgrades of seedSoybeanRaspeseedCottonseedPeanutCOTT ONSEED VERSUS OTHER OILSEEDSW orld Oilseeds Production source: USDA5004504003503002502001501005002003/0 42004/052005/062006/072007/082008/092009 /102010/112011/122012/13 Million of tonsCottonseed is separated from thelint during the ginning the seed can be crushed foroil extraction or used for plantingfuture crops, it must be means removing any excess lint still attached to the seed.

4 These final short fibres (linters) areused to make many industrial anddomestic the linters are removed, the hull (the hardshell covering the seed) is removed. Inside thehull is the kernel the really valuable part of theseed. To produce oil, the kernels are flattenedusing rollers and then cooked at very kernels are squeezed and crushed and theoil flows out. This oil is then processed andrefined further, turning it into a light yellow,tasteless, odourless oil. Cottonseed oil is used inthe manufacture of products such as vegetableoil, margarine, soap and excess hulls and leftover kernels can beused to feed animals such as pigs, cattle COTTONSEEDAFTER THE COTTON ISGINNED, A SAMPLE ISTAKEN FROM EACH BALEAND SENT AWAY TO CLASSING ROOMS TOHAVE IT GRADED FOR ITSQUALITY. THE COTTONFIBRE IS SORTED INTODIFFERENT QUALITY-BASEDGRADES (OR CLASSES). THE HIGHER THE CLASS,THE BETTER THE QUALITYOF THE COTTON FIBRE, AND THE HIGHER THE PRICETHAT WILL BE Hammond, cotton classer, Dunavant Enterprises MEDIUM 41% LOWER 4% LOW 11% PREMIUM 24% HIGH 20%MODERN CLASSINGMETHOD - HVI TESTINGHigh Volume Instrument (HVI) testing is a machine-based method that can quickly and accuratelycheck the quality and exact value of cotton technique originated in the USA and Australiancompanies have also contributed to the world sknowledge about HVI HVI test print-out includes information relating tothe following areas:Colour grade (relating to any visible impuritiesand the degree of whiteness)Length (the price of cotton is roughlyproportional to staple length.)

5 Australian cropstypically produce 28mm ( inch) staple ifirrigated, but shorter from a dryland crop).Micronaire (the fineness of the cotton that affectshow quickly it can be spun)Trash and dust (the number of trash and dustparticles that are in the cotton)Strength (if the cotton is stronger it can be usedin smaller quantities)Length (fibre length)At the end of the classing process each 227kg baleof cotton carries a classing description. This gradewill decide whether the cotton is sold for a higher or lower price, known as premium or QUALITY OF THE AUSTRALIANCOTTON CROPG rading categories are set in eachindividual country and are revised andupdated, usually on an annual basis. In Australia, the classing grades aredetermined by the Australian CottonShippers has an enviable reputation onthe world market as a reliable supplierof very high quality cotton, and cancommand a premium price for thisreason. A recent study found newvarieties from CSIRO s cotton plantbreeding program had improved yield,HVI quality and are showing superiortextile performance Classing machinerycan accurately test for a number of cottonquality parametresSHIPPING THE COTTON TO MARKETOnce the cotton is ginned and pressed into bales it isloaded on to trucks and trains and sent to port for shipping,mostly to overseas markets.

6 Over 99% of Australia scotton is sent overseas, with only a very small spinningindustry left in Australia it s almost THE COTTON TO MARKETOnce the cotton is ginned and pressed into bales it isloaded on to trucks and trains and sent to port for shipping,mostly to overseas markets. Over 99% of Australia scotton is sent overseas, with only a very small spinningindustry left in Australia it s almost TOPRODUCE YARNOPENING, BLENDINGAND CLEANINGThe bales are laid down in a row (called alaydown), opened and blended through a range ofmachines. This ensures a consistent blend offibres. The blended fibre is then put through moremachines to loosen the fibre tufts and to removeleaf, sticks, boll parts, bark and seed fragments. Historically, cotton was spun by hand using spinning wheels thispractice is no longer used to produce commercial quantities of cottonyarns, but the method is still practiced as an artisan craft by arrives at a spinning mill in bales. Most often these millsprocess a range of different types of fibres including cotton and man-made fibres including polyester and the textile mill, the cotton is put through a number of processes,depending on the setup in the spinning mill and the desired quality of the yarn to be is the fourthlargest exporter ofcotton in the world Cotton is warehousedbefore it is shippedThe main ports for Australian cotton are in Brisbane andSydney.

7 The cotton bales are warehoused, and oncethey re sold and ready to be shipped are loaded intolarge shipping main customers for Australian cotton are spinningmills located in south east Asia China is Australia slargest buyer of Carding Machine1 CARDINGNext, the fibre is fed into a carding machine whichis often referred to as the heart of the spinningmill. The carding machine individualises, alignsand further cleans the fibres before pulling theminto a single, continuous, loose rope called Yang Textile MillsOpening Cleaning Cotton CardingDRAWINGD rawing is the process where the fibres areblended, straightened and the number of fibresreduced to achieve a desired density. It alsoimproves the evenness of the process removes any final waste from thecotton and makes it finer, stronger, smoother andmore uniform compared to carded yarns. Combedyarns are also more expensive than carded yarnsbecause there s an extra processing step andthere s more yarnCombed yarnROVINGIn preparation for ring spinning, the sliver iscondensed into a finer strand know as a roving,before it can be spun into yarn.

8 The roving framedraws out the sliver to a thickness of a fewmillimetres and inserts a small amount of twist tokeep the fibres together. This is then wound on toa bobbin in readiness for spinning are three main spinning systems usedcommercially to produce cotton:RING SPINNINGRing spinning was perfected as a process bythe end of the 19th Century. There arecurrently 213 million ring spindles installedworldwide that account for about 60% of allshort-staple yarn spinning draws out the roving andinserts a twist into the fibres by a rotatingspindle and winding the yarn onto a bobbinsimultaneously. It s a comparativelyexpensive process due to slower productionspeeds and additional SPINNING (also known as open-end spinning)This was introduced in the mid-1960s. Today, there are over 9 million rotors installedworld-wide which account for about 30% ofshort-staple yarn is fed into the machine and combed andindividualised by the opening roller. The fibresare then deposited into the rotor where aircurrent and centrifugal force deposits themalong the groove of the rotor where they areevenly distributed.

9 The fibres are twistedtogether by the spinning action of the rotor,and the yarn is continuously drawn from thecentre of the rotor. The resultant yarn is clearedof any defects and wound onto THE TEXTILE MILL, THE COTTON IS PUTTHROUGH A NUMBER OFPROCESSES, DEPENDING ONTHE SETUP IN THE SPINNINGMILL AND THE DESIREDQUALITY OF THE YARNTO BE courtesy of CSIRO and FIBREpakDrawingRing SpinningRotor Spinning AIR-JETSPINNINGThis was developed in the 1960s but wasnot commercially successful until the1980s. There are currently about 500,000airjet spinners installed is fed into the machine and is furtherdrawn out to the final count and twist isinserted by means of a rotating vortex ofhigh pressured air. The resultant yarn iscleared of any defects and wound ontopackages ready for use in fabric formation.(These spinning processes are summarised from theFIBREpak, a guide to improving Australian CottonFibre Quality)Figure 1, 2 and 3 courtesy of short Staple Manufacturing,McCreight, Feil, Bosterbaugh and Backe and FIBRE packMANUFACTURING FABRICSAFTER THE COTTON LINT HAS BEEN SPUNINTO YARN IT IS THEN WOVEN ORKNITTED INTO FabricsWeaving is the oldest method of making yarn intofabric.

10 While modern methods are more complexand much faster, the basic principle of interlacingyarns remains is done on a machine called a loom. Beforethe weaving can start, the loom needs to be set upwith warp yarn. Warp yarn runs up and down theloom. Weft yarn is then woven (or sewn) over andunder the warps from side to side. A torpedo-likeimplement at very high speeds does the weavingand can produce an almost endless variety offabrics. Some of these machines carry the yarns across the loom at rates in excess of 2,000 metersper minute! The resulting fabric is particularly are three basic weaves with numerousvariations, and cotton can be used in all of plain weave, in which the filling is alternatelypassed over one warp yarn and under the next, isused for gingham, percales, chambray, batistes andmany other twill weave, in which the yarns are interlaced toform diagonal ridges across the fabric, is used forsturdy fabrics like denim, gabardine, herringboneand satin weave, the least common of the three,produces a smooth fabric with high sheen.