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Yarn spinning systemsYarn count Yarn

Generic tem for a continuous strand of textile fibres , filaments or material in a form suitable for knitting, weaving or otherwise intertwining to form a textile fabric Or A product of substantial length and relatively small cross-section consisting of fibers and/or filaments, with or without twist.

Types of yarns There are two types of yarns Spun yarns ( short-staple yarns)Filament yarnsThese can further be classified according to their method of construction: Compound yarns (covered and core-spun)Fancy yarnsSimple yarns

(3) Spun Yarn -- A staple-spun yarn is a linear assembly of staple fibers, held together, usually by the insertion of twist, to form a continuous strand, small in cross section but not of any specified length; it is used for interlacing in process such as knitting, weaving, and sewing.

When staple fibers are twisted together by the process of spinning, the product may be referred to as spun yarns.Linear density/yarn countYarn count is a numerical expression, which defines yarn fineness. Spun Yarns are only roughly circular in cross-section and irregularity in thickness is unavoidableOne of the most important requirements for a spinner is to maintain the average count and count variation within controlYarn Count is number indicating the weight per unit length or the length per unit weight of yarnused as an alternative measure of actual fineness or thickness of yarnstwo yarn count systems are commonly useddirect systemindirect systemDirect system of Yarn CountYarn count is the mass of a unit length of yarnLength of the yarn is constant and weight variesGeneral formula which applies to all directs systems can be written as follows:

Tex (g/1000m)

Defined as weight in grams of 1000m length of yarnAs the number increases the yarn gets thickerApplicable for all types of fibres , yarns

Denier Weight in grams of 9000m length of yarnAs the yarn number increases , the yarn gets thicker or coarserMainly used for filament yarnsDecitexDefined as weight in grams of 10 000meters length of yarnYarn gets thicker or coarser with increase in yarn numberIndirect yarn numberingIn this system fineness is measured in length per unit weight Weight is constant and length varies

Cotton count- NeDefined as number of hanks (840 yds ) present in 1 lb of yarn. As the yarn number increases, yarn gets thinner or finerMainly used for cotton spun yarns, silk, synthetic spun yarnsE.g. 40 Ne Means 40 hanks of 840yards give us 1pound i.e.40x840 yards length weigh one pound

Metric count- NmDefined as the number of hanks of 1000 meters present in 1 kg of yarn. As the yarn number increases, the yarn gets thinner or finerMainly used for woolen and worsted yarns

Conversions

End uses of yarn counts

On one cone there are 9800 m yarns which weigh 490 gm. What is the English count of this yarn?

If one thousand meters of yarn weigh 20 grams or one hundred meters of the yarn weigh 2 gramsSpinning SystemsShort staple system - Cotton system CardedCombed cotton/cotton blendsLong staple system Worsted system Woolen system woolen yarnsCotton spinning The cotton spinning process is generally used for cotton and man-made staple fibresCarded and combed reflect the degree to which the fibres lie parallel to the yarn axis Carded yarns contain fewer aligned fibres than combed yarnsFibres in Combed yarns are more aligned and longer

The wool spinning process is mainly used to produce wool and wool-blend yarns. A distinction is made between the worsted and woollen process. In worsted spinning, higher-quality and longer fibres are processed and the result is a fine yarn which is used to produce worsted fabric. In the woollen spinning system, shorter fibres are processedWoollen system In the worsted process the fibres are paralleled in a combing machine and are then drawn and spun. In the woollen system the fibres are only carded and then spun. The resulting yarn is then twisted (if required) and finally prepared for the subsequent treatments (dyeing, weaving, tufting, etc) through an operation called winding.Worsted can also be used to describe 100% manufactured fibre spun yarns e.g. 100 worsted acrylic yarns

Short staple spinning systemFibre preparation Opening, cleaning, blendingCarding

Spinning drawing combing(woolen) roving drawing spinning roving spinning (carded cotton) (combed co & worsted)

Fibre preparation for spinning

Spinning is the actual process where the yarn is formed. But before spinning can commerce, fibres must be prepared so that they satisfy the following key requirements:The fibres are free from impuritiesThe fibres are sufficiently individualised and alignedThe natural properties of fibres are preservedThe fibres are prepared in a form that is suitable for feeding the subsequent spinning process.

Yarn manufacturing process

OBJECTIVES OF THE BLOW-ROOMOpening Cleaning Blending/ Mixing

BLOWROOMBasic operations from bale to sliver: Opening of bales and clumps of fiber and the creation of small tufts of fibers; Cleaning of fibers and removal of dust, dirt & seed; this is done by mechanical means Blending of fibers from different bales (& different parts of bale). These may be nominally the same fiber or different fibers. This is done so as to achieve a homogenous mass of fibres

Blending typeTuft blending - occurs in the stage of opening and cleaning, which blends the fibers within and among bales.Sliver blending - occurs at the draw frame, which usually blends different types of fibers.Blended fibres are then passed through more machines to further open (loosen) the fibre tufts and to clean and remove contaminants which may create serious quality issues if contained within the fibre to the final product

CARDINGBefore the raw stock can be made into yarn, the remaining impurities must be removed, fibers disentangled, and straightenedstraightening process puts the fibers into a somewhat parallel lengthwise alignmentThe initial process of arranging the fibers in parallel fashion is known as cardingThe result from the carding machine is called as card sliver.

The further cleaning and parallelization of fibres in the card is achieved through

Carding process

Carding cotton fibre'sThe lap (1) from the picking operation is unrolled and fed by the feed roll (2), to the licker-in roll (3), which has wire shaped like saw teeth. The licker-in roll moves the lap against cleaner bars (4), that remove trash, and passes it to the large cylinder (5). The surface of the large cylinder holds the cotton with thousands of finewires.Theflats (6), with more fine wires, move in the direction opposite to that of the largecylinder.Thecotton remains on the large cylinder until it reaches the doffer cylinder (7), which removes it from the large cylinder. A doffer comb (8), vibrates against the doffer cylinder and removes the cotton from it. The cotton, in a filmy web, passes through condenser rolls (9),and into a can through a coiler head (10). Objectives of Carding opening the tufts into individual fibres;eliminating all the impurities contained in the fibre that were not eliminated in the previous cleaning operations;selecting the fibres on the basis of length, removing the shortest ones;removal of neps;parallelising and stretching of the fibre;transformation of the lap into a sliver, therefore into a regular mass of untwisted fibreDRAWINGBoth card sliver and combed sliver must go through drawing to receive further blending and alignment. The draw frame corrects for weight variation and fiber misalignment. Drawing is the term applied to the operation involving the doubling and drafting of slivers.

Doubling is the combination of several slivers that are then attenuated by a draft equal in number to the slivers combined, thereby resulting in one sliver of a similar count.Drafting is the process of attenuating the count of a material using a combination of pairs of rollers. A drawing frame uses a series of rollers arranged in pairs and rotating at different speeds, to attenuate, or draft, sliver. At the drawing frame, several card slivers (usually six to eight) are combined to further blend the fibers. The slivers are pulled from the back of the machine through a series of pairs of rollers. Draw frame, drafting arrangement

Objectives of DrawingStraighten the fibers and make them parallel to the central axis of the sliver; Improve short-term, mid-term, and especially long-term evenness in the sliver;Improve consistency of the product delivered to spinning for lower yarn variation; (Blending)Produce the proper weight sliver for the following process. Dust removal

COMBINGCombing is necessary only when combed yarns are being manufactured. It used in producing medium-fine and fine yarns. The following characteristics are improved compared to carded yarns: yarn evenness, yarn strength, yarn cleanness, yarn smoothness and visual appearance.Removal of the short fibers;Removal of non-fibrous impurities which may be called trash, and imperfections such as neps and slubs; Straightening and parallelization of the long fibers which are retained.Objectives of CombingROVINGA roving is a continuous fibrous strand drafted from a sliver and given cohesion by inserting a small amount of twist. It is drafted and twisted to be spun into a yarn.Drawn sliver is presented to the roving frame ( speed frame) in large cans ( normally six cans) . The slivers are drawn from the cans and are forwarded to the drafting arrangement. The drafting arrangement attenuates the slivers with a draft of between 5 and 20. The delivered strand is too thin to hold itself together and a strength-imparting step is necessary immediately at the exit from the drafting arrangement. This is performed by inserting twist.

Tasks of the Roving FrameReduces the weight of the sliver to a suitable size for spinning through drafting Insert small amount of twists to the roving to make it strong enough to sustain the tension in further processing; Winding roving onto the bobbin

Staple spinning processesConventional ring spinningOpen end spinning or rotor spinningAir-jet spinningFriction spinningSelf twist spinningElectrostatic spinningVortex spinningTwist less spinning (Twilo)

Ring spinning The ring spinning frame, commonly called the ring, is the conventional spinning system and it transforms the roving from the roving frame into ring spun yarn using the operations of:Drawing out the roving Inserting twistWinding yarn into bobbinsRing spinning is a comparatively expensive process because of its slower production speeds and the additional processes (roving and winding) required for producing ring spun yarns

Ring spinning produces high quality yarns, mainly produced in the fine (60 Ne, 10 tex) to medium count (30 Ne, 20 tex) range, with a small amount produced in the coarse count (10 Ne, 60 tex) rangeThe drafting system reduces the roving count to an appropriate value so that, on twisting, the required yarn count is obtained.As the front rollers push the drafted material forward, twists are inserted to the fibers as the traveler circulates around the ring. At the same time, the formed yarn is wound onto the bobbin. The amount of twist is proportional to the strength of the yarn

Rotor spinning (open end spinning):The production rates of rotor spinning is 6-8 times higher than that of ring spinning and as the machines are fed directly by sliver and yarn is wound onto packages ready for use in fabric formation the yarn is a lot cheaper to produce. Rotor spun yarns are more even, somewhat weaker and have a harsher feel than ring spun yarns.Rotor spun yarns are mainly produced in the medium count (30 Ne, 20 tex) to coarse count (10 Ne, 60 tex) range. End uses include denim, towels, blankets socks, t-shirts, shirts and pants.

O.E Spinning Sliver is fed into the machine and combed and individualized by the opening roller. The fibres are then deposited into the rotor where air current and centrifugal force deposits them along the groove of the rotor where they are evenly distributed. The fibres are twisted together by the spinning action of the rotor, and the yarn is continuously drawn from the centre of the rotor. The resultant yarn is cleared of any defects and wound onto packages.

Yarn formation in rotor spinning

RING SPINNINGOPEN END SPINNING

Bobbin rotates constantly for Spool does not need to beinsertion of twistrotated to insert twist

Cannot handle spools of Much larger spools bigger size can be wound

Can spin finer yarns Can spin coarser/ carded yarnsFaster production3-5 times faster than ring spinning

Uniform and strong yarnUniform but flexible yarn with better dye abilityRING SPINNINGOPEN END SPINNING

Combed yarns (finer)Carded yarns (coarser)

Yarns for varied Yarns for heavier fabrics applicationssuch as denims, towels andpoplins

Stronger 20% more twisted but 15-20% weaker as the yarn is coarser

Suitable for all stapleNot suitable for MMFibres staple fibre spinning except rayon as the fibre finish clogs the rotor