Yarn manufacturing processes
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Yarn manufacturing processes






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Yarn manufacturing processes Document Transcript

  • 1. Yarn Manufacturing ProcessesOpening, blending, mixing and cleaningStep 1:Typically, mills select bale mixes with the properties needed to produce yarn for a specific end-use. Processing begins when the bales to be mixed are brought to the opening room, wherebagging and ties are removed. Layers of cotton are removed from the bales by hand and placedin feeders. The aim is to begin the sequential production process by converting the compactedlayers of baled cotton into small, light, fluffy tufts that will facilitate the removal of foreign matter.This initial process is referred to as “opening”. The cleaning machines in mills perform thefunctions of opening and first-level cleaning. Dust and impurities are removed and blendingtakes place.Step 2:CardingThe card is the most important machine in the yarn manufacturing process. It performs second-and final-level cleaning. The card successively work small clumps and tufts of fibres into a highdegree of separation or openness, remove a very high percentage of trash and other foreignmatter, collect the fibres into a rope-like form called a “sliver” and deliver this sliver in acontainer for use in the subsequent process.
  • 2. Step 3:Drawing & CombingDrawing is the first process in yarn manufacturing that employs roller drafting. Drafting occurswhen a sliver is fed into a system of paired rollers moving at different speeds. Drawingstraightens the fibres in the sliver by drafting to make more of the fibres parallel to the axis ofthe sliver. Drawing also produces a sliver that is more uniform in weight per unit of length andhelps to achieve greater blending capabilities. Weight per unit length of a finisher-drawing sliveris too high to permit drafting into yarn on conventional ring-spinning systems. Combingupgrades the raw material by removing the short fibers. Combed yarn is more uniform hasgreater shine smoother and pure.Step 4:RovingThe roving process reduces the weight of the sliver to a suitable size for spinning into yarn andinserting twist, which maintains the integrity of the draft strands. The product is now called“roving”, which is packaged on a bobbin.Step 5:Spinning/Ring FrameSpinning is the single most costly step in converting cotton fibres to yarn. Bobbins of roving areplaced onto holders that allow the roving to feed freely into the drafting roller of the ring-spinningframe. Following the drafting zone, the yarn passes through a “traveller” onto a spinning bobbin.The spindle holding this bobbin rotates at high speed, causing the yarn to balloon as twist isimparted. The lengths of yarn on the bobbins are too short for use in subsequent processes andare doffed into “spinning boxes” and delivered to the next process, which may be spooling orwinding. Once the yarn is spun, the manufacturer prepares a correct package. The type ofpackage depends on whether the yarn will be used for weaving or knitting. Winding, spooling,twisting and quilling are considered preparatory steps for weaving and knitting yarn. In general,the product of spooling will be used as warp yarns (the yarns that run lengthwise in wovenfabric) and the product of winding will be used as filling yarns, or weft yarns (the yarns that runacross the fabric).