Friday, July 31, 2009



Yarn is a long continuous length of interlocked fibers, suitable for use in the production of textiles, sewing, crocheting, knitting, weaving, embroidery andropemaking. Thread is a type of yarn intended for sewing by hand or machine. Modern manufactured sewing threads may be finished with wax or other lubricants to withstand the stresses involved in sewing. Embroidery threads are yarns specifically designed for hand or machine embroidery.Yarn is very broad term. Like most things, yarns can have many different characteristics. This is an overview of the different types of yarns used to make sweaters, knit fabrics and woven fabrics. There are different types of yarns which include Partially Oriented Yarns ,Drawn Textured Yarns, Fully Drawn Yarns, High Tenacity Yarns, Polyester Mono Yarns, Polyester Spun Yarns, Embroidery Thread.


There are three major spinning processes: cotton, worsted or long-staple, or wool. Synthetic staple fibers can be made with any of these processes. Since more yarn is produced with the cotton process than the other two, its manufacture is described below.
Preparing the fibers
· 1 Fibers are shipped in bales, which are opened by hand or machine. Natural fibers may require cleaning, whereas synthetic fibers only require separating. The picker loosens and separates the lumps of fiber and also cleans the fiber if necessary. Blending of different staple fibers may be required for certain applications. Blending may be done during formation of the lap, during carding, or during drawing out. Quantities of each fiber are measured carefully and their proportions are consistently maintained.
· 2 The carding machine is set with hundreds of fine wires that separate the fibers and pull them into somewhat parallel form. A thin web of fiber is formed, and as it moves along, it passes through a funnel-shaped device that produces a ropelike strand of parallel fibers. Blending can take place by joining laps of different fibers.
· 3 When a smoother, finer yarn is required, fibers are subjected to a further paralleling method. A comblike device arranges fibers into parallel form, with short fibers falling out of the strand.
Drawing out
· 4 After carding or combing, the fiber mass is referred to as the sliver. Several slivers are combined before this process. A series of rollers rotating at different rates of speed elongate the sliver into a single more uniform strand that is given a small amount of twist and fed into large cans. Carded slivers are drawn twice after carding. Combed slivers are drawn once before combing and twice more after combing.
· 5 The sliver is fed through a machine called the roving frame, where the strands of fiber are further elongated and given additional twist. These strands are called the roving.
· 6 The predominant commercial systems of yarn formation are ring spinning and open-end spinning. In ring spinning, the roving is fed from the spool through rollers. These rollers elongate the roving, which passes through the eyelet, moving down and through the traveler. The traveler moves freely around the stationary ring at 4,000 to 12,000 revolutions per minute. The spindle turns the bobbin at a constant speed. This turning of the bobbin and the movement of the traveler twists and winds the yarn in one operation.
· 7 Open-end spinning omits the roving step. Instead, a sliver of fibers is fed into the spinner by a stream of air. The sliver is delivered to a rotary beater that separates the fibers into a thin stream that is carried into the rotor by a current of air through a tube or duct and is deposited in a V-shaped groove along the sides of the rotor. As the rotor turns, twist is produced. A constant stream of new fibers enters the rotor, is distributed in the groove, and is removed at the end of the formed yarn.


Spinning systems and yarn manufacturing machinery will continue to become more automated and will be integrated as part of a manufacturing unit rather than as a separate process. Spinning machines have already been developed that combine carding and drawing functions. Production rates will increase by orders of magnitude as machines become available with even more spindles. Robot-controlled equipment will become standard.
Domestic yarn producers will continue to be threatened by competition from Asian countries, as these countries continue to buy the latest textile machinery technology. Higher domestic material prices will not help, since the cost of the raw material can represent up to 73% of the total cost of producing the yarn. U.S. yarn producers will continue to form alliances with their customers and customers' customers to remain competitive. The textile industry is also forming unique partnerships. The American Textile Partnership is a collaborative research and development program among industry, government, and academia aimed at strengthening the competitiveness of the U.S. industry.
Another continuing challenge for the industry will be compliance with stricter environmental regulations. Recycling is already an issue and processes are under development to manufacture yarn from scrap material, including denim. Yarn producers will have to incorporate pollution prevention measures to meet the air and water quality restrictions. Equipment manufactures will continue to play an important role in this endeavor.
Genetic engineering will become more widely used for developing fibers with unique properties. Researchers have developed genetically-altered cotton plants, whose fibers are especially good at retaining warmth. Each fiber is a blend of normal cotton and small amounts of a natural plastic called polyhydroxybutyrate. It is predicted that dye-binding properties and greater stability will be possible with new fibers in the next generation.
New synthetic fibers will also be developed that combine the best qualities of two different polymers. Some of these fibers will be produced through a chemical process, whereas others will be generated biologically by using yeast, bacteria, or fungi.

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