Friday, January 11, 2013

Weft Knitting, Produce weft knitted fabric

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Weft Knitting 
There are three fundamental stitches in weft knitting: (1) plain knit stitch, (2) purl stitch, (3) rib stitch. Novelty stitches are variations of these three stitches. The hand method of knitting is weft knitting. On a knitting machine, the individual yarn is fed to one or more needles at a time 

1. Plain-knit Stitch: The plain knit is the basic form of knitting. It can be produced in flat-knit or in tubular (or circular) form. The flat knit is also called jersey stitch because the construction is like that of the turtleneck sweaters originally worn by English sailors from the Isle of Jersey; it is sometimes called balbriggan stitch after the hosiery and underwear fabrics made in Balbriggan, Ireland. Plain flat knits may be shaped or full-fashioned. The knitting is done with a row of latch or beard needles arranged in a linear position on a needle plate or in a circular position on a cylinder. All the needles are evenly spaced side by side and are moved by cams, which act on the needle butts. The spacing of the needles is referred to as the gauge, gage, or cut. As applied to many flat knits and some circular ones, gauge refers to the number of needles in 11/2 inches; for example, a 60-gauge machine would have 40 needles per inch. 

2. Purl Stitch: This construction is also referred to as the link-sand links stitch after the German word “links,” or on the left). It is made on flat-bed and circular machines by needles using hooks on both ends to alternately draw loops to the front of the fabric in one course and to the back in the next course. It is a slower and more costly technique. The fabric looks the same on both sides and resembles the back of the plain knit. Like the plain knit, the purl knit will run up and down if a loop is broken. But a purl knit fabric will not curl at the edges. 

3. Rib Stitch: Rib-knit fabrics have alternating lengthwise rows of plain and purl stitches constructed so that the face and back of the fabric appear alike. This may be produced either on a flat rib machine or a circular rib machine. In the flat rib machine, one set of needles is placed opposite the other set of needles is placed opposite the other set of needles in an inverted V position of 45 degrees to the horizontal; in the circular rib machine, one set of needles is placed vertically in a cylinder and the other set of needles is placed horizontally on a dial. In both machines, one set of needles pulls the loops to the front and the other set pulls the loops to the back of the fabric. Each set of needles alternately draws loops in its own direction, depending upon the width of the rib desired. 

For example, rib stitches can be 1 x 1, 2 x 2, 2 x 1, 3 x 1, and so on. A combination of 1 x 1 and 2 x 2 is called an accordion rib. Rib construction is costlier because of the greater amount of yarn needed and the slower rate of production Rib knits are made on a two-bed machine with one set of needles forming the loops for one wale and the other set of needles forming the alternating wale.Rib knits have greater elasticity in the width than in the length. They are stable and do not curl or stretch out of shape as do the jersey knits. For this reason, they are often used to make cuffs and necklines on weft knitted garments. Rib knits are reversible unless the number of stitches in the alternating wales is uneven, as in a 2 X 3 rib.
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Thursday, January 10, 2013

Knit Fabric; Different types and classification of knitted fabric

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Single Jersey Knits Fabric  
Knitting Machines with one needle bed and one set of needles are called jersey machines or single-knit machines. With one set of needles used for knitting and one needle bed, all needles face the same direction; all stitches are pulled to the same side of the knitted fabric. As a result, single jersey fabrics have a smooth face with a vertical grain on the right side of the fabric and a width wise grain on the back side. The knittig loops formed by the jersey machine are formed in one direction only, which gives a different appearance to each side of the fabric. The basic knit fabric produced by this knitting machine is known alternately as a plain, single knit, or jersey. The terms are interchangeable.Jersey stretches slightly more in the crosswise than the lengthwise direction. If one stitch breaks, the fabric may ladder, or run. Jersey fabrics tend to curl at the edges and are less stable than are some other types of knits. This is the result of the pressures exerted during knitting. In addition jersey knits may twist or skew after laundering, as the twisting tensions imposed during the knitting process are relaxed. 

Special finishing techniques are used to overcome these tendencies and maintain fabric stability; the principal ones use starches, gum mixtures, polyvinyl acetate emulsions, and resins. 

A great many items of hosiery, sweaters, and other wearing apparel are made from plain jersey knits. Consumer Brief 16.1 highlights one of the common uses of jersey knit fabrics: Tshirts. Plain knit fabrics can also be made into designs of two or more colors by use of a patterning mechanism that controls the selection and feeding of yarns and types of stitches to create jacquard knits. 


Double Jersey Knit Fabrics 

The term double knit is generally applied by consumers to fabrics that are, technically, double jersey fabrics. Double jersey fabrics are also made on two-bed knitting machines, but the arrangement of the needles is different from that for knitting rib fabrics. The layers of loops alternate from one side to the other, locking the two layers together. Double knit fabrics have the same appearance on both sides of the fabric, that is, exhibiting the appearance of the face or outer side of a single knit on both sides. Twice as much yarn is incorporated into double knit fabrics as into comparable single knits 


Interlock Knit fabric

Interlock knits are produced on a special machine that has alternating long and short needles on both beds. Long and short needles are placed opposite each other. Long needles knit the first feeder yarn; short needles knit the second feeder yarn. The fabric created is an interlocking of two 1 X 1 rib structures. The resulting fabric, like double knit fabrics, is thicker than single knit fabric, and more stable in the width wise direction. Interlock fabrics have been traditionally used for underwear. They are produced more slowly than are other rib knits and are generally made in plain colors or simple patterns because the addition of pattern slows down the manufacture even further 


High Pile Fabrics 

High-pile fabrics, such as imitation furs and plushes, are usually knitted by a jersey machine. While the knitting is taking place, a sliver of staple fiber is fed into the machine. These fibers are caught in the tight knit and are held firmly in place. Although any staple fiber can be used for the pile, the greatest quantity of these fabrics are made with acrylic and modacrylic fibers in the pile. By using staple fibers of varying lengths, adding color through fiber dyeing or printing on the surface of the pile, and by shearing or brushing the pile, an enormous variety of effects can be achieved. The use of knitted pile fabric ranges from excellent imitations of furs, such as leopard, tiger, mink, or mouton, to colorful pile outerwear, coat linings, or pile carpet fabrics.
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Gauge and Quality; Knitting machine element to produce knit fabric

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Gauge and Quality 
The size of the needle and the spacing of the needles on knitting machines determine the number and size of the knit stitches and their closeness those are known as knitting element. Each wale is formed on one needle. The number of needles is equal to the number of Wales. The closeness of the stitches determines whether a knit fabric will be lightweight and open or heavier and more dense. The term gauge is used to describe the closeness of knit stitches. Gauge is the number of needles in a measured space on the knitting machine. Higher-gauge fabrics (those with more stitches) are made with finer needles; lower gauge fabrics are made with coarser or larger needles. 

The term cut is also used to designate the number of needles per inch in the needle bed of a circular weft knitting machine. To describe the stitch density of a single or double knit fabric, the fabric may be designated as an 18-, 20-, 22-, or 24cut fabric. The higher the cut, the closer the stitches; the lower the cut, the coarser the fabric. 

Varying types of knitting machines measure gauge over different distances on the machine. For example, circular knit hosiery measures the number of needles in 1.0 inch, fullfashioned knitting in 1.5 inches, and Raschel knits in 2.0 inches. 

Because of these differences, it is best to keep in mind the generalized principle that the higher the gauge, the closer the stitches. 

The quality of needles used in manufacturing knit goods is related directly to the quality of the fabric produced. Needles of uneven size and quality will produce knit fabrics with unevensized stitches and imperfect surface appearance. 

In warp knits, those knits in which the yarns interlace in the long direction, one or more yarns are allotted to each needle on the machine, and those yarns follow the long direction of the fabric. For weft knits, those in which the yarns interlace crosswise or horizontally, one or more yarns are used for each course, and these yarns move across the fabric. In weft knits, one yarn may have from twenty to several hundred needles associated with it. To summarize, weft knits can be made with one yarn, but warp knits must have a whole set of warp yarns, that is, one or more for each needle. 

Once the basic distinction between warp and weft knits has been made, further subdivisions of knit classifications are usually based on the types of machines used in their production. The majority of knit fabrics are named after the machines on which they are constructed. For this reason, the discussion of knitted fabrics that follows is organized around the types of machines used in manufacturing knit fabrics and the types of knit fabrics made on these machines. 

1. Flat or circular jersey, or single knit, machine: one needle bed and one set of needles. 
2. Flat or circular rib machine: two needle beds and two sets of needles. 
3. Flat or circular purl, or links-links, machine: two needle beds and one set of needles.
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Loop Formation in knit fabric structure

Loop Formation 
The spring beard needle is formed from one piece of thin wire. One end of the needle is drawn into thinner dimensions and is curved to form a hook. The flexible outer side of the hook can be pressed against the stem of the needle to close the hook for sliding a formed loop off and beginning a new loop. In 1847 Matthew Townshend invented a different type of hook known as the latch needle, which has come to be the most widely used type of needle. Its operation s similar to that of the spring beard needle, except that instead of having to mechanically press the flexible wire of the needle closed so that the forming yarn loop will not slide off, a latch closes to hold the yarn in place. 

1. The old loop is held on the stem of the needle. The latch is open (a). 
2. The hook grasps the yarn to begin forming a new loop (b). 
3. The needle falls, the old loop rises, closing the latch of the needle (c). 
4. The old loop is cast off (d and e). 
5. The needle tises, and the new loop slides down to the stem of the needle, pushing the latch open again, and the needle is ready to repeat the cycle (f).

Loop formation in knit fabric

Yet a third type of needle, the compound needle, is used almost exclusively for warp knitting. The compound needle has two components, a tongue and a hook Its motion is as follows: 

1. The old loop encircles the hook; the tongue is in such a position as to leave the hook open. 
2. Both tongue and hook rise; a new yarn is fed to the hook. 
3. Both tongue and hook descend, but the tongue descends more slowly, thereby closing the hook. 
4. As the needle descends, the held loop slides off, forming a new loop. 
5. The needle returns to its initial position, the hook ascending more rapidly, thereby opening the hook again. 

For weft knitting with either needle type, a cam system provides the action for lifting the needles as the yarn is fed in. A small projection called a butt is located at the bottom of the needle. The butt is held in a groove formed by a system of cams or shaped pieces. The movement of the butt in the grooves between the cams causes the needle to rise and fall. 

The engaging by the needle of a new piece of yarn is called feeding. Devices called feeders are located to introduce the yarn to the needles. The number of feeders can vary, but obviously the more feeders a machine has, the higher will be the speed of fabric forming on the machine, since each needle produces a loop each time it is activated and if many needles are activated more frequently, many courses can be formed at the same time. 

Another important element of some knitting machines is the sinker. The already formed fabric may need to be controlled as the subsequent knitting action takes place. A thin steel device called the sinker may be used to hold the fabric as the needle rises, support the fabric as the needle descends, and push the fabric away from the needle after the new loop has been formed. Sinkers are generally mounted between the needles. Some machines, however, do not use sinkers but instead use the tensions placed on the completed fabrics for control.

Construction of Knit Fabric

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The construction of knitted fabrics is evaluated by the number of stitches or loops. When the interlocking loops run lengthwise, each row is called a wale. A wale corresponds to the direction of the warp in woven fabrics. When the loops run across the fabric, each row is called a course. A course corresponds to the filling, or weft. Thus, a knitted fabric having 40 loops or stitches in 1 inch of width, and 50 loops in 1 inch of length, is said to have 40 Wales and 50 courses.
Construction of Knit Fabric

The major difference between knitted and woven structures lies in the way the yarns are interconnected geometrically. In weaving, two sets of parallel yarns are interconnected by interlacing them at right angles. Different woven structures are produced by varying this basic principle In knitting, the yarns are initially formed into loops, and then these loops are interconnected in order to produce a textile structure. The term interlooping is used to describe this technique of forming fabrics. Based on this principle, a textile fabric is produced by using only one set of yarns. Thereby, a horizontal set of yarns (weft) could be interlooped to produce a weft knitted fabric, and a vertical set of yarns (warp) could be used to produce a warp knitted fabric. As a result of this interlooping of yarns, the surface of a weft or a warp knitted fabric is more open when compared to the surface of a woven fabric. Due to this interlooping of yarns a knitted fabric could be stretched more than a woven fabric, even when a small force alone is applied. 

Once this force is eased the fabric slowly returns to its original dimensions. In fact, weft and warp knitted fabrics have higher elongation values than woven fabrics due to their structure, and their elastic behaviour generally exceed the elastic properties of the yarns used to knit the fabric. 

Yarns have poor bending and tensional properties compared to their longitudinal elastic properties, and so once a knitted fabric is stretched and then released, it would slowly go back to its original state. The absolute elongation and the elastic behavior of the fabric are both determined by the knitted structure and the mechanical properties of the yarns used to knit the fabric. Due to the structure and good elastic behaviour of knitted fabrics, garments made of knitted fabrics (knitted garments) are comfortable to wear. The air trapped in the loops of a knitted garment insulates the human body against cold. At the same time the relatively loose and open structure helps the perspiration process of the human body, especially when the knitted fabric is made of yarns spun from natural fibers. Due to the interlooping of yarns, the knitted fabrics also have better crease recovering properties compared to fabrics woven from similar yarns. 

The term binding can be used to describe the connection of one or more yarns in a textile fabric. The structure of a knitted fabric can be evaluated by studying how the yarns in weft and warp knitted fabrics are bound or interconnected, and this can be illustrated using stitch (loop) diagrams (charts). The actual interlooping of yarns in order to produce knitted structures depends on the knitting principle that was adopted to produce the structure, i.e. weft or warp knitting, and on the patterning elements. Knitting is the process of making cloth with a single yarn or set of yarns moving in only one direction. Instead of two sets of yarns crossing each other as in weaving, the I single knitting yarn is looped through itself to make a chain of stitches. These chains or rows are connected side by side to produce the knit cloth” (American Fabrics and Fashions Magazine 1980, 370). The interlocking of these loops in knitting can be done by either vertical or horizontal movement. When the yarns are introduced in a crosswise direction, at right angles to the direction of growth of the fabric, and run or interlock across the fabric, the knit is known as a weft knit. (Some sources may refer to these knits as filling knits, but the term weft knit is used in the knitting industry.) 

When the yarns run lengthwise or up and down, the knit is known as a warp knit. In knitting terminology, the rows of stitches that run in columns along the lengthwise direction of the fabric are known as wales. This corresponds to the warp direction of woven fabrics. Crosswise rows of stitches or loops are called courses. The direction of the courses corresponds to the filling of woven goods. 

Both warp and weft knits are made by machine. Knitting machines may be either flat or circular. The flat-type knitting machine has needles arranged in one or two straight lines and held on a flat needle-bed. The cloth is made by forming stitches on these needles. The resulting fabric is flat. Machines with flatbeds are used to make both warp and weft knits. 

The circular knitting machine has needles arranged in a circle on a rotating cylinder. The resulting fabric is formed into a tube. Circular knitting machines produce weft knits almost exclusively. For nearly two hundred years after its invention in 1589, Lee’s machine was used without further improvement. Using a spring beard needle, Lee’s machine produced flat knitted fabrics by mechanically passing one loop of yarn through another.

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Care of Knit Fabric

Care must be taken for Knit Fabrics 
Although there is a great variety in the quality of knitted goods sold, and the performance of any individual knit may differ markedly from that of other knits, some general guidelines for the care of knitted goods can be observed. The problems that consumers seem to encounter most often in the performance of knitted fabrics are in the areas of dimensional stability, snagging, and pilling.

Dimensional Stability

One reason for the popularity of knits for wearing apparel is their comfort. The looped construction of knit fabrics permits the fabric to give with the body as it moves. But the stretchiness of knits also results in lessened dimensional stability. Consumers have complained about shrinkage, stretching, and distortion of knits, although interlock and double knit fabrics are usually more stable and display little or no shrinkage. Similarly, fabrics with weft or warp inserted yarns are more stable. Shrinkage control treatments, heat setting of synthetics, and special resin finishes can provide good dimensional stability for knits. Unfortunately, not all manufacturers provide such treatment for their products. Consumers should check labels for percentage of shrinkage or for other special treatments to judge potential dimensional stability. (About 3 percent shrinkage is one garment size.) If products fail to live up to specified performance standards, items should be returned to the retailer or the manufacturer.

Knits are considered to be easy-care fabrics, and many care labels recommend machine washing. Some labels will also specify that the fabric can be dried in an automatic dryer. In general, however, knits will shrink more in the dryer than if air dried. Knits maintain their shape best if they are dried flat. The weight of a wet knit, hung on a line, may cause the fabric to stretch out of shape. The dimensions of knits usually will be retained best by professional dry cleaning. Hand knits, sweaters of wool or animal hair fiber, and other knits with an open construction may require special hand laundering and blocking (stretching back into shape). Such items should be laid on a sheet of wrapping paper before washing, and the outlines traced. After washing, the garment should be stretched out on the paper to dry. While still damp, the garment should be gently stretched to fit the outline of the original dimensions.

Aside from stretching or shrinking, an additional problem with knitted items is skewing or twisting as the fabric is relaxed during laundering. Side seams of garments may pull to the front or back and hems may hang unevenly. In general, knits made of synthetics will have better resistance to stretching out of shape than will cotton, acetates, and rayons. Blending of synthetics with cottons, acetates, and rayons will improve the resiliency and dimensional stability of knitted fabrics made from these fibers. Price is a good guide-especially for children’s knits.

Mechanical Damage
The loop structure of knitted fabrics makes them especially susceptible to snagging. If a loop catches on another object, it may be pulled up from the fabric surface and a long snag, or pull, of yarn may be formed. If the yarn that has been snagged is not broken, it can be pulled to the back of the fabric. It may be possible to gently stretch the fabric and work the pulled yarn back into place. This is difficult to do with tightly knitted fabric structures. If the yarn has been broken, the snag may produce a hole in the fabric. A few hand stitches with needle and matching thread should be made to secure the yarns so that the hole does not become enlarged during wearing or laundering. Synthetic double knits or knits made from loosely twisted yarns may be subject to pilling. Weaker fibers, such as cotton, rayon, acetate, and wool, generally break off the fabric, but the stronger synthetic fibers cling to the fabric, making an unsightly area on the fabric surface. The use of textured yarns for knitting synthetics decreases the likelihood of pilling. Knits may be damaged by sharp objects puncturing the fabric. If yarns are cut, a hole will result, and further pressure and strain on the fabric may enlarge the open area, as loops are dropped in the interlocking structure.

Effects of Knit Structure on Knitted Fabric Performance

Knit fabrics are most comfortable, durable and make most flexible effect on human body. I am going to describe the effect of knitted structure on knit fabric performance in details. 


Durability Factors 

Strength of knitted fabrics is considered to be less important for durability than it is in woven goods. Knitted fabrics are easily stretched to accommodate changes of shape as a result of stresses imposed in wear and care. When knits are made from resilient fibers and yarns, the ability to stretch and recover from stretching will be enhanced. In comparison to knitted fabrics, woven fabrics are generally firmer and have less elongation. In knits the loops in the structure can be deformed horizontally or vertically, increasing the stretch in both directions. But, as noted earlier, variations in knitting techniques can increase or decrease extensibility of knitted fabrics. Double knit fabrics and warp knit fabrics are usually less extensible than single knit fabrics.A major problem in the durability of knits is the runs that can develop in weft knits when one of the loops is broken. If stronger fibers and yarns are used in these knits, they will be less likely to run. 


Appearance 
Shear ability, discussed in chapter 15, is an important factor in the appearance of textiles. In general, because of the ways in which yarns are combined, woven fabrics have higher shearability than do knitted fabrics. Knitted fabrics have good flexibility and are easily extended. Warp knits do not shear as easily as weft knits. 

These qualities must be taken into account by designers, although they may not be aware of the technical terminology used to describe the fabric properties. For example, a warp knit tricot fabric with low shearability would not be used to make a bias-cut garment in which the intention is to take advantage of high shearability. Instead, the designer would be likely to use a soft, gathered construction where the high flexibility of the fabric would work to good advantage, but where most of the draping would fall in the vertical direction of the fabric. In general, knits wrinkle less than do other fabrics. This is because loosely constructed fabrics generally allow more fiber redistribution and motion. However, knitted fabrics, because of their greater extensibility, are more likely to lose their shape in laundering. The stresses applied in knitting distort the shapes of the loops rather than just stretching the yarns as in weaving. On relaxation, the loops broaden, shrinking the fabric length and increasing the width. As with woven fabrics, the tighter the structure, the higher the shrinkage until the structure becomes so tight that further shrinkage is not possible. Such fabrics may, however, buckle. 

Knitted fabrics tend to have lower cover than do woven fabrics, with weft knits having substantially more porous structures than warp knits, unless the fabric is deliberately made to have an open, lacy construction as in some Raschel knits. Use of thinner or thicker yarns can increase the cover of knitted fabrics. 


Comfort Factors
Knits usually entrap more air than woven fabrics, although the tightness of the knit is a factor as well. Pile or napped knit constructions are especially good for cold weather because the yarns or fibers perpendicular to the surface provide numerous spaces for dead air. This effect is maximized if such fabrics are worn with the napped or pile surface next to the body, or if they are covered with another layer. The flexibility of knits contributes to a feeling of fabric softness. Fibers and yarns used can enhance or detract from the smoothness of knitted fabrics. 


Elongation and Recovery 
The majority of bathing suits for women, and many for men, are tight fitting, with stretch required for getting the garments on and off. Since knits have much higher elongation than woven or nonwoven fabrics, they are the preferred fabric construction for bathing suits that fit tightly to the body. Fibers too play an important role in achieving tightness of fit. Those with lower modulus and high resilience will enhance the stretch and recovery properties of knits. Not only elastomeric fibers but also nylon have low modulus and good recovery. Nylon and spandex are often chosen for swimwear because of these properties. Polyester is not usually used because it has a higher modulus and therefore does not stretch as easily. Knitted fabrics of nylon blended with elastomeric fibers, such as spandex or rubber, will provide the highest amount of stretch. The elastic fibers also have high recovery from stretch. 


Colorfastness 
Bathing suits are exposed to sunshine, chlorine and other chemicals in swimming pools, and salt water in oceans. Fibers and yarns are both important in maintaining the colorfastness of swimming suits that are often made of bright-colored fabrics. Light-fastness of dyed spandex is fair to good, while that of nylon dyed with acid dyes is good. Spandex normally makes up only a small percentage of the fiber content of swimwear fabrics and is often used in core-spun yarns wrapped with nylon. This helps to protect ir from sunlight. Colorfastness of nylon and spandex exposed to pool and salt water is fairly good but these fabrics will show some loss over time. 


Absorbency 
Since bathing suits are worn while swimming in water, the absorbency of the fabric is a consideration. If a material absorbs and retains a significant amount of water, the weight of the suit will increase, affecting its comfort and function. Synthetic fibers have low water regain and are more appropriate for bathing units than the natural fibers that were used many years ago. 


Environmental Resistance 
Light, chlorine, and salt water can also degrade textile fibers. When this occurs, bathing suit fabrics may lose some of their recovery from stretch. Nylon and polyester are more resistant to ultraviolet light and chlorine than spandex. That is another reason why spandex is usually used in small percentages blended with nylon. The use of rubber as an elastomeric fiber in swimwear has decreased because of its susceptibility to degradation by light and other environmental conditions. Because resistance of nylon to degradation by light is higher for fibers that have not been delustered, brighter nylons are usually used in swimwear.
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Wednesday, January 9, 2013

Pile Weave; Produce woven fabric with Warp Pile and Filling Pile

Pile Weave
Extra sets of warps or fillings are woven over ground yarns of plain or twill weave to form loops. Pile fabrics have been defined as “fabrics(s) with cut or uncut loops which stand up densely on the surface” (Klapper 1967,64). Pile fabrics may be created by weaving or through other construction techniques, such as tufting, knitting, or stitch through. To create the loops that appear on the surface of woven pile fabrics, the weaving process incorporates an extra set of yarns that form the pile. Construction of woven pile fabrics, therefore, represents a complex form of weaving in which there are at least three sets of yarns. 

Woven pile fabrics are divided into two categories depending on whether the extra set of yarns is in the warp direction or the filling direction. Warp pile fabrics have two sets of warp yarns and one set of filling yarns. Filling pile fabrics have two sets of filling yarns. Pile fabrics are woven by one of several methods, depending on whether they are warp pile or filling pile fabrics. 

Warp Pile Fabrics 
Warp pile can be made by the wire method, the double-cloth method, or by slack tension weaving.In the wire method one set of warp yarns and the filling yarn interlace in the usual manner and form the “ground” fabric in either a plain or twill weave. The extra set of warp yarns forms the pile. When the pile yarns are raised by the heddles, the machine inserts a wire across the loom in the filling direction. When the warps are lowered, they loop over the wire to make a raised area. The next several filling yarns are inserted in the usual manner. The wire is then withdrawn, leaving the loop, which is held firmly in place by the other yarns. Frieze, a fabric often used for upholstery, is an example of an uncut, looped pile fabric that can be made by the wire method. If the fabric is to have a cut pile, the wire has a knife blade at the end that cuts the yarns as the wire is withdrawn. 

Velvets may be made in this way. If the fabric is to have an uncut pile, the wire has no cutting edge. The double-cloth method is used for cut pile fabrics. Here, two sets of warps and two sets of fillings are woven simultaneously into a layer of fabric. A third set of warp yarns moves back and forth between the two layers of fabric, holding them together and being held by each fabric. The resultant fabric is cUt apart by a sharp knife, thereby creating two lengths of fabric, each with a cut pile. Velvets and flushes can be made with the double-cloth method. Velvets are usually made of filament yarns. Other nonpile fabrics can be made by the double-cloth method, and are discussed later.Terry cloth is made by the slack tension method. Terry cloth is made with uncut loops. Usually, two sets of warps and one set of filling yarns are used; however, more expensive fabrics may use two sets of yarns in each direction. The ground of the fabric is of warp yarns held under tension, the pile of warp yarns that are allowed to relax. 

Periodically (usually after every three picks), tension is released on the warp pile yarns at the same time as the next three filling yarns are pushed firmly into place. The first two of each three picks are only beaten up part way. The loose warp yarns loop up on the surface to form the terry pile. Loops may remain uncut to form the traditional terry cloth with loops on both sides. 

Sometimes one side is sheared to make an attractive velour face. Such fabrics do not wear as well as uncut loop fabrics. Pile yarns in velour toweling tend to become dislodged more easily, thereby shortening the wear life of the material. Terry pile may appear on one or both sides of the fabric. 

Filling Pile Fabrics 
Filling pile fabrics are woven by the filling pile method. In this method there are two sets of filling yarns and one set of warp yarns. The extra set of filling yarns forms floats that are from four to six yarns in length. The floating yarns are cut at the center of the float, and these ends are brushed up on the surface of the fabric. In some filling pile constructions, the filling yarn that makes the pile is interlaced with the ground one time before it is cut;’ in others, the filling pile interlaces twice. Those fabrics in which there are two interlacings are more durable than when only one interlacing has taken place. Floats for corduroy are placed in lengthwise rows, and floats for velveteen are spaced to produce an overall pile effect. Velveteens are characterized by a uniform, overall pile. The even spacing of corduroy floats produces a strip or wale characteristic of this fabric 

Corduroys are given names according to the numbers of wales. Feathercord corduroy has about 20 to 25 lengthwise wales per inch; fine wale or pinwale corduroy, about 16 to 23 wales; mid, medium, or regular wale corduroy, about 14 wales; wide wale corduroy, about 6 to 10 wales; and broad wale corduroy, about 3 to 5 ribs per inch. Novelty wale corduroys are also produced in which thick and thin wales are arranged in varying patterns. Some corduroy fabrics are now made with 100 percent cotton yarns in the pile filling and polyester and cotton blends in the ground yarns. Other decorative effects can be achieved by cutting floats selectively to vary pattern and texture. Most filling pile fabrics are made from spun yarns.

Variations of the Weaves; Different types of special woven fabric

Variations of the Basic Weaves

Dobby Fabrics 
The dobby weave is like a jacquard weave in miniature. The Dobby weaves have small, repeated patterns, that are usually geometric. The following are some of the fabrics made on the dobby loom. 

1. Birds eye, a cloth made with small diamond-shaped figures, has a weave that is said to resemble the eye of a bird. Bird’s eye is also called diaper cloth. 
2. Pique is a medium- to heavyweight fabric, often of cotton, with a pronounced lengthwise cord, often combined with other small figures or patterns such as honeycomb or waffle effects. 
3. White-on-white has a white dobby figure woven on a white background and is often used for men’s shirting. 

Jacquard Fabrics 
Jacquard patterns, when carefully analyzed, may be seen to contain combinations of plain, twill, and satin weaves, even in the same crosswise yarn. Many decorative fabrics are made by the jacquard technique. Jacquard-woven tapestry fabrics should not be confused with true tapestries (see below) even though some fashion promotions may refer to jacquard fabrics as “tapestry fabrics.” 

The following are some of the best-known jacquard patterns. 
1. Brocade features an embossed or embroidered appearance. Elaborate patterns, often of flowers and figures, stand out from the background. Pattern and ground are usually different weaves. Brocades are made from a wide range of fibers and with a wide range of price and quality. Fabrics are used for upholstery, draperies, and evening and formal clothing. 

2. Brocatelle is similar to brocade, but with figures or patterns standing in high relief Brocatelle is used mostly for upholstery fabrics and draperies. 

3. Damask is a flatter fabric than brocade and often has a fine weave. Damask figures often use a satin weave to reflect light from the pattern, whereas the background is made in a plain or twill construction. Linen damasks have long been used for luxurious tablecloths. Damasks are reversible. Cotton and linen damasks are made either with four-yarn float or a seven-yarn float in the satin weave. The longer floats are more lustrous, but the shorter floats are more durable, as they are less likely to snag or be subject to abrasion. 

4. Tapestry-like fabrics have an appearance that simulates handwoven tapestries. Used extensively in fabrics for interiors, these jacquard-woven fabrics have highly patterned designs on the face. Although the back is also figured, the colors within the design differ. For example, a leaf that appears on the face as green will be some other color on the back.






Others Variations of Weaves 

Leno or Gauze Weave: 
In leno or gauze weave pairs of warps are twisted over each other with each passing of filling yarn. The leno weave is the modern descendant of a technique called twining that was used thousands of years ago for making fabrics. In leno-weave fabrics, the warp yarns are paired. A special attachment, the doup or leno attachment, crosses or laps the paired warp yarns over each other, while the filling passes through the opening between the two warp yarns. Leno-weave fabrics are made in open, gauzelike constructions. The twined (not twisted) warp yarns prevent the filling yarns of these open fabrics from slipping. Curtain fabrics are often made with leno weave. Two of the more popular leno-weave fabrics are marquisette and grenadine. Many fruit sacks are leno-woven of slit films 

Characteristics: 
• Open-mesh appearance with yarns securely held 
• Sheer but durable for its weight 
• Ex: Grenadine, Marquisette 

5. Pile Weave: 
Extra sets of warps or fillings are woven over ground yarns of plain or twill weave to form loops. Pile fabrics have been defined as “fabrics(s) with cut or uncut loops which stand up densely on the surface” (Klapper 1967,64). Pile fabrics may be created by weaving or through other construction techniques, such as tufting, knitting, or stitch through. 
There are two types of pile fabric
1. Filling Pile Fabrics
2. Warp Pile Fabrics

6. Swivel Weave: 
The swivel weave is the method by which decorative effects, such as dots, circles, or other figures, are interwoven on the surface of a fabric while it is being constructed on the loom. The weaving of the design requires an extra filling yarn and additional small shuttles or insertion devices. Similar fabrics can be made in the swivel weave, which is sometimes used in decorative fabrics for interiors. The design is made by supplying an extra filling yarn on a small shuttle or swivel. The filling design yarns are carried several times around a group of warps by the motion of the swivel to prevent the yarn from pulling out ofthe background fabric. The long floats between designs are knotted and clipped off. Occasionally, imported dotted Swiss fabrics may use a swivel weave rather than a clipped spot weave. The swivel weave is more durable than the clipped spot weave because the design yarns are woven in and cannot pull out of the fabric as easily as in the latter method. When the floats at the back have been cut away they are called clipped swivel patterns 

6. Lappet Weave: 
Lappet weave is also used to superimpose a small design on the surface of a fabric while it is begin woven. In the lappet weave, the design is stitched into the fabric by needles that operate at right angles to the construction. Thus the lappet weave is very similar to embroidery. Lappet weaves have an extra warp yarn that may interlace in both the warp and filling direction with the ground fabric. The extra set of warps is threaded through needles set in front of the reed. The yarns are carried in a zigzag direction, back and forth to form an embroidery like design. 

The design is created on the right side of the fabric, the excess yarn being carried along on the wrong side. Extra yarn is not clipped away from the back of the fabric but can be seen as it is carried from one design area to another. 

7. Dobby Weave: 
The dobby weave is a patterned weave used to construct small. Geometric designs composed of short floats created on a loom by a special attachment called a dobby, which raise or lowers as many as twenty-four to forty harnesses. The design is usually small and does not make use of long floats. 

8. Jacquared Weave: 
A jacquard pattern is a design, which contains very detailed, unlimited range of intricate designs. Any combination of weaves and patterns is possible.Since these designs exceed the capacity of the harness looms, a special loom called a Jacquard looms, a special loom called a Jacquard loom is used. Here, each warp is individually controlled. Almost any design desired can be made. Durability depends upon weave and yarn. E.g.: Brocade, tapestry, damask



Novelty Fabrics from Basic Weaves

Novelty effects in fabrics are in large part a result of selection of novelty yarns for incorporation into fabrics made in one of the basic weaves. 

Crepe Fabrics 
Crepe weave fabrics is special novelty fabrics from basic weaves may be defined as fabrics characterized by a crinkled, pebbly surface. Originally, crepe fabrics were made from crepe yarns, that is, yarns with an exceptionally high degree of twist, up to sixty-five turns per inch. Most standard crepe fabrics were made in the plain weave, some with rib effects, and some in satin weave, as in crepe-backed satin. With the advent of synthetic fibers, however, many crepe effects are achieved through the use of textured yarns, bicomponent yarns in which uneven shrinkage creates a crepe like surface, or embossing or stamping a crepe like texture on the surface of the fabric. Most fabrics made from these more recent processes will be durable only if they are made from heat-treated thermoplastic fibers. Another method uses a special crepe weave that breaks up the surface of the cloth into a random sequence of interlacings. Careful examination of fabrics having a crepe like appearance will reveal that relatively few of them are actually woven with crepe yarns. 

Seersucker 
Seersucker, another plain-weave fabric, is created by holding some warp yarns at tight tension, some at slack tension. Those at slack tension puff up to form a sort of “blister effect.” Seersucker surface effects are permanent. Often the slack and tight yarns are each made from a different colored yarn, to provide a decorative striped effect. Seersucker should not be confused with fabrics having puffed effects created by chemical finishes, such as plisse or embossing, which are much less durable. 

Hand-Woven Tapestries 
Tapestries woven by traditional methods differ from jacquardwoven fabrics having the appearance of a tapestry in that the traditionally woven tapestries are made using hand techniques. Jacquard-woven tapestry fabrics generally use repeated patterns of finite size. Traditional tapestry weaving is used to produce enormous fabrics that can form one large picture. Tapestry weaving may be compared to painting with yarn. Since it is basically a hand technique, tapestry is made on an elementary loom. 

In the weaving of European tapestries, the loom followed the basic form of the two-bar loom. The loom was set up either vertically or horizontally, and warp yarns were measured and affixed to the loom. Filling yarns were prepared in the appropriate colors. The design of the tapestry was first worked out in a drawing, or cartoon, as it was called. The artist who created the drawing may have been one of great stature, and painters such as Raphael and Rubens served as designers of sixteenth- and seventeenthcentury tapestries. The cartoon was sometimes traced onto the warp yarns. In other instances it was mounted behind the loom, and the tapestry weaver looked through the warp yarns to the design, following the plan of the drawing. The tapestry was woven with the wrong side facing the weaver. Sometimes a mirror was set up beneath the tapestry so that the weaver could check the progress on the right side. The various colors of yarns were wound onto sharp, pointed bobbins that were introduced into the warp, and the weaver proceeded to fill in the area of that particular color. When the weaver reached the end of one color, a new bobbin was used for the next section. This created a problem, because as the weaver worked back and forth in a particular segment of the 

design, the yarns of one color did not join with the yarns of the adjacent color. This produced slits in the fabric at the place where each new color began. Sections of the tapestry could be sewn shut, but this caused the fabric to be weaker at the spots where the fabric was seamed together. Two other methods were also used to prevent the formation of slits. Where the color of one section ended and another began, both the old and the new color could be twisted around the same warp yarns. This system worked well except that it created a slightlyindistinct or shadowy line. Where clear, well-defined lines were required, the yarns of adjacent colors were fastened together by looping one yarn around the other.In traditional tapestry weaving, all the warp yarns are completely covered by filling yarns, so it is the filling yarns that carry the design. The warp yarns serve only as the base.

Satin Weave; Produce woven fabric with Warp faced satin weave and Weft-faced Satin (Sateen) weave

Weft-faced Satin (Sateen) weave




It is characterized by long floats on the surface of the fabric. In basic construction, the satin weave is similar to twill weave but floats in satin fabric may cross from four to twelve yarns before interlacing with another yarn. No pronounced diagonal line is formed on the surface of the fabric because the points of intersection are spaced in such a way that no regular progression is formed from one yarn to that lying next to it. When warp yarns form the floats on the face of the fabric, the fabric is a warp-faced satin. They are usually made from filament yarns and are called SATINS. When filling yarns float on the face, the fabric is a filling-faced satin. This is called SATEEN WEAVE Satin-weave fabrics are made by allowing yarns to float over a number of yarns from the opposite direction. Interlacing are made at intervals such as over four, under one (using five harnesses); over seven, under one (eight harnesses); or over eleven, under one (twelve harnesses). Floats in satin fabrics may cross from four to twelve yarns before interlacing with another yarn. No pronounced diagonal line is formed on the surface of the fabric because the points of intersection are spaced in such a way that no regular progression is formed from one yarn to that lying next to it.When warp yarns form the floats on the face of the fabric, the fabric is a warp faced satin. 

When filling yarns float on the face, the fabric is a filling faced satin. Satin-weave fabrics made from filament yarns are called satins; those from spun yarns are sateen. Most warp-faced weaves have filament yarns because filament yarns do not require a tight twist to serve as warp yarns, whereas cotton, being a staple fiber, must be given a fairly high degree of twist if it is to serve as a strong warp yarn. Therefore, sateen fabrics are usually filling faced, although some warp sateens are made. 

Warp faced satin weave Weft faced satin










Satin-weave fabrics are highly decorative. They are usually made from filament yarns with high luster to produce a shiny, lustrous surface and tend to have high fabric counts. They are smooth and slippery in texture and tend to shed dirt easily. The long floats on the surface are, of course, subject to abrasion and snagging. The longer the float, the greater the likelihood of snags and pulls. Satins are often used as lining fabrics for coats and suits because they slide easily over other fabrics. The durability of satin-weave fabrics is related to the density of the weave, with closely woven, high count fabrics having good durability. Satins made from stronger fibers are, of course, more durable than those made from weaker fibers. 

The following are some names given to satin fabrics. 
1. Antique satin, a satin made to imitate silk satin of an earlier period, often uses slubbed filling yarns for decorative effect. 
2. Peau de soie is a soft, closely woven satin with a flat, mellow luster. 
3. Slipper satin is a strong, compact satin, heavy in weight. It is often used for evening shoes. 4. In crepe-backed satin, loosely twisted, lustrous warp yarns are combined with tightly twisted, creped filling yarns. The floats on the surface are created by the warp, so that the face of the fabric is chiefly made up of warp yarns with a satin appearance, whereas the back of the fabric is made up largely of tightly twisted filling yarns that produce a crepe or rougher surface texture with a flat, less shiny appearance.

• Satin weaves are lustrous because of more yarn showing on surface 
• Fabric is comparatively weaker due to long floats, which represents minimum of interlacing. 
• Satin weave has a distinctive reversible side 
• Excellent drapability 
• Easily to slip on and off the fabric i.e. the fabric is smooth to touch that’s why used as lining material also 
• Ex: Satin, Sateen, etc.

Monday, January 7, 2013

Selvags, Two edge of woven fabric

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Selvags
Selvage is one of the most important parts of woven fabric. It plays vital roles during weaving. Selvage could be defined as the two end of the woven fabric width or the edge of woven fabric. This is different from main fabric. Most of the selvage made with strong thread like nylon thread. It holds the woven fabric and helps to maintain the shape of fabric. It takes all the pressure of weaving machine and protect the fabric from damage.
Selvags (Selvedges) As the shuttle moves back and forth across the width of the shed, it weaves a self-edge called the selvage, or selvedge, on each side of the woven fabric. The selvage prevents the woven fabric from raveling. 
It is usually made more compact and stronger than the rest of the woven fabric by using more or heavier warp yarns or by using a stronger weave. There are different kinds of selvages. The kind of selvage used depends upon economy of production and the expected use of the woven fabric. 

Plain Selvages 
These selvages are constructed of the simple plain weave with the same size yarn as the rest of the fabric, but with the threads packed more closely together. Such selvages are fairly durable and firm. 

Tape Selvages 
The tape selvages are sometimes constructed with the plain weave but often are made of the basket weave, which makes a flatter edge. Tape selvages are made of heavier yarns or ply yarns, which provide greater strength. 

Split Selvages 
Split selvages are made by weaving a narrow width fabric twice its ordinary width with two selvages in the center. The woven fabric is then cut between the selvages, and the cut edges are finished with a chain stitch or hem. 

Fused Selvages 
These selvages are made on fabrics of thermoplastic fibers, such as nylon, by heating the edges of the fabric. The fibers melt and fuse together, sealing the edges. This technique is sometimes used to split wide fabrics into narrower widths. 

Leno Selvage 
The leno selvage is used on some shuttle less looms as well as weaving machine. The construction utilizes a narrow leno weave, which locks the cut ends along the fabric edge. A loose weave generally requires a tight leno selvage, whereas a light weave may have a leno selvage with less tension. 

Tucked Selvage 
The tucked selvage is a technique used on some shuttle less looms. A device is used to tuck and hold the cut ends into the fabric edge. The construction of the selvage is dependent upon the particular weave and a number of other factors. A formula for weaving the tucked selvage considers fiber density, the diameter of the yarns (which is also affected by twist, ply, and count variation), as well as the yarn diameter balance, or ratio of the diameter of the filling yarn to that of the warp yarn in effect, if the diameter of the filling yarn is finer than the diameter of the warp yarn, fewer fillings can be inserted in themfabric selvage, because the warp intersection requires more space between the fillings than one diameter of the filling.
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Sunday, January 6, 2013

Manufactured Fibres or Textile Fiber manufacturing

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The producer of natural fibres and the producer of manufactured fibres are engaged in two very different businesses. The farmer who raises cotton, the rancher who herds sheep or the grower of silkworms is trying to produce a maximum quantity of fibre from animal or vegetable sources. The grower may attempt to improve the quality of the seeds or breeding stock but is limited in production by natural factors. If the demand for the product increases or decreases, the grower cannot, like the manufactured fibre producer, simply increase or decrease the short-term supply of fibre.

Manufactured Fibres
The term-manufactured fibre describes a fibre produced commercially through regeneration from natural materials or synthesized from chemicals. Trade associations in the manufactured fibres industry may be industry wide or specific to particular fibres. The American Fibre Manufacturers Association, Inc. (AFMA) is the trade organization for the manufactured fibres industry, conducting many of the same kinds of promotional activities as described for the natural fibres associations.

AFMA always uses generic fibre names-such as polyester, nylon, rayon, and so on-in printed materials, while its individual fibre producing members concentrate on their trademarked fibre names, such as DuPont’s Dacron@ (polyester) or Wellman’s Fortrel@ (polyester). Producers of particular fibres may also join together to form fibre-specific trade associations. The Acrylic Council, the Polyester Council, and the American Polyolefin Association are examples of fibre-focused trade associations.

Production in the manufactured fibres industry differs from the production of natural fibres in a number of ways. While the manufactured fibres industry must depend on available supplies of the raw materials from which fibres are made, this industry is not dependent on natural forces that regulate the supply of fibre. A great many manufactured fibres are made from materials derived from petroleum, and therefore supplies and costs of raw materials may be affected by changes in the price of oil. Manufacturers can regulate production according to supply and demand. Manufacturers can also help to create demand for increased quantities of fibre products through advertising and other publicity.

Many manufactured fibre producers and firms are, or were originally, chemical companies. The fibre manufacturer generally sells the fibres produced to a firm that will make yarns and/or fabrics. These fibres may be sold as unbranded products or commodities. When fibres are sold in this way, the purchaser has no obligation to the fibre manufacturer to produce a product of any specific quality. Products must meet no minimum standards. In short, the buyers can do whatever they wish with the fibres they have purchased. Other fibres may be sold as trademarked fibres. The manufacturer owns the trademark, which is denoted by placing either the symbol @ or TM after the trademarked name. Trademarked names are always capitalized-for example, Micrell@ polyester. The owner of a trademark can bring court action to prevent unauthorized use of the trademark.

When the fibre manufacturer’s trademarked name is carried by the finished product, the fibre manufacturer has some control over the quality of the fabric, although it is still possible that a poorly made garment could be constructed from the fabric. One advantage to the fabric and garment manufacturers of buying a trademarked fibre is that they can capitalize on the publicity and promotional materials distributed by the fibre manufacturer. Licensed trademarked fibres are sold only to those manufacturers whose fabrics meet the standards established by the fibre manufacturer. Standards may be set in regard to the construction of fabrics, the manufacture of apparel or other products, and, in blends or combinations of two or more fibres, the appropriate proportion of fibres to be combined. As an alternative to trade marking, some fibre companies assign certification mark names to yarns or fabrics made from their fibres. Such designations require that the items identified with the certification mark meet criteria established by the fibre manufacturer.

Not only do the fabric and garment manufacturers benefit from customer familiarity with the brand name of the fibre, but the fibre manufacturer often shares the costs of advertising or mounts intensive publicity campaigns to promote the fabric, the final product, and even retail outlets where the products are sold.

The interest of manufactured fibre producers in their products does not end when the fibre is sold. Because techniques for spinning and fabricating manufactured fibres may not be uniform for all fibres, the fibre producer provides technical assistance to the fabric manufacturer. Technical bulletins are published that recommend the most effective ways of processing fibres. Consultants from the fibre companies provide information about new developments in textile machinery and finishing. Research and development in fibre-producing companies is often focused on more effective ways of handling manufactured fibres during fabrication.

Fibre producers assist manufacturers of fabrics, garments, or other products to locate sources of yarns and fabrics. The marketing department of a fibre-producing company also maintains a library of fabrics that can be used by manufacturers and their designers.

A wide variety of other services is offered to the direct customers of the fibre companies and to the general public. Exhibits of current products are presented, often at trade and professional meetings. Educational materials for schools, retailers, and consumers are prepared and distributed. Retail stores may be assisted in promoting trademarked products through fashion shows, publicity materials, or cooperative advertising in which the fibre producer pays some part of the advertising costs. Fashion consultants may be available to assist the designers of fabrics, clothes, and furnishings.

Many of these activities are part of an organized advertising and public relations program. In addition to the services offered that result indirectly in publicity and goodwill for the company, direct advertising is also utilized. Besides advertising cooperatively with manufactures of retail products and retail stores, fibre companies also advertise in publications ranging from those for the trade to general magazines. Research and development (often abbreviated as R & D) is an important function in most large textile fibre companies.

Researchers are constantly looking for new fibres, fibre modifications, and improvements in processing at all steps of manufacture. The whole synthetic fibres industry might be said to have grown out of the research and development program at the chemical company Dupont, for it was in this program that W. H. Caruthers first synthesized nylon.
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Industrial Textiles; The Major Textile Production Segments

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Industrial Textiles 
Most consumers are not aware of the segment of the textile industry known as industrial textiles, even though they encounter these products every day. Industrial textiles is the most commonly used name for textile applications in agriculture, air and water filtration, architecture, automobiles, banners and flags, casual furniture, environmental protection, earth stabilization, medical products, recreational products, and transportation vehicles. Apparel items in this category are those in which performance is paramount: clean room garments, protective gloves and clothing for industry and farming, industry garments that don’t develop electrostatic charges (World of Industrial Fabrics n.d.) 

Other descriptive terms applied to this segment of the industry are industrial fabrics, technical textiles, engineered fabrics, and technical fabrics. Industrial textiles may be woven, knitted, or nonwoven, often of manufactured fibers. Fashion is not a factor in industrial textiles, but instead such functional characteristics as strength, stability, chemical resistance, and weight are likely to be important. Examples of industrial textiles range from small products such as filters and auto safety belts to enormous structures such as roofs, tents, and storage tanks. Roofs and other building structures encompass the field of textile architecture, a growing area of interest that combines engineering and art design. Consumers of industrial products include the construction, mining, sanitation, and transportation industries; medicine; and the military. 

The industrial fabric segment of the textile field has grown rapidly in recent years. Some of the more dramatic examples of progress in textile technology have come in this area, particularly fiber-reinforced composites for the aerospace industry and geotextiles. Geotextiles are textiles used in soil and soil-based structures such as roads, dams, and erosion-control products. 

The Major Textile Production Segments 
The textile industry is segmented into three large groupings: Apparel, the textiles used in clothing; interior furnishings (also called home fashions) the textiles used in furniture, bath, kitchen and bed; and industrial, the textiles used in such items as luggage, flags, boat sails, gauze bandages, dust filters, and so on. The market is divided into approximately 40 percent apparel, 40 percent interior furnishings, and 20 percent industrial and miscellaneous consumer-type products. 

The textile industry uses many different raw materials and many steps in the process of manufacturing a finished textile material. Each segment in the pipeline is not only involved with production, but also with buying the product of a previous producer. Thus, the entire process from fiber to consumer (or other ultimate buyer) involves the coordinated activities of many firms and many individuals within each firm. The following sections describe the major production segments, each of which is discussed in much more detail later in this book. 

It takes almost a year from the time a fiber supplier starts delivering fibers for yarn manufacturing until the completed garment is ready for sale in the retail store. The fiber shipments stop about four months before the start of the retail season. The yarn manufacturers begin delivering their yarns to the mills about nine months before the garments are to be sold in the retail stores and stop about two months before. The finished fabrics start to be shipped to the garment manufacture about six moths before and continue to be sold into the retail-selling season. 



Some apparel manufactures start cutting fabrics four months before the season and many continue to cut after the season has begun. There are two main retail-selling seasons for apparel. They are fall and spring. The former starts about August first and the latter begin about February first. The other seasons include summer and Holiday.
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Textile Terms, Important Textile term and definitions

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Fibres 
Fibre is one of the most important textile terms. Fibers are the smallest part of the fabric. They are fine, hair-like substances, categorized as either natural or manufactured. Cotton, which grows on a plant, and wool, which is shorn from a sheep, are two examples of natural fibers. Manufactured fibers are created from chemicals and include acrylic, nylon, and polyester. They are produced by chemical companies, such as E.I. DuPont de Nemours & Company and Hoechst Celanese Corporation. 


Yarns 

The term yarn means the raw material of fabric. Most textile materials contain yarns, which are continuous thread-like strands composed of fibers that have been twisted together. (Felt is an example of a material made directly from fibers but containing no yarns). There are various types of yarn, from flat and dull to slubby and lustrous. Each one could be made from different fibers. 


Fabrics

The definition of fabric is very simple. Most fabrics are made from yarns and are either woven or knitted. The companies that make fabric are called mills; Springs Industries and Milliken & Company are two of the largest mills. The range of fabric types and weights is tremendous, fulfilling a variety of consumer demands. 

Dyeing and Printing 
Color is usually applied to the woven or knitted fabric by either Dyeing or Printing. The term dyeing is the process for imparting a solid color to textiles (blue, green, red, etc.). The term printing is the process of imparting designs to textiles (dots, floral, stripes, etc.). The purpose is to make the fabric more appealing. These operations are performed in dye plants or pint plants, and the companies are called dye houses or pint houses. 


Finishing

Most fabrics need additional treatments termed as finishes before they can be used. For example, special chemicals are used to make a fabric water-repellent and suitable for a raincoat. A special brushing machine is required to make the fuzzy surface on flannel fabrics. The processes are done in finishing plants whose facilities are most often part of dye plants or print plants. After finished fabric has been produced, it is usually used by other manufacturers to make such items as blouses, draperies, tents, or automobile tires. A particular fabric might be used for several different articles, such as a dress, a shirt, and curtains Frequently, the same fabric that is shipped to the apparel or interior furnishings manufacturer is also sold to a retail store for direct sale to home sewers. 


Automation and Computer Use 

As with practically every other endeavor of our lives, computers and electronic technologies have had a tremendous impact on textile-related industries and businesses. Computerization has made a difference in design, decision-making, communication, and process control in manufacturing. Feedback on consumer preferences and product sales is readily available to fiber and fabric producers, apparel manufacturers, dyers, and finishers. The computer has become a routine tool for apparel and interior designers and for product developers; and control of manufacturing processes is increasingly a job for computer programmers. 

The textile and apparel industries have formed an organization called the Textile/ Clothing Technology Corporation or (TC) 2. The purpose of TC2 is to conduct research about applications of electronic technology in the textile and apparel industries and to educate executives, engineers, technologists, and educators about automated systems, their potential, and their use. (TC) 2 is funded jointly, largely by matching grants, by the industry and the federal government. 


Computer-Aided Design (CAD)

Computer-aided design (CAD) in textiles is applied to the design of yarns and fabrics and to coloration. In those firms that are vertically integrated, CAD may also be applied to apparel design and manufacture. Programs allow the textile designer to develop and modify designs interactively, speeding up the process and providing electronic links to production. 

Recent techniques in three-dimensional (3-D) imaging enable simulation of the actual fabric structure and texture on screen and advances in color printing allow better reproduction of the design on paper or other media. Designs can be scanned into the system and then modified or redesigned. CAD applications for knitted fabrics and garments have advanced rapidly. A variety of CAD systems that interface design and construction in the production of woven fabrics and knitted goods are currently available and in use. New technologies have also been developed to predict the drape of fabric on 3-D moving figures, integrating the fabric and apparel design stages. This involves mathematical modeling using fabric behavioral properties. The fabric’s physical characteristics are separated from the surface design so that different types of motion can be applied to any design (Gray 1994; Gray 1998). (See Figure 1.10.) This, along with the textile design capabilities described above, allows merchandisers to create “virtual samples” for customers (Ross 1998). Computer figures are also used in 3-D scanning, a development in CAD, that is moving the apparel manufacturing customization, which is the mass production of custom garments. Women’s jeans produced through such a process were first marketed in November 1994 (Rifkin 1994).
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Saturday, January 5, 2013

Textile Finishing; Light Reftectant and Light Resistant Finishing

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Textile finishing is complex procedure. There are two types of fabric finishing. Light-Reftectant Finishing and Light-Resistant Finishing are one kind of chemical finishing. Those fabric finishing process are used to make textiles lightproof for particular end use. Some of the chemical change their form in presence light. In that case the chemical must preserve in light protected area. We can easily produce ultraviolet protected fabric using the light reflectant and resistant finishes. Ultraviolet protection is now being built into fibers and fabrics. 


Light-Reftectant Finishes 

Light-reflectant finishes are created by the application of microscopic reflective beads to the surface of a fabric. The increased number of persons who jog or ride bicycles after dark is probably responsible for the application of this finish to a variety of garments for sports and to other items such as backpacks. A reflective finish called Scotchlite is produced by the 3M Company. The manufacturer notes that the finish does not alter the color or appearance of the garment by day, but after dark the fabric “lights up” when directly in the path of the lights of an oncoming vehicle. 


Light-Resistant Finishes

Many textile fabrics are deteriorated by exposure to sunlight, so attempts have been made to protect fabrics from light damage. Of all the types of rays in the sun’s spectrum, ultraviolet rays are the most destructive of fibers. Although antilight finishes have yet to be perfected, those that are being tried either coat the fabric or impregnate the fibers with materials that absorb ultraviolet rays but are not themselves damaged by or removed by exposure to these rays. Such finishes are particularly important in olefin fabrics, which are degraded by sunlight unless ultraviolet stabilizers are added. Such additives to olefin fibers are permanent and are not lost during usage. 

Synthetics that have been delustered with titanium dioxide are especially subject to damage from sunlight. This chemical apparently accelerates damage to the fiber and fading of dyes. The addition of certain chemical salts to the melt solution before spinning can ameliorate this problem. The relationship between exposure to the ultraviolet light of the sun and skin cancer is well known. Many people assume that fabrics prevent exposure to any part of the body that is covered; however, research shows that fabrics do allow passage of ultraviolet light. Knitted fabrics, which usually have a more open structure, generally allow more ultraviolet light through than woven fabrics; lightweight summer fabrics allow more ultraviolet light to reach the skin than heavier fabrics with more opaque yarns. Ultraviolet protection is now being built into fibers and fabrics. Most of the techniques are proprietary processes, so details of how the protection is provided are limited. Kuraray, a Japanese firm, produces Esmo, a polyester staple fiber to which powdered ceramics have been added to absorb and reflect ultraviolet rays. A similar fiber called Aloft is produced by the Japanese firm Toray, and other Japanese firms produce fabrics that are given special protective finishes Australian researchers have developed a chemical finish called Rayosun that is said to be washfast, colorfast, and lightfast. The finishing material contains a “two part molecule,” one part of which absorbs ultraviolet rays while the other part reacts with the fabric, thereby making the finish durable (Sun-proof clothing 1993, 72).
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