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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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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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

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.