Bonded Fabric

Bonded fabric is a combined structure of fabric that is being created by joining two set of fabric. This attachment of two fabrics can be made with adhesive or thin bonding fabric with low melting point without any major changes of finished fabric thickness. Here a face or shell fabric is joined with backing fabric. Artificial leather products can be a good example of this type of fabric. Bonded fabric also used in design purposes and fabric stabilization.

An aqueous acrylic adhesive is used for joining bonded fabric. A latex adhesive such as, acrylate, a vinyl chloride or vinyl acetate or thermosetting resin also being used for this purpose. This bonding strength between these two layer fabrics is the main thing where the end uses of the finished product depends on.

Fabric Bonding Procedure:
There are two common methods for attaching fabric to fabric.
1. Wet adhesive method
2. Flame foam method

Wet adhesive method:
· An adhesive liquid is applied to the back of the face fabric.
· Face fabric is set on backing fabric and passed together between the heated rollers.
· Thus, the heat fixes the adhesive between two fabrics and makes the bonded fabric.

Flame foam method:
· Here, a thin layer of polyurethane foam is used to attach two set of fabrics
· First, polyurethane foam is melted a little by passing it over a fire/heat.
· Then this melted foam is set between two layers of fabric just like a sandwich.
· After that, when the foam got dries, it attach the two layers of fabric.

Actually the foam in the bonded fabric is so thin (around 0.010 inch). That why, It doesn’t make any significant changes on the thickness of the finished fabric. By this method fabric may got stiffer than the wet-adhesive method. Sometime foam may appear of the surface of the fabric. That’s why it is not better not to use this method with open-weave fabrics.

Advantages
· This bonded fabric is much cheaper in price
· This fabric is machine washable
· Fabric doesn’t crease easily

Crimp based on warp and weft yarn on fabric

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CRIMP
When warp and weft yarns are interlaced in a fabric they follow a WAVE or CORRUGATED configuration, the plane of the weave being substantially perpendicular to that of the fabric. This WAVINESS OF YARN is called CRIMP of yarn and is expressed quantitatively either as a fraction, c or as a percentage, c per cent:

c = (Ly - Lf)/Lf; and, c per cent = (Ly – Lf) x 100/Lf

Where Ly = the un crimped length of the yarn, and, Lf = its extent in the fabric.

The expression c = (Ly – Lf) / Lf may be written as:

c = Ly / (Lf - 1), from which

(1 + c) = Ly / Lf;

where (1 + c) is called the crimp ratio. It is useful in fabric calculations.

MATH: Calculate the length of warp required to weave 160 yds. of cloth if the warp crimp is 12 percent.

We know,
Lf = 160 yd. and c1 percent = 12; so c1 = 0.12, where c1 is fractional warp crimp, and

Ly = Lf (1 + c) = 160 x 1.12 = 179.2 yd.

So, to prepare 160 yds of fabric 179.2 yds of warp is required.

MATH: What length of cloth can be woven from 800 yds of warp if the crimp is 8 percent?

We know
Ly = 800 Yd., and c1 percent = 8, so c1 = 0.08; where c1 is fractional warp crimp, and

Lf =Ly/(1+c) = 800/1.08 = 740.8 yds.

So, 800 yds. of warp will weave 740.8 yd of cloth.

When the shuttle inserts the weft in the open shed, the weft is un crimped, and each pick has a length Ly, which is equal to the width occupied by the warp in the reed. This is called the reed width. When it is beaten up by the reed and incorporated into the cloth at the cloth fell, the weft attempts to crimp under the scissors-like pressure exerted by the warp threads. At this stage, it is prevented from crimping freely by the temples, whose function is to hold out the cloth near the fell to reed width, so as to prevent excessive abrasion of the warp threads near each selvedge by the reed. As the cloth moves forward towards the breast beam, it leaves the temples and is free to contract to a length Lf, called loom-state width. The weft is now crimped. We have three variables, i) reed width, ii) the width of the loom-state cloth, and iii) the weft crimp in the loom-state cloth. If we know two of these variables, the third can be calculated as illustrated by the following examples.

MATH: Calculate the reed width required to give a cloth with a loom-state width of 38”, if the weft crimp in the loom-state cloth is known to be 6 percent.

We know
Lf = 38”, and c2 percent = 6; so c2 = 0.06, where c2 weft crimp, and

Ly = Lf (1 + c) = 38 x 1.06 = 40.28”

which is the required reed width.

MATH: Calculate the loom-state cloth width if the reed width is 60”, and the weft crimp is known to be 9 percent.

We know

Ly = 60” and c2 percent = 9; so c2 = 0.09, where c2 is weft crimp, and

Lf = Ly/ (1+c) = 60/1.09 = 55.05”

which is loom-state cloth width.

MATH: Calculate the weft crimp in the loom-state cloth if the reed width is 44” and the loom-state cloth width is 40”.

We know

Ly = 44”, and Lf = 40”.

Therefore (1+c) = Ly/Lf = 44/40 = 1.10, so c2 = 0.10 and c2 percent = 10

which is the weft crimp.

In any of the above examples we could substitute the width of the finished cloth for that of the loom-state cloth, provided that we also substitute the weft crimp in the finished cloth for that of the in the loom-state cloth. The calculation would be valid, if no unrecoverable shrinkage had occurred during finishing, but not, for example for a milled woolen cloth.

EFFECT OF CRIMP OF YARN ON FABRIC PROPERTIES
a) RESISTANCE TO ABRASION: With the increase of crimp %, the abrasion resistance will also increase
b) SHRINKAGE: With the increase of crimp %, shrinkage of fabric will decrease.
c) FABRIC BEHAVIOUR DURING TENSILETESTING: With the increase of crimp%, breaking load of fabric will also increase.
d) FABRIC COSTING: With the increase of crimp%, fabric costing will also increase. Because crimp decrease the length of yarn as a result more yarn will be needed for fabric manufacture in case of more crimp on yarn.
e) FAULTS IN FABRIC: If there is variation of crimp in the threads then the following faults may be found in fabric; A) Reduction in strength may occur, and B) Stripes will be seen in yarn dyed cotton fabric.
f) FABRIC DESIGN: To achieve satisfactory appearance and required shape in finished fabric control of crimp in warp and weft yarn is necessary..
g) FABRIC STIFFNESS: If crimp is increased then stiffness of fabric will decrease.
h) ABSORBENCY: With the increase of crimp % absorbency of the fabric will increase.
i) DIMENSIONAL STABILITY: Dimensional stability will decrease with the increase of crimp%.
j) FABRIC HANDLE: If crimp is increased then the fabric will be soft in handle.
k) DYE TAKE-UP: With the increase of crimp the take-up percentage of dye-uptake will also increase.

Wish You Good Luck..................................
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Cover Factor of Fibre, Yarn and Fabric

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CONCEPT OF SIMILAR CLOTH
Fibre or raw materials of the two cloths may be same but they can differ on other factors, such as:-
i) The yarn count may be different.
ii) The ratio of yarn count in warp and weft may differ.
iii) The warp ratio of yarn spacing may differ.
iv) The average of yarn spacing may differ.
v) The weave design may differ.
vi) The amount of twist in yarn may differ.

If there is similarity in COVER FACTOR of two cloths but they differ in such points as mentioned above then they are called similar cloth.

COVER FACTOR
Cover is the degree of evenness of thread spacing. Good cover gives the effect of a uniform plane surface & it can not be obtained with hard twisted yarn. In case of woven fabric cover factor is a number that indicates the extent to which the area of a fabric is covered by warp and weft threads. For any fabric by introducing suitable numerical constants its evaluation can be made in accordance with any system of counting. It is denoted by k.

Mathematically,

        k = d / p;

where, d₁ = Warp dia; d₂ = Weft dia; P₁ = Warp spacing; P₂ = Weft spacing; k₁ = Warp cover factor, and k ₂ = Weft cover factor.

     

So, k₁ = d₁/P₁    &    k₂ = d₂/P₂

Therefore, Fabric Cover Factor =  k₁ + k₂.

The ratio of yarn diameter to yarn spacing, d/p, is a measure of the relative closeness of the yarns in the warp or weft of a woven fabric. This ratio also expresses the fraction of the area of the cloth covered by the warp or weft yarns. We may therefore call it the fractional cover,  i.e.

                      Fractional cover = d / p.

Substituting Peirce’s estimate of yarn diameter, d = 1/28 √N, we have 

d / p= [1/(28√N) x1/p]

 But 1/p = n, where n = threads/in., so

 d / p= n/(28√N) ……………………………… (6)

Now d/p has a value of 1.0 when the yarns are just touching. Peirce multiplied eq.(6) by 28 to eliminate the numerical constant, 28, and defined the result as the ‘coverfactor’, K.

Cover Factor, K  = n /  √N  ……………………………………………..(7)

Because we have multiplied by 28, cover factor as defined in eq.(7) has a value of 28 when the yarns are just touching. The relative yarn spacing corresponding to various cover factors are shown below:

It is usual to calculate separate cover factors for the warp and the weft. Using the suffices 1 and 2 for warp and weft, we have

      Warp Cover Factor, K₁ = n₁ / √N₁ and

      Weft Cover Factor, K₂ = n₂ / √N₂.

The sum of the warp and weft cover factors is known as cloth cover factor, Kc.  It is customary and more informative, however, to state the warp and weft cover factors separately. Just as twist factor enables us to compare the relative hardness of twist in yarns of different counts, so cover factor enables us to compare the relative closeness of the yarns in different fabrics.

Math related to cover factor

Compare the relative closeness of the warp yarns in the following two plain cloths; (a) 16s cotton; 50 ends/in; and (b) 36s cotton; 84 ends/in.

We have the cover factor for cloth (a), K₁ = 50 / √16   = 12.5.

And for cloth (b) cover factor, K₂ = 84 / √36   = 14.0

So the ends are more closely spaced in cloth (b) than in cloth (a)

MATH:- Calculate the warp and weft cover factors for the following fabric: 60 denier nylon x 48s worsted; 96 x 72.

      60 denier = 5315/60 = 88.57s cotton count.

So, K₁ = 96 / √88.57   = 10.2

       40s worsted = 48 x 560/840 = 32s cotton count.

So, K₂ = 72 / √32   = 12.7

GENERAL FORMULA FOR CALCULATING COVER FACTORS

   Indirect systems                                              direct systems.

      K = cn/ √N                                                    K = cn √N

Where N is the yarn number in the particular system.

System                Value of c                          System          Value of c

Cotton                     1.0                                     Denier        0.01375

Worsted                  1.228                                 Tex             0.04126

Linen lea                 1.667                                 lb/spdl        0.2422

MATH: Calculate the cover factor corresponding to 80 threads/in. of 100 denier. 

From the table constant for the denier system is  0.01375.

Therefore, K  = 0.01375 x 80 x √100  = 11.0

MATH: How many threads/in. of 5 tex nylon are required to give the same cover factor as 90 threads/in. of 2/100s cotton?

Since the equivalent singles count of 2 /100s is √50 s.

Therefore,

                            K  = 90/ √50.

So, K = 12.7  = 0.04126 x n √5

 Therefore  the number of threads required

n=12.7/0.04126 x √5 = 138 threads / in.         

Thus required thread/in is 138 of 5 tex to give the same cover factor as 90 threads/in. of 2/100s cotton.

This problem can also be solved with reference to the formula for calculating cover factor.

     5 tex  = 590.5 / 5  = √118 s cotton count.

As before, K  = 12.7  = n/ √118.

Therefore n = 12.7 x   118   = 138 as before.

Wish You Good Luck..................................
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Nonwoven Fabrics | Introduction and manufacturing process of nonwoven geotextile fabrics

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Nonwoven Fabrics 

Techniques by which fabrics are made directly from fibers, bypassing both spinning and weaving, have been used for centuries in the production of felt and bark cloth is called nonwoven fabric. It is also called nonwoven geotextile fabric because it is one kinds of geotextile. With the development of manufactured fibers, and, in particular, the synthesis of thermoplastic fibers, technologies have evolved that have made possible the large-scale production of non-woven fabrics. The first non-woven consumer product, an interlining fabric for the apparel industry, was introduced in 1952. Marketed extensively for both durable and disposable items, nonwoven fiber webs range from disposable diapers to blankets, from industrial filters to tea-bag covers. 

Nonwoven fabrics are textile structures “produced by bonding or interlocking of fibers, or both, accomplished by mechanical, chemical, thermal or solvent means and combinations thereof” (ASTM 1998). This excludes fabrics that have been woven, knitted, or tufted. The Association of the Nonwovens Fabrics Industry (lNDA) in the United States and the European Disposables and Nonwovens Association (EDANA) help to further define what may be called a nonwoven fabric Oirsak and Wadsworth 1999). Over 50 percent of the weight of a non woven must be comprised of fibers with an aspect ratio (length to diameter ratio) of 300. This excludes paper products that are normally made of extremely short fibers. In additi”on nonwovens must have a density less than 0.4 grams per cubic centimeter, and felted fabrics are usually much heavier. 

American Fabrics (1974) magazine recommended that nonwoven fabrics be classified as durable products or disposable products. They defined a durable product as “one which is multi-use. It is not manufactured to be thrown away after a single application” (p. 40). Examples of this type of product are blankets, carpet backings, and furniture padding. Disposable products were defined as “made to be disposed of after a single or limited number of uses”. These are exemplified in disposable diapers, towels, or tea-bag covers. American Fabrics pointed out that some items are disposable not because of their durability but because of their purpose. Medical gowns, for example, or airplane and train headrests, might withstand multiple use, but for sanitary reasons they have limited use periods. 

Manufacture of nonwoven fabric

There are two steps involved in manufacturing nonwoven fabrics: 

(1) preparation of the fiber web and 

(2) bonding of the fibers in the web. 

A number of possibilities exist for each step, and in addition, the two stages may be distinct or can be carried out as a more or less continuous process. 

Fiber Web Formation Staple fiber webs are produced by either dry firming or wet firming. Dry-forming processes are carding, also called dry laying, and air laying. Carded webs are made in a manner similar to the process for felt webs and slivers for yarn spinning. Thicker webs can be built up by layering the carded webs. In air laying, the fibers are opened, suspended by air, and then collected on a moving screen. The wet laid process is similar to paper making in that a mixture of fibers in water is collected on a screen, drained, and then dried. 

Webs can also be made by the direct extrusion processes of spunbonding and melt blowing. Spunbonded fabrics are manufactured from synthetic filament fibers. Continuous filaments are formed by extrusion through spinnerets, and the filaments are blown onto a moving belt where they form a web. As the still hot and partially molten filaments touch, they bond. Polymers most often used are polypropylene and polyester. Spun bonded fabrics are strong because of the filament fibers and are not easily torn. They are used for a wide variety of products ranging from apparel interlinings, carpet backing, furniture and bedding to bagging and packing material. Spunbonded fabrics may be used in geotextiles to control erosion or in constructing roads. 

Some spun bonds made from olefins are used as a tough, especially durable substitute for paper in wall coverings, charts, maps, tags, and the like. Melt blowing also forms fabrics directly from fibers, but it differs from spun bonding in that molten fiber filaments are attenuated and broken into short lengths as they exit from the spinnerets. Cool air distributes the fibers onto a moving screen. 

As the fibers cool they bond, forming a white, opaque web of fine fibers. Because the fibers in melt-blown nonwovens are fine, the fabrics make good filter materials. Specialty products can also be made by layering spun bonded and melt blown fabrics or by entrapping absorbent fibers or other materials within the melt blown structure.

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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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SELECTION OF DYEING PROCESS FOR DYEING OF TEXTILE MATERIAL

SELECTION OF DYEING PROCESS:

Even dyes that belong to the same class can have differing degrees of colorfastness to the same condition, so that the consumer has no real guarantee of color permanence unless a label specifies that a particular fabric is colorfast. Dye performance labeling is not required by any form of legislation or regulation. Some manufacturers do, however, include colorfastness information on labels. Such labels will generally describe the conditions under which the fabric is colorfast, such as “colorfast to laundering, but not to chlorine bleaching” or “colorfast to sunlight.” A few terms may be found on labels that carry an assurance of colorfastness, such as trademarks that have been applied to solution-dyed synthetic fibers. The colorfastness of one class of dyes, the vat dyes, is so consistently good for laundering that the term “vat dyed” on labels has come to be accepted as an assurance of good colorfastness.

Textile may be dyed at any stage of their development from fiber into fabric or certain garments by the following methods:

• Stock dyeing, in the fiber stage

• Top dyeing, in the combed wool sliver stage

• Yarn dyeing, after the fiber has been spun into yarn

• Fabric/ Piece dyeing, after the yarn has been constructed into fabric

• Solution pigmenting or dope dyeing before a manmade fiber is extruded through the spinneret

• Garment dyeing after certain kinds of apparel are knitted /Woven

Stock Dyeing:

Mass Coloration

Mass coloration is the addition of color to manufactured fibers before they are extruded. These fibers have been variously known as spun-dyed, solution-dyed or doped.:; ed. iib.,is extruded, it carries the coloring material as an integral part of the

fiber.This “locked-in” color is extremely fast to laundering (that is, it will not diminish); however, such colors can be sensitive to light and bleaching or may fade. The range of colors in which solution dyeing is done is rather limited for economic reasons.

The fiber manufacturer must produce substantial quantities of fiber to justify the expense of adding an extra step during the manufacturing process. Furthermore, fiber production takes place well in advance of the time when fabrics reach the market.

Fashion color trends may change fairly rapidly, so that, by the time a mass colored fabric reaches the market, the color may be out of fashion and not salable. For this reason, spun-dyed fabrics are generally produced in basic colors. Mass coloration is used on acetate to prevent gas fading. Gas fumes in the air may turn some blue or green dyes used for acetate to pink or brown.

Dyeing Fibers

When color is added at the fiber stage, this process is known as fiber dyeing or stock dyeing. It is a batch process in which loose (usually staple) fibers are immersed in a dyebath. dyeing takes place, and the fibers are dried. Exhaustion is quicker in fiber dyeing because the dye liquor has better access to fiber surfaces.

Levelness may be a problem but its effect can be minimized by blending fibers later during yarn processing. Stock-dyed fibers are most often used in tweed or heather effect materials in which delicate shadings of color are produced by combining fibers of varying colors. The yarns in Harris Tweed fabrics are a distinctive example of fiber dyeing. Fiber-dyed fabrics can be identified by untwisting the yarns to see whether the yarn is made up of a variety of different colored fibers. In solid-colored yarns untwisted stock-dyed fibers will be uniform in color, with no darker or lighter areas. Stock dyeing refers to dyeing a staple fiber before it is spun.

There are two methods.

The first method, bale dyeing, applied mostly on wool and all types of manmade fibers, is that of splitting the bale covering on all six sides, placing the entire bale in a specially designed machine (the covering and straps need not be removed), and then forcing the dye liquor through the bale of fiber. In stock dyeing, which is the most effective and expensive method of dyeing, the color is well penetrated into the fibers and does not crock readily.

**yarn & fabric dyeing **

Yarn Dyeing

When dyeing is done after the fiber has been spun into yarn, it is described as yarn dyeing. Cloth made of dyed yarns is called yarn-dyed. Yarn-dyed fabrics are usually deeper and richer in color. Yarn-dyed fabrics intended for laundering must be quite colorfast, or bleeding could occur. The primary reason for dyeing in the yarn form is to create interesting checks, stripes, and plaids with different-colored yarns in the weaving process.

If color has not been added either to the polymer or the fiber, it can be applied to the yarns before they are made into fabrics. Yarns may be dyed in skeins, in packages, or on beams. Special dyeing equipment is required for each of these batch processes. In skein dyeing, large skeins of yarn are loosely wound on sticks and placed in a vat for dyeing. In package dyeing, the yarn is wound onto a number of perforated tubes or springs. The dye is circulated through the tubes to ensure that the yarns have maximum contact with the dye. Beam dyeing is a variation of package dyeing, which uses a larger cylinder onto which a set of warp yarns is wound.

Many types of fabrics utilize yarn of differing colors to achieve a particular design. Stripes in which contrasting sections of color alternate in the length or crosswise direction, chambrays in which one color is used in one direction and another color is used in the other direction, complex dobby or jacquard weaves, and plaids may all require yarns to which color has already been added.

Yarn-dyed fabrics may be identified by unraveling several warp and several filling yarns from the pattern area to see whether they differ in color. Not only will each yarn be a different color, but the yarns will have no darker or lighter areas where they have crossed other yarns.

Usually yarns are dyed to one solid color, but in a variant of the technique called space dyeing, yarns may be dyed in such a way that color-and-white or multicolored effects are formed along the length of the yarn.

Skein (Hank) Dyeing:

Yarn may be prepared in skein, or hank, form and then dyed. The loose arrangement of the yarn allows for excellent dye penetration. The skeins are hung over a rung and immersed in a dye bath in a large container.

Piece Dyeing

Fabrics that are to be a solid color are usually piece dyed. In piece’ dyeing, the finished fabric is passed through a dye bath where the fibers in the fabric absorb the dye. A number of different methods are used for piece dyeing, each of which differs slightly in the way in which the fabric is handled. Fabrics may be dyed in either continuous or batch processes. In continuous dyeing, the cloth continually passes through the dyebath. This is the cheaper process and, where possible, is used for dyeing large yardages. Batch dyeing is used for shorter fabric lengths.

Some fabrics are dyed in open, Rat widths. Knitted fabrics and those woven materials that are not subject to creasing are handled in “rope” form, that is, bunched together and handled as a narrower strand. They are usually attached at the ends to form a continuous loop. Some dyeing methods are especially suitable for certain types of fabrics and unsuitable for others. Many different kinds of machines can be used for piece dyeing. The great bulk of dyed fabric on the market is dyed in the piece.

Small lots of fabrics of all fibers are dyed in batches. Piece dyeing is thoroughly satisfactory as regards levelness, penetration, and overall fastness, assuming that the proper dyes have been used. Fabric may be piece-dyed whether it is composed of only one kind of fiber or yarn or of blends of different fibers or combinations of different yarns. When the fabric is made of one kind of fiber or yarn, then dyeing is relatively uncomplicated because the one appropriate dye is used. However, when the fabric contains a blend of fibers or combination of different yarns, then special procedures are required which employ different dyes that are each specific for the particular fibers used. These procedures are called union dyeing and cross dyeing.

Union Dyeing:

This process of dyeing piece goods made of different fibers or yarns in one color may be readily accomplished. Although different fibers may require different dyes to obtain the same color, this may be done by putting the appropriate color dye that is specific to each type of fiber into one dye bath.

Cross Dyeing:

One method is a combination of stock dyeing or of yarn dyeing with subsequent piece dyeing. Cross dyeing produces varied effects. For instance, either the warp or the filling yarns may be stock-dyed or yarn-dyed, one set of yarns being left undyed. The fabric is piece-dyed after weaving; thus, color is given to the undyed yarn in a second dyebath, and the yarns that were originally stock-dyed or yarn-dyed acquire some additional coloring, which blends with the piece-dyed portion of the fabric. If yarns of vegetable fibers have been combined with yarns of animal fibers in a fabric that is to be piece-dyed, two separate dye baths must be used. The fabric is dipped into both solutions, each of which affects the fiber for which it has an affinity. This provides colorful effects. Still another method of cross-dyeing is to immerse a fabric composed of two different types of fibers into one dye bath containing two different dyes, one specific for each of the fibers. One of methods of piece dyeing is described below.

Beck Dyeing(Beam dyeing)

Long lengths of cloth that are to be dyed on a continuous process are very often beck-dyed, or box-dyed, by passing the fabric in tension-free rope form through the dyebath. The rope of cloth moves over a rail onto a reel, which immerses it into the dye and then draws the fabric up and forward to the front of the machine. The process is repeated as long as necessary to dye the material uniformly to the desired intensity of color.

Beam dyeing, which is used for lightweight, fairly open-weave fabrics, utilizes the same principle as beam dyeing of yarns. The fabric is wrapped around a perforated beam and immersed in the dyebath. Tightly woven fabrics would not allow sufficient dye penetration; hence, this method must be applied to loosely woven cloth. It has the added advantage of not putting tension or pressure on the goods as they are processed.

Jig Dyeing:

This method utilizes the basic procedure of beck dyeing. However, in jig dyeing, the fabric is held on rollers at full width rather than in rope form as it is passed through the dye bath. The rope of cloth moves over a rail onto a reel, which immerses it into the dye and then draws the fabric up and forward to the front of the machine. The process is repeated as long as necessary to dye the material uniformly to the desired intensity of color. Batch processes that dye fabric in flat widths are jig and beam dyeing. Jig dyeing is a process that places greater tension on the fabric than the beck and jet machines. Fabrics are stretched across two rollers that are placed above a stationary dyebath. The fabric is passed through the dyebath and wound on one roller. The motion is then reversed until the desired exhaustion or depth of shade is achieved. The tension created by placing the fabric on the rollers means that this process must be reserved for fabrics with a fairly close weave that will not lose their shape under tension.

Jig dyeing

Jet dyeing: - Jet dyeing is a newer method that uses propulsion of the dye liquor through the fabric to improve dye penetration. Dyeing takes place in a closed system that carries a fast-moving stream of pressurized dye liquor. A fluid jet of dye penetrates and dyes the fabric. After it passes through this jet, the fabric is floated through an enclosed tube in which the fluid moves faster than the fabric. This prevents the fabric from touching the walls, keeping it constantly immersed in the dyebath. Turbulence is created by locating elbows in the tube. The turbulence aids in diffusing dyes and dyebath auxiliaries. Since no pressure is put on the fabric, even delicate fabrics can be dyed by this process. Jet dyeing has the advantage of being economical in operation and at the same time allowing a high degree of quality control

1. Fabric guide roll

2. Loading & unloading port

3. Header tank

4. U tube

5. Suction control

6. Suction control

7. Suction control

8. Delivery control

9. Main control

10. Filter

11. Heat exchanger

12. Service tank

Solution Pigmenting, or Dope Dyeing

During the production of manmade fibers, a great deal of time and money can be saved if the dye is added to the solution before it is extruded through the spinnerets into filaments. This method also gives a greater degree of colorfastness. A process called solution pigmenting, or dope dyeing, has been used for manmade fibers ranging from rayon through saran and glass fiber.

Garment Dyeing

Certain kinds of non-tailored apparel, such as hosiery, pantyhose, and sweaters can be dyed as completed garments because they are each made of a single component and will not be readily distorted. However, allowance must be made for anticipated shrinkage. A number of garments are loosely packed into a large nylon net bag. The bags are then put into a paddle dyer, which is a tub with a motor-driven paddle that agitates the dye bath. Except for dyeing socks and narrow fabrics, garment dyeing, is the process of dyeing completed garments, remained a rather unimportant novelty until the second half of the 1980s; Industry sources credit two factors with a sharp increase in the amount of garment-dyed apparel. First, fashion demanded small lots of garments from fabrics with stonewashed, ice-washed, tie-dyed, overdyed, and distressed effects. These effects were more readily achieved through garment dyeing than traditional dyeing methods. The second factor was the ability of manufacturers to achieve Quick Response or Just-In-Time production through garment dyeing.

The lead time required for delivery of orders in the traditional dyeing system is about eight weeks. For garment-dyed products lead time is about two weeks. Although the process of garment dyeing is more costly than traditional piece dyeing (estimated at $1 to $3 per item), savings are achieved in the long run because manufacturers and retailers need not maintain large inventories. If undyed merchandise is left from one season, it can be dyed for sale the following season. However, if it has already been dyed and a different color is wanted, it must be overdyed, given a second dyeing to a different color. Manufacturers can be more responsive to fashion trends by producing small dye lots.

Garment dyeing is primarily applied to cotton fabrics; however, high-pressure equipment can be used to process polyester and cotton blends. To achieve consistently good results with garment dyeing, manufacturers must exercise care in a number of areas.

1. Fabric. All fabric used in one garment must come from the same bolt of fabric. If, for example, one trouser leg of a pair of jeans is cut from one bolt of fabric, and the other from another bolt, each leg may dye to a different shade. The result would be jeans in which the legs do not match.

2. Shrinkage. Fabric must also be tested for shrinkage before cutting of garments, and garments must be cut large enough to allow for shrinkage so that sizes will be accurate.

3. Thread. Thread must be chosen carefully and tested to be sure it will accept the dye in the same way as the fabric. One hundred percent cotton thread is preferred, but even with allcotton thread there may be problems. For example, mercerized thread will dye to a darker shade than unmercerized garment fabric. This will make the stitching stand out from the background fabric.

4. Labels, button, zippers. All of these supplies must be compatible with the garment fabric in terms of reaction to the dye and shrinkage. The machines used for garment dyeing are called paddle machines. To avoid entanglement during dyeing, garments are generally placed inside bags. Paddles in the machine rotate, changing directions periodically, to make sure that all pieces being dyed are equally exposed to the dye liquor. Garments are generally washed before dyeing, to remove any finishing materials that would interfere with dyeing, and after dyeing to remove excess dye.

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Process sequence of cutting section in apparel garments industry

Process sequence of cutting section in apparel garments industry

Store ↓ Fabric Fault Checking ↓ Relaxation ↓ Shade Checking ↓ Prepare the fabric in the fabric spreading m/c ↓ Spreading ↓ Marker attachment ↓ Cutting ↓ Numbering ↓ Bundling ↓ Panel Check (QC) ↓
Fault	←     ↔    →				OK
↓			↓ ↓ ↓
Replace Cut
↓
→     →      ←    ← ↓
Solid		←     ↔    →		Not Solid
↓ ↓ ↓			↓
			Print / Embroidery
			↓
→     →      ←    ← ↓
Checking & Counting (QC)
↓
Sewing

Store of Garments:

Garments store is the sector where all the raw material are stored which are need to make a garments. Raw fabric for cutting, which will be processed to garments by cutting, sewing, is kept here until the process starts. This fabric comes from the main factory after knitting and dyeing. Different types of fabrics like Single Jersey, Lycra, fleece, rib etc. There are three sections, Fabric Store, Garments Store, and General Store. In Fabric store all the fabric is being stored. In Garment store, all the items without fabrics that are needed to produce garment is stored. Finally, in General store, all the related things that is needed to run a factory is stored.

In fabric store, normally 250-300 ton fabric comes to store in each day. Now, around 37 ton fabrics are stored. Few days ago, this number was around 100 ton. Cutting department get fabrics from here. There is a Fabrics Requisition sheet where all the information is being written about the fabrics movement from store to cutting section.

Fabric Fault Check out before cutting:

This quality control section is very important before garments cutting. The fabric is roughly checked from dyeing section and then those are sending to garments factory for producing complete garments. Usually very small amount of fault comes from dyeing. Small hole and pin hole are the main fault get in cutting quality check. But a single pin hole in single part of garment could be the cause of rejection of garments and it is a major defect. That’s why a thoroughly checking is done before cutting. Here Fabrics are being checked before going to relaxation section of cutting. Required number of table is preserved for fault checking. Fabric fault like hole, yarn miss, dart etc are being checked. Normally 10% fabric is checked. There are two popular fabric fault checking system is exist. Ten point system and four point system. Usually four point system is very much popular for knitted fabric and ten point system is popular for woven fabric.

Relaxation of fabric for cutting

Normally Fabric came in a roll form. Before sending the fabric for cutting, it is necessary to relax the fabric. Usually fabric comes as the form of role or gathered from textile dyeing section. So the dimensional stability of fabric is relatively lower and it contain crease mark. The fabric is kept in an open place for around 12-24 hours according to fabrics type and buyer requirements. Relaxation time for lycra fabric and pique fabric is around 3 days and minimum 24 hours. For Single Jersey and Fleece fabric, standard relaxation time is 24 hours and minimum time is 12 hours. There are racks to store the fabrics for relaxation.

Shade Checking before cutting:

Shade checking is most important part in cutting section. Before spreading the fabric on the cutting table, relaxed fabric is rechecked for shade variation in time of relaxation. If the fabric is ok then it goes for cutting. If not, then that part of fabric is rejected and transferred for further reprocessing. 

Prepare the fabric in the fabric spreading m/c

The fabric is being gathered in the machine in a small lay form that will be easy to spread the fabric in the fabric cutting table. At least two men are needed to do the job.

Spreading of fabric:

Fabric is spread on the table by spreader machine. One man control the machine and around 6-10 people to adjust the fabric to its specific dimension. Number of layer varies according to the marker length and production needed. More the layer length will be, the more will be the production rate.

Marker attachment

After laying down the specific number of fabric on the cutting table the marker paper is over laid on the fabric. Then the marker paper is attached to the fabric  by some adhesive. 

Cutting

There are cutting man to cut the laid fabrics according to the marker sketch. Normally two men do this job. Generally 10-15 number of laid fabric is being cut.

Numbering

The fabric peaces are being numbered by a labeling machine to identify these peaces in future.

Bundling

All the numbered fabric is then bundled together and send it for checking.

Panel Check (QC)

Here, the fabric is being checked for any fault. There is a sticker with all the information that is needed to identify this bundle in future for further processing like, Date, Buyer, cutting no., size, bundle no, quantity, serial no., color, lot no. In checking normally Cutting no., size, serial no. are checked.

After Panel Check

If there is a fault in the fabric then it send for further processing. If there is some spot in the fabric then it will be washed and if there is hole or some thing that needed to be replaced then is send for replace cutting.

If the garment will be solid then it goes for sewing. But if some fabric peaces needed to be printed or embroidery then it goes for it. After returning from printing or embroidery the fabric is ready for sewing.  

Checking & Counting (QC)

After doing, the entire job in cutting section the fabric is checked and counted. Then, all these peaces go for sewing. Responsible people from sewing department receive the fabric from cutting department.

Sewing

Now, the peaces of fabrics are joined together to make the final product.

Modern textile testing and quality control equipment

Modern textile testing and quality control equipment:

Quality: Quality is the attribute of the products that determines its fitness for use, or according to Japanese Standard (JIS), textile (fibre, polymer, yarn, fabric) quality is all specific properties and performance of a textile product or service that can be evaluated to determine whether a product or services satisfactorily meets the purposes of its uses. The level of quality is measured by “ inherent properties and performances which is the subjects of evaluation or the characteristic related to its phsico-mechanical or chemical properties, dimension, longevity, durability utilization or any other requirement used to define the of the product or service is known as “quality characteristics”.

Standard: It is an agreed document established mainly with respect to technical matters related directly or indirectly to an article or service. So that profit or convenience may be obtained with fairness among the person concerned.

Testing:  The way to control or the way to check or verify the nature & characteristics. Or, the way to checking or verifying.

Modern Fibre or Polymer Quality Testing Equipment:

Fibre characteristics must be classified according to a certain sequence of importance with respect to the end product and the spinning process. Moreover, such quantified characteristics must also be assessed with reference to the following

• What is the ideal value?

• What amount of variation is acceptable in the bale material?

• What amount of variation is acceptable in the final blend?

Textile fibre contains some basic characteristics. 

Following are the basic characteristics of cotton fibre

• Fiber length

• Fineness

• Strength

• Maturity

• Rigidity

• Fiber friction

• Structural features

Name Of The Machine for fibre testing and quality control	Function of the Fibre/ Polymer Quality testing machine
1.HVI (High Volume Instrument)	It’s a very popular fibre characterization and quality testing machine in USA, UK, China, Korea and other countries. It is very cause sensitive and provides perfect fibre quality testing result. 50% span length, 2.5% span length, Uniformity ratio, Mic value, Color grade, Maturity ratio, gm/tex (tenacity), SFI (Short Fibre Index) etc. Suitable for knitted yarn production.
2.AFIS (Advance Fibre Information System)	It is also popular fibre testing machine and very cause sensitive and provides perfect fibre quality testing result. 50% span length, 2.5% span length, Upper half length, Trash%, Neps, Seed coat neps both in number & weight, short fibre content, Maturity ratio, fibre strength etc. Suitable for export woven fabric production.
3.Digital Fibre Graph	It is also popular fibre quality testing equipment and used to measure 50% span length, 2.5% span length, Uniformity ratio.
4.Digital Moisture meter	It is also popular fibre quality testing equipment and used to measure Directly Moisture content % is determined.
5.Trash Selection	It is also popular fibre quality testing equipment and used to measure Trash% in raw cotton is found out.
6.Sling Hygrometer	It is also popular fibre quality testing equipment and used to measure Directly RH% is measured.
7.Precision Polarizing Microscope	Ihis type of testing machine is used for Fibre identified with digital photographs, maturity ratio.
8.Stetometer with Torsion Balance	Bundle fibre strength is measured by this testing machine.
9.Instron	This type of testing machine is rear in used. Single fibre strength is measured (research based) by this testing equipment.

Modern Yarn Quality Testing Equipment:

Yarn is a main element for textile production. Good yarn contains some characteristics. The main characteristics are strength, elongation, hairiness, uniformity, diameter etc.

Name Of The Machine for yarn testing and quality control	Function of the Yarn Quality testing machine
1.Uster Evenness Tester 4&5	This yarn quality testing equipment is used to measure U%, CV%, Imperfection (Thick place /1000m, Thin place/1000m, Neps /1000m), Irregularity index, Relative count, hairiness etc. In case of UT-5 polypropylene content in yarn is also determined recently.
2.Uster Tenso Jet	This yarn quality testing equipment is used to measure  Single yarn strength & Elongation% is determined.
3.Uster Tenso Kind	This yarn quality testing equipment is used to measure Lea strength, Breaking force, Elongation% determined.
4.Uster Tenso Rapid	This yarn quality testing equipment is used to measure Single yarn strength, Lea strength & Fabric strength, Elongation% is determined.
5.Uster Classimat	This yarn quality testing equipment is used to measure Yarn fault in category wise determined (23-27 categories).
6.Auto Cone Winder	This yarn quality testing equipment is used to measure Auto splicing, Slubs removes in running m/c.
7.Uster Auto Sorter	This yarn quality testing equipment is used to measure Rapidly Yarn count, Sliver/Roving hank etc

Modern Fabric Quality Testing Equipment:

Textile fabrics are made for various purpose, each of which has different performance needs. The chemical and physical states of textile fabric identify what will the end use of this, and ultimately whether it is reasonable for a specific use. Fabric testing makes a crucial role in gauging product quality, ensuring regulatory compliance and assessing the perfection of textile materials. It provides information about the physical or structural, chemical and performance properties of the textile. As user become more aware and more demanding of products, the number of tests required for textile fabrics has grown. As a result the testing of fabrics is increasingly varied, in constant flux and full of the unprecedented challenges of globalization. With the onset of modern types of fabrics for the garments factory and of technical textiles for functional applications, and with the growing number of invention taking place in the apparel sector, fabric testing processes have undergone tremendous changes and there is required to realize all the procedures before a testing method is involved to investigate the performance of fabrics. 

Name Of The Machine for fabric testing and quality control	Function of the Fabric Quality testing machine
1.Automatic Pick Counter	Ends/inch & Picks/inch is digitally measured.
2.Universal Titan	Fabric strength, Elongation with printed form.
3.Spectro Photometer/Data    Color	Pass/fail (quality if fabric), Recipe formulation, Grey scale value, Whiteness value, Shade% etc is determined.
4.Wascator	Shrinkage% is determined by programming.
5.Martindile Abrasion &    Pilling tester	Abrasion resistance as well as pill formation on the fabric is determined.
6.Seam Slippage Tester	Seam strength & Elongation % is determined.
7.GSM Cutter with Balance	GSM of the fabric is measured.
8.Color dispenser	Automatically stock solution is prepared according to Programming.
9.Megasol	Light fastness of the dyed fabric is determined digitally.

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