Most common Textile Inspection System

Piece goods inspection system:

In 1955 ten points piece goods evaluation was approved by the textile distribution & national federation of textiles. This system assigns penalty points to each defect.

Ten points system:- Filling defects penalty
Warp defects                 Penalty                       Full width                    10 points

10-30 ̎                          10 points                   5 ̎ ½ the width:                    5 ″

5-10 ̎                                 5 ″                                1-5 ̎ :-                        3 ″

1-5 ̎                                   3 ″                           up to 1 ̎ :-                        1 ″

Up to 1 ̎ 1 ″

Under the ten point system, a piece is graded a fixed if the total penalty point do not exceed the total yardage of the piece. A piece is graded a ‘second” if the total penalty points exceed the total yardage of the piece.

Four points system:

It is widely used in textiles. It is simple & easy to under stand. Inspection is done about 10% of the product in the shipment. This system has been applied by AAMA (American Apparel manufacturing association).

The four points system classifies classified defects as follow:

Size of defects                                             Penalty

3 ̎ or less                                                     1 point

Over 3 ̎not over 6 ̎                                       2 ″

Over 6 ̎but not over 9 ̎                                 3 ″

Over 9 ̎                                                       4 ″

A maximum 4 points is changed for one leniaroooo yard

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Fabric faults produced during weaving & knitting production

Weaving fault:
Warp way defect:
I. Warp stitching : Occurred due to want of interlacement between warp & weft yarn which happen:
   Ø If the warp threads of one shed goes to another.
   Ø Faulty dobby or jacquard mechanism.
   Ø Warp yarn if loose.
   Ø Height of the harness card if not equal.
   Ø Warp is not properly sized.

a) Long float: causes due to
   Ø If the warp yarn does not take part in interlacement.
   Ø Tappet is not properly tied.
   Ø Peg if dobby displaced.
   Ø Jacquard harness or cord cutting if defective.
   Ø Worn out Reed if used.

b) Wrong warp threads: due to drafting & lifting.
Missing warp: causes due to:
   Ø Wrong denting.
   Ø Broken warp yarn in the beam.
   Ø Out of order warp stop motion.

d) Double warp: warp way marks on the fabric due to:
   Ø Wrong reed count used.
   Ø Wrong denting in the reed.

e) Loose warp: Causes due to
   Ø Loose warp exist on the beam in loop form.
   Ø Yarn tension in the dropper.
   Ø Size picks up unequal.

f) Knot in the warp yarn: If there are any knots in warp yarns.

g) Selvedge effect: Causes due to :
   Ø If the body and selvedge warp yarns tension is unequal.
   Ø If the reed space is greater but the width of the fabric is les.
   Ø Sharp temple ring spikes.

h) Weft cut at the selvedge: due to
   Ø Absent of weft yarn in the selvedge
   Ø Defective ring temple.
   Ø If the temple not properly set.

i) Temple mark: Mark on the selvedge of the fabric due to: light fabric if course temple is used.

Weft way fault:
1. Miss pick or broken pick:- Causes Due to
   Ø Broken pick.
   Ø Yarn of pirnoooo is finish.
   Ø If weft yarn breaks at the middle.
   Ø Picking much uniform occurred by empty shuttle.

2. Broken design: If the lifting mechanism is defective.

3. Thick & thin place which is called bar on the fabric.

4. Shuttle mark:
   Ø Shuttle flies.
   Ø Shuttle box is not properly set.

Defective of knitted goods to be unspected:

1. Broken ends: If the yarn breaks, holes create in the fabric.
   Ø During loop formation if the yarn previously broken in the needle.

2. Drop stitch:
   Ø Due to defective needle.
   Ø Yarn feeder not properly set.
   Ø Wrong take up mechanism.
   Ø Stitching tension if not proper.

3. Slugging.
   Ø Only occurs in continuous filament yarn.
   Ø Occurs due to mechanical strain in the next process stages.

4. Tuck & doable stitch: Occurs due to badly oooo or knitted loop. It results the formation small brads or thick & thin places in large ascoooo.

5. Bunching up: Visible knots in the fabric eyes known as beads.

6. Vertical stripe: Vertically shown streaks on the Wales which causes due to:
   Ø Gauge is not done according to count.
   Ø Stitch size.
   Ø Course density.

7. Horizontal stripe: unevenness along the course direction.
   Ø Yarn feeder if not properly set.
   Ø Tension if not uniform.

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AQL | Acceptable Quality Limits or Level

Major concept of Acceptable Quality Limit or Level:
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It is the allowable percent defective in a lot. This is introduced according to American military Standard of product inspection rules. There are generally 6 AQL used in textile which are as follows:- 1%,1.5%,2.5%,4%,6.5%,and 10%. Among them 2.5%,4%,6.5% and 10% are widely used and accepted according to price and type of garments.

Uses of AQL: In this system, sample is selected statistical method by using random sampling technique from a lot. After proper inspection along with the test results, the decision is taken, whether the lot will be accepted or rejected. Now a days this system is widely used in garments sector before the delivery. Although it is used from raw material to finished product also.

Acceptable sampling system consists of five parts:
1. Lot size
2. Sample size
3. AQL
4. Acceptable number
5. Reject number

Quality Inspection of factories:
According to JIS, Inspection is defined as “ to measure goods by some methods and by comparison with the results obtained against the criteria to judge whether the individual goods are defective or not

In textile factories the fabrics are inspected at the grey state, after pretreatment, coloration and finishing. After inspection the fabrics are classified according to their quality. Therefore fabrics are inspected to meet the requirements of the customers.

The fabrics are categorized in the following way depending upon the faults:

I. Fresh or First quality: Fabrics, hemming major, minor faults according to buyer specification and requirements.
II. Short length or two parts: It is a piece of cloth having a shorter length( More then 50 cm ). Jar parts become equal to fresh quality. Generally buyers gives (3-5)% discount value for the short length.
III. Seconds: Fabrics containing much objectionable minor defects and (8-15)% discount is allowed.
IV. Fents: Cut pieces of fabric measuring 90 cm or more but less than 150 cm lengths. For fents trade discount is (15-30) %.
V. Rags: Cut pieces of fabric measuring 25 c or more but less than 90 cm. This categories are sold by weight and realization is only about 50% of fresh fabric.
VI. Chilly: These are pieces of 25 cm length fabric less than this. These fabrics are bought & sold and trade discount generally given is ( 50-80).

Quality Parameters of Woven Fabrics to be inspected are as follows:

(1) Dimensional characteristics:
a) Length b) Width c) Thickness

(2) Weight of fabric:
a) Weight/unit area b) Weight/unit length

(3) Fabric strength & Elongation
a) Tensile strength b) Tearing c) Bursting

(4) Threads/inch:
a) Ends/inch
b) Picks/inch

(5) Yarn count
a) Warp count
b) Weft count

(6) Crimp
a) Warp count
b) Weft count

(7) Handle

a) Stiffness
b) Drape

(8) Crease resistance & crease recovery

(9) Air permeability

(10) Abrasion resistance and pilling.

(11) Shrinkages/Dimensional stability

(12) Different fastness properties:-
a) Washing fastness
b) Light fastness
c) Perspiration fastness
d) Rubbing

(13) Flameability

(14) Water resistance or absorption power

(15) Design of fabric

(16) Appearance of fabric

Quality parameters for knitted fabric to be inspected:

1. Strength & elongation
2. Course density
3. Wales density
4. Loop length
5. Deformation
6. GSM
7. Yarn count
8. Design

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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.

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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.

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SEWING THREAD

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Sewing threads have to make with the properties by which it can be possible to sewn garments smoothly. It has to be designed for smooth & efficient stitching. It should contain the properties for these it will not break in the time of sewing & after complete the sewing as well as up to buyer use. The composition & the construction have to manufacture as required for the efficient smooth stitching to the proper selection of fabric, based on the seam type.

CONSTRUCTION OF THREAD

Sewing threads are made of cotton, linen, silk, rayon, or polyester or blends thereof. The properties of the fiber determine its use and application. For example, cotton is the most widely used because of its high versatility and low cost; rayon, which is much weaker, is used primarily for fancy stitch work; polyester is used where strength and water repellency are more important. 

All sewing threads are made of ply yarns. The single yarns, which may be spun, filament, or multi-component are highly twisted (plied) to form a firmer and more uniform thread than ordinary yarn. Sewing thread may be given special finishes, such as mercerizing, glace or water repellency or swelling to serve particular uses. 

THREAD SIZES

The size of spun thread had been expressed in terms of its diameter: the higher the number the finer the thread. At one time, thread had been made only from three-ply spun yarns. Therefore, a spun yarn thread of 50 three ply (50/3) had a ticket number of 50, a thread of 60 three ply (60/3) had a ticket number of 60, and so forth.. Subsequently, the number of plies in sewing thread was extended to, two, three, four and six ply. A ticket number of 50 could therefore indicate a 50 two ply (50/2), a 50 three ply (50/3), a 50 four ply (50/4), or a 50 six ply (50/6); but the thickness of the thread in each case was the same, while each ply was thinner. The greater number of ply yarns implied greater thread strength. The size of mercerized cotton sewing thread were identified by letter as well as number. The range was found from F (coarsest) to A (medium) and then from 0 to 00000 (finest). 

Identification of thread size, called ticket number, is undergoing a transition. Different kinds of yarns had different numbering designations. The Thread Institute adopted a standardized ticket numbering system based on the tex system of numbering yarn. 

The tex system is intended to give an orderliness by providing one ticket numbering system based upon metric system which is now universally accepted. Since tex is the weight in grams of a 1000-meter length and is a direct numbering system, the greater the weight the thicker the thread and therefore higher the number. Ticket numbers are based on actual tex size of the thread in the griege state, i.e. twisted, braided, or extruded before any dyeing, special processing, or finishing. The purpose of the stipulation is intended to obviate the alteration of the thread’s apparent size by any finish. 

STANDARD SEWING THREAD TEX TICKET NUMBER

1          10            35           105           300
2           12           40           120           350
3           14            45           135            380
4           16           50           150           400
5           18           60           180           450
6           21            70           210           500
7           24           80           240           Above 500, in
8           27            90           270          increment of 100
9           30

One important caution should be noted when using the tex ticket numbers. When selecting proper thread size, threads of the same fiber and type must be compared. Since the tex ticket numbering system is based on weight and since different kinds of fibers and/or types have different weights and moisture, the same tex number of threads of different fibers or types will not necessarily be of the same thickness and may therefore not be interchangeable. 

THREAD SELECTION

Selection of the appropriate kind and size of sewing thread is important. The thread should be as fine as possible, consistent with the nature of the fabric and the strength requirements of the stitching. Finer threads could be less obvious, they become hidden below the surface of the cloth, and they are less subject to abrasion than heavier threads. Also, finer threads require finer needles which cause less fabric distortion than heavier needles. Threads composed of the same kind of fibre as that of the fabric is also important because of such factors as general appearance, color fastness, finish retention, elasticity and strength. 

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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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Production of filament yarn with man-made fibre by Emulsion spinning and Wet spinning

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In melt spinning the fiber polymer is melted and the molten solution is forced through the spinneret. As the soft filaments emerge from the spinneret into the cooler environment, they harden into a standard filament form. Melt spinning requires no chemical change & any kind in the polymeric material from which the fiber is formed. It does require that the fiber polymer can be melted without altering the chemical state of the material. Fibers formed by this process are Nylon, Polyester, and glass. 

Emulsion Spinning 

Emulsion spinning is not used to a great extent but it is important for selected types of specialty fibers. Some raw polymeric materials cannot be processed by wet/dry/melt methods, because they either breaks drown when heated to a melting temperature or are not soluble in solution that can be used. For these substances the emulsion process is necessary. 

The polymer dispersed or emulsified into a solution, the dispersion or emulsion is then forced through a spinneret, and as the emulsion leaves the spinneret, the polymer form into a fibrous shape. Depending on the type & fiber, the fibrous form produced by this method may be staple / filament length. Teflon is an example of a fiber spun by the emulsion process. First, polymers, whether natural or synthetic, must be converted into liquid form to be spun. This is done either by dissolving the polymer in a suitable solvent or by melting it. This polymer solution or polymer melt is sometimes referred to as the spinning dope. Cellulose, the raw material for most naturally derived manufactured fibers, is not easily dissolved. Accordingly, the cellulose polymer is usually modified before it is dissolved. Synthetic polymers are put together in the plant before the dissolution or melting step. 

Before actually forming the fiber, certain characteristics can be added to the polymer material. Many manufactured fibers are naturally bright, with a high luster. If dull or semi-dull fibers are wanted, delustering agents can be added to the molten polymer to break up light rays and decrease shine. Colored pigments, flame retardants, and compounds to absorb ultraviolet light can also be added. Occasionally substances are added during polymer synthesis so that they are incorporated into the polymer molecules themselves. 

Wet Spinning 

Wet-spun polymers are, like dry-spun polymers, converted into liquid form by dissolving them in a suitable solvent. The polymer solution is extruded through a jet into a liquid bath. The bath causes coagulation and precipitation of the fiber. Solvents are usually recovered from the liquid bath and are recycled. Viscose rayon and some acrylics are wet spun. 

It is possible to add special chemical reagents to the liquid bath that produce selected changes in the fiber. This is done in the manufacture of some high-strength rayons, for example; into a liquid bath. The bath causes coagulation and precipitation of the fiber. Solvents are usually recovered from the liquid bath and are recycled. Viscose rayon and some acrylics are wet spun. The polymer or substance to be used is making the fiber is dissolved into some type & solution, then is forced through the spinning jet into another liquid, which react with fiber solution the process involves one & the following reaction: 

(a) The fiber polymer may have been chemically changed in order to make it soluble in the solvent used when this occurs the fiber solution reacts with the receiving solution & reverses the chemical reaction so that the material is reformed into a fiber shape. The difference is that in reforming, a filament fiber shape has been made rather than a polymer in some other form, such as fibrous mass, chip or pellet. This process refers to the fiber solution as a derivation & the fiber form, the solution into which this passes is the coagulating bath & the actual process is typically called regeneration. 

(b) Wet-spinning may also be used when the fiber solution does not change the chemical form of the fiber. The solution is forced into a coagulating bath, which reduce the concentration of the fiber solution sufficiently to reform the fiber, this time in a filament form Fibers formed by wet spinning are rayon, acrylicA variant of wet spinning, called dry-jet wet spinning, has been developed to produce some of the newer fibers such as the aramid. Instead of the spinneret being immersed in the spinning bath, it is placed slightly above the bath so that there is a small air gap, usually less than an inch. The fibers exiting the spinneret can be stretched to orient the molecules before they enter the bath to be solidified. 

This process develops high orientation and crystallinity in one step, rather than drawing in a separate step Although melt-, dry-, and wet-spinning techniques are used to form the vast major-ity of manufactured fibers, several other spinning techniques also exist and may be applied in a limited number of specialized situations. High-molecular-weight poly-mers, such as those in Spectra@ polyethylene, are formed by solution spinning or gel spinning. As in wet and dry spinning, the polymer is dissolved in a solvent. The polymer and solvent together form a viscous gel that can be processed on conventional melt-spinning equipment to form a gel-like fiber strand. Later in the processing, the solvent is extracted and the fibers stretched. Fibers made from polymers that have extremely high melting points and are in-soluble present obvious difficulties in spinning. Such materials may be spun by a complex process called emulsion spinning in which small, fibrous polymers are formed into an emulsion, aligned by passing the emulsion through a capillary, then fused or sintered (combined by treating with heat without melting), passed through the spin-neret into a coagulating bath, and subsequently stretched

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Production of filament yarn with man-made fibre by Melt spinning and dry spinning

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Man Made Fiber Formation 

Man-made fibers are polymeric forms that are produced by some type of chemical which or by the regeneration & natural polymers in a new physical form. The polymer is connected into some type & liquid / fluid state and forced through a spinnerette. Although most spinnerette are made with round openings, some may use orifices & other shape is order to produce fiber with special characteristics. 

The basic steps in producing manufactured fibers are as; 

The liquid polymer is then extruded through a spinneret. Each spinneret has a number of holes, and each hole produces one filament. As they exit the spinneret the filament fibers are solidified by cooling of melted polymers, by evaporating the solvent, or by precipitating the polymer from solution. These methods of solidification are the bases of the three primary fiber manufacturing processes. Other spinning methods that have been developed are described later in this chapter. 

Filament yarns are described by denier (that is, size) and number of filaments; for example, filaments described as 70/34 represent 70 denier/34 filaments. When fibers being extruded are intended for conversion into staple lengths, spinnerets with larger numbers of holes are used to produce more filaments that are later cut into staple lengths. Spinneret holes are spaced to allow the filaments to be extruded without touching each other. The holes must be exactly the same size to produce uniform fibers. The metal used in the plate must be capable of withstanding high pressures or corrosive spinning solutions. 

Most fiber spinning processes include a final step of drawing in which the filaments are stretched around rollers. 

Melt Spinning 

Melt spinning take advantage of the thermoplastic characteristics of polymers. Chips of solid polymer about the size of rice grains are dropped from a hopper into a melter where heat converts the solid polymer into a viscous liquid. The liquid forms a “melt pool” that is pumped through filters to remove any impurities that, would clog the spinneret and is delivered to the spinneret at a carefully controlled rate of Row. Melt spinning is simpler and cheaper than other spinning methods; therefore, it is used except when polymers cannot be melt spun. 

The spinneret holes are usually round, but noncircular holes are also used to make filaments of various cross-sectional shapes. Melt-spun fibers may be made through Y-shaped holes that yield a three-lobed fiber or C-shaped holes to produce a hollow filament, for example; The diameter of the fiber is determined by the rate’ at which the polymer is supplied to the hole in the spinneret and the windup speed, not by the diameter of the hole. When the molten polymer emerges from the spinneret hole, a cool air current is passed over the fiber, causing it to harden. Failure to maintain constant feeding speed of molten polymer or changes in the temperature of cooling will cause irregularities in the diameter of the fiber. Nylon and polyester are the most common melt-spun fibers. One of the latest developments in melt spinning has been the significant increase in spinning speeds. Processing speed has increased from less than 1,000 meters per minute in the 1960s to over 7,000 meters per minute today. This is the equivalent of a car traveling over 250 miles per hour. Higher-speed spinning is cost-effective and up to a certain point increases the orientation of the polymers in the fibers. Beyond a speed of about 6500 meters per minute, however, this advantage disappears as there is not enough time for the polymers to crystallize and the fibers may break. 

Dry Spinning 

In dry spinning the fiber solution is forced through the spinneret into a warm air chamber. The warm air causes the solvent used to make the fiber solution evaporate & the filament fibers are formed & hardened. This process, too may involve converting the fiber polymer into a different chemical form that is soluble in a suitable liquid As the solvent evaporate, the fiber polymer is reconstituted & return to its original chemical form, but now it is in a filament shape. 

Many polymers are adversely affected by heat at or close to their melting temperatures. Polymers that cannot be melt spun undergo other methods of spinning, such as dry spinning, to produce filaments. Dry spinning requires the dissolving of the polymer in a solvent to convert it into liquid form. Substances used as solvents are chosen not only because they will dissolve the polymer but also because they are safe and can be reclaimed and reused. 

The polymer and solvent are extruded through a spinneret into a circulating current of hot gas that evaporates the solvent from the polymer and causes the filament to harden. The solvent is removed and recycled to be used again. Dry-spun filaments generally have an irregular cross section. Because the solvent evaporates first from the outside of the fiber, a hard surface skin of solid polymer forms. As the solvent evaporates from the inner part of the fiber, this skin “collapses” or folds to produce an irregular shape. If the rate of evaporation is slowed, the cross section of the filament will be more nearly round. Acetate fibers and some acrylic fibers are dry spun. 

 

Fibers formed are: acetate, triacetate, acrylic, modacrylic, aramid fibers. 

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HOLLOW FIBERS | BI-COMPONENT FIBERS

HOLLOW FIBERS 

Hollow fibers are made of a sheath of fiber material and one or more hollow spaces at the center. These hollows may be formed in a number of different ways. The fiber may be made with a core of one material and a sheath of another, and then the central material is dissolved out. Alternatively, an inert gas may be added to the solution from which the fiber is formed, with the gas bubbles creating a hollow area in the fiber. Other experimental or proprietary techniques have been used to make hollow fibers. One involves spinneret holes with solid cores around which the polymer flows. 

Hollow fibers provide greater bulk with less weight. They are therefore, often used to make insulated clothing. For absorbent fibers such as rayon, hollow fibers provide increased absorbency. Some have been put to such specialized uses as filters or as carriers for carbon particles in safety clothing for persons who come into contact with toxic fumes. The carbon serves to absorb the fumes Bi-component Fibers 

As the technology for producing manufactured fibers has become more highly developed, manufacturers have turned to increasingly sophisticated techniques for creating new fibers. Not only are new generic fibers being created but also different polymers or variants of the same polymer can be combined into a single fiber to take advantage of the special characteristics of each polymer. Such fibers are known as bi-component fibers. 

The American Society for Testing and Materials (ASTM) defines a bi-component fiber as “a fiber consisting of two polymers which are chemically different, physically different, or both. Bicomponent fibers can be made from two variants of the same generic fiber (for example, two types of nylon, two types of acrylic) or from two generically different fibers (for example, nylon and polyester or nylon and spandex). The latter are called bi-component bi-generic fibers. 

Components in bi-component fibers may be arranged either side by side or as a sheath core. In making a side-by-side bicomponent fiber, the process requires that the different polymers be fed to the spinneret together so that they exit from the spinneret opening, side by side. Sheath-core bi-component fibers require that one component be completely surrounded by the other, so that the polymer is generally fed into the spinneret as shown in Figure. Variation in the shape of the orifice that contains the inner core can produce fibers with different behavioral characteristics. 

BI-COMPONENT FIBERS 

As the technology for producing manufactured fibers has become more highly developed, manufacturers have turned to increasingly sophisticated techniques for creating new fibers. Not only are new generic fibers being created but also different polymers or variants of the same polymer can be combined into a single fiber to take advantage of the special characteristics of each polymer. Such fibers are known as bi-component fibers. The American Society for Testing and Materials (ASTM) defines a bi-component fiber as “a fiber consisting of two polymers which are chemically different, physically different, or both. Bi-component fibers can be made from two variants of the same generic fiber (for example, two types of nylon, two types of acrylic) or from two generically different fibers (for example, nylon and polyester or nylon and spandex). The latter are called bi-component bi-generic fibers. 

Bi-component fibre

Components in bi-component fibers may be arranged either side by side or as a sheath core. In making a side-by-side bi-component fiber, the process requires that the different polymers be fed to the spinneret together so that they exit from the spinneret opening, side by side. Sheath-core bi-component fibers require that one component be completely surrounded by the other, so that the polymer is generally fed into the spinneret as shown in Figure. Variation in the shape of the orifice that contains the inner core can produce fibers with different behavioral characteristics.

POLYMER SPINNING | DRAWING OR STRETCHING AND HEAT SETTING OF POLYMER YARNS

POLYMER SPINNING 

Polymer spinning is important part of man made fiber and yarn manufacturing technology. Polymer spinning is very popular and result oriented synthetic spinning method. Although melt- spinning, dry-spinning, and wet-spinning techniques are used to form the vast majority of manufactured polymer fibers, several other spinning techniques also exist and may be applied in a limited number of specialized situations. High-molecular-weight polymers, such as those in Spectra@ polyethylene, are formed by solution spinning or gel spinning. As in wet and dry spinning, the polymer is dissolved in a solvent. The polymer and solvent together form a viscous gel that can be processed on conventional melt-spinning equipment to form a gel-like fiber strand. 

Later in the processing, the solvent is extracted and the fibers stretched. Fibers made from polymers that have extremely high melting points and are insoluble present obvious difficulties in spinning. Such materials may be spun by a complex process called emulsion spinning in which small, fibrous polymers are formed into an emulsion, aligned by passing the emulsion through a capillary, then fused or sintered (combined by treating with heat without melting), passed through the spinneret into a coagulating bath, and subsequently stretched. 

DRAWING OR STRETCHING OF POLYMER YARN

Both crystalline and amorphous arrangements of molecules exist within newly formed filaments. It is possible to orient these molecules to make them more parallel to the walls of the filament, and therefore more crystalline and stronger, by stretching the filament before it is completely hardened after polymer spinning. 

Newly formed filaments are, therefore, subjected to drawing or stretching. Depending on the fiber type, this may be done under cold or hot temperature conditions and has the additional effect of making the filament both narrower and longer. Fibers made from polymers that have a low glass transition temperature, such as nylon, can be drawn at room temperature. 

In case of polymer spinning, The polymers are mobile and can be pulled into positions parallel to the fiber length. Polyester, on the other hand, has a higher glass transition temperature and so must be heated to be drawn. Drawing is accomplished by stretching the fibers between two rollers, called Codet rolls, with the second roller rotating faster. 

Not all yarns are drawn to the maximum amount possible, because when a fiber reaches its maximum length, the extensibility of the yarn and fiber are lowered. Yarns that have not been fully drawn are called partially oriented yarns (POY). Those that have been fully drawn are called fully oriented yarns (FOY). Lower speeds in melt spinning produce fibers with lower orientation. As is true of many other textile processes, precise control of the process must be maintained so that the manufacturer can achieve the qualities needed in the final product. 

Other steps may be added, such as texturing (in which crimp is added to the filaments) or heat-setting treatments to ensure very low shrinkage as is required in fibers for automobile tires. Sometimes two or more steps may be combined into consecutive operations to reduce manufacturing costs, so that the fibers may go from spinning directly to drawing or from spinning to drawing to texturing. 

HEAT SETTING AFTER POLYMER SPINNING

Thermoplastic manufactured fibers may shrink when exposed to heat. To prevent shrinkage, such fibers are treated with heat during manufacturing to “set” them into permanent shape. Exposure during use and care to temperatures greater than the heat-setting temperature will counteract the heat setting, resulting in fiber shrinkage or loss of heat-set pleats or creases. 

As the technology for producing manufactured fibers has become more highly developed, manufacturers have turned to increasingly sophisticated techniques for creating new fibers. Different fiber shapes and sizes, as well as unique combinations of polymer types in the same fiber, are but several examples of these techniques. 

Fibre Blends; Properties of fiber Blended Yarns

Fibre Blends 

Fibre Blending is the process of mixing fibers together. As noted earlier, it can take place at any of several points during the preparation of a yarn. The purposes of blending are (1) the thorough intermixing of fibers and/or (2) combining fibers with different properties to produce yarns with characteristics that cannot be obtained by using one type of fiber alone. Self blending of bales of the same fiber is done routinely in processing natural fibers because the fibers may vary from bale to bale. In this type of blending, the mixing of as many bales as possible is done early in the processes preparatory to spinning so that the subsequent steps can help to mix the fiber still more completely. For the same reasons, even when two or more different fiber types are combined, blending is done as early as possible. Carding helps to break up fiber clusters and intermix fibers more thoroughly. However, if the fibers being blended require different techniques for opening, cleaning, and carding, as with polyester and cotton, then slivers can be blended. For blended yarns of different fibers, the blend level is the percentage by weight of each fiber. Blending is not limited to staple-length fibers. Filament fibers of different generic types can be combined into a single yarn. This can be done either by extruding these fibers side by side, during drawing, or during texturing. As described earlier, a blended yarn can be core spun with one fiber at the center and a different fiber as the covering or be wrapped with one fiber making up the central section and another the wrapping yarn. As yarn spinning and texturing technologies grow more sophisticated, we expand the possibilities of combining several different fibers into one yarn. Multiple-input texturing machines can produce specialty yarn blends. 

It should be noted that fabrics woven from two or more yarns each made of different fibers are not considered blends. These fabrics are, instead called combination fabrics. They do not behave in the same way as those fabrics in which, the fibers are more intimately blended and may require special care procedures. Regrettably, the Textile Fibers Products Identification Act (TFPIA) labeling requirements do not distinguish between blended fabrics and combination fabrics when fiber percentage contents of fabrics are given. 

Properties of Blended Yarns 

Fibers with different characteristics, blended into a yarn, can each contribute desirable properties to the final textile material. The ultimate performance is an average of the properties of the component fibers. For example, a fabric of 50 percent cotton and 50 percent polyester would have an absorbency intermediate between that of cotton or polyester. In some cases, however, the observed fabric property is not determined simply by the relative amounts of each fiber in the blend. In blends of nylon with cotton, the tenacity of the blended yarn initially decreases with increasing amounts of nylon because of differences in the breaking elongation of the two fibers. At the breaking elongation of the cotton fibers, the nylon fibers are not assuming their share of the stress, leaving the cotton to bear the load. 

The stage at which blending occurs also affects the properties of the fabrics. In general, the more intimate the mixing of fibers in the blends, the better the resulting properties. Yarns blended at the fiber stage exhibit a more effective averaging of properties than ply-blended yarns. Even though considerable study and evaluation have been made of optimum fiber proportions required to achieve desired results in blends, no certain conclusions have been reached. It is clear that extremely small proportions of fibers have no appreciable influence on performance, although they may have some effect on appearance.

Modern spinning method; Ultra Modern method of manufacturing yarn.

OTHER METHODS OF MANUFACTURING YARNS 

In addition to ring and open-end spinning, techniques that insert true twist into yarn, there are other types of yarn construction. Three of those that have some current commercial application are described in the following sections: false-twist, or self-twist, spinning; yarn wrapping; and splitting or slitting films made from synthetic polymers. The viability of these processes for commercial purposes varies. 

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Air-Jet Spinning 

Air Jet spinning is a ultra modern spinning or yarn manufacturing method The Murata Company, a Japanese firm, has commercialized an air-jet spinning machine that functions as follows. A largely untwisted sliver is fed into the machine. Two nozzles, each forcing an air jet against the sliver from opposite directions, cause fibers from the outer layer of the sliver to wrap around the interior fibers, thereby forming the yarn. 

Hollow Spindle Spinning 

Hollow spindle spinning is another modern yarn manufacturing process. In hollow spindle spinning, a sliver of core fibers is fed through a hollow spindle where it is wrapped by a filament yarn unwinding from the spindle. An interesting application of the technique has been in the manufacture of towels and other fabrics, in which the wrapped yarns are used in the pile. In this instance, the wrapping yarn is made from soluble polyvinyl alcohol (PVA) fibers. After the fabric has been put through the finishing processes, these yarns dissolve, leaving a soft, all-cotton twist less and absorbent yarn in the pile 

Core Spinning 

Core spinning is also a special spinning for yarn manufacturing. Core-spun yarns are usually made with a continuous filament core surrounded by twisted fibers or other yarns. Recently, core spun yarns with a staple core of one fiber and an outer sheath of another fiber have been produced by an adaptation of ring spinning. Two rovings, one of polyester and one of cotton, are fed through drafting rollers and then pass through separate channels before being wound on the spindle. The channel for the cotton sheath is longer, ensuring that it will wrap around the polyester core as the twist is inserted. Fabrics from staple core yarns are more durable and have more easy-care features than those of 100 percent cotton yarns. 

Making Yarns from Films 

Recently, various new techniques have emerged that allow yarns to be formed directly from synthetic polymers without the formation of fibers or the twisting of fibers into yarns. These processes include the formation of yarns by the split-film and slit-film processes. Slit-film yarns could be classified as monofilaments. Yarns made by the split-film process do not fit neatly into the categories of staple or filament yarns. 

Split Films 

In the creation of yarns by the split-film technique, a sheet of polymer is formed. The formed sheet is drawn in the lengthwise direction. Through drawing, the molecules in the polymer are oriented in the direction of the draw, causing the film to be strengthened in the lengthwise direction and weakened in the crosswise direction. This causes a breakdown of the film into a mass of interconnected fibers, most of which are aligned in the direction of the drawing, but some of which also connect in the crosswise direction. The process is known as fibrillation. 

The fibrillated materials can be twisted into strings or twines or other coarse, yarn like materials. The usefulness of split-film yarns is limited because the yarns created are coarse. Olefins are made into split-film yarns for use in making bags, sacks, ropes, and other industrial products. 

Slit Films 

Slit films are made by cutting film into narrow, ribbon like sections. Depending upon the process used for cutting and drawing the film, the tapes may display some degree of fibrillation, like that described for split films. When tapes are made that do not fibrillate, they are flatter and are more suitable for certain uses. Flat tapes are used as warp yarns in weaving and can be made into carpet backings that will be very stable, remaining flat and even. All types of tape yarns are used in making wall coverings, packaging materials, carpet backing, and as a replacement for jute in bags and sacks. 

Lurex@, a flat, ribbon like yarn with a metallic appearance, is a slit film yarn that is often used to add decorative touches to apparel or-household textiles. Lurex@ is made from single or multiple layers of polyester film. Multi-layered types are made by placing a layer of aluminum foil between two layers of polyester film. 

Monoply types are cut from metallized polyester film, protected by a clear or colored resin coating. The natural color of Lurex@ is silver. Other colors are produced by adding pigments to the lacquer coating or to the bonding adhesive. The width of these yarns ranges from 0.069 to 0.010 inch. 

Ply Yarns 

Ply yarns are made from two or more single yarns that are twisted together. Ply yarns are much more expensive than single yarns but are nevertheless often produced to achieve certain benefits. Ply yarns made from identical single yarns are more regular in diameter and are stronger. Ply yarns are often made to achieve particular decorative effects. 

In general, the steps involved in creating ply yarns include: 

1. Winding single yarns and clearing any flaws. 

2. Placing the required number of component yarns alongside each other, in place, ready for supplying to the machine 

3. Insertion of twist to form the ply yarn by any of a number of different machines 

4. Winding the finished yarn on a cone or package for delivery to the customer 

A number of different machines are used in making ply yarns, which may also be referred to as folded yarns. Ring-folding machines, for example, operate on the same principle as ringspinning machines except that instead of a roving being fed to the traveler, the single yarns to be combined are both fed together for twisting.

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Yarn construction; Basic yarn manufacturing process

YARN CONSTRUCTION 

Basic Yarn Manufacturing Processes:
Carding –– Combing –– drafting –– twisting –– winding. 

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As the fibers pass through these processes, they are successively formed into: lap, sliver, roving and finally yarn.
The manufacturing operation in which these stages occurred
(1)Lap to card sliver by the lading process
(2)Card Sliver to Cone sliver by combing process.
(3)Shiver to roving by the drafting, or drawing out process
(4)Roving to yarn by further drafting and twisting process.
(5)Yarn reeled on bobbins, spools or cones by the winding process. 

(1) Bending, Ending, Opening and Cleaning: 
(i) The cotton arrives at the mill in large bales weighing about 500 pounds / 225 kg. The compressed mass of raw fibers must be removed from the bales, blended, opened & cleaned.
(ii) Opening is necessary in order to loosen hard lumps of fibers & disentangle them.
(iii) Cleaning is required to remove trash – such as dirt, leaves, burrs, seeds, etc.
(iv) Blending is necessary to obtain uniformity of fiber quality.
(v) Blending: Mechanical bale pickers pluck thin, even layers of the matted fiber from each of a predetermined number of bales in turn and deposit them on Hooper. The fiber is mixed & passed to an opener.
(vi) Opening: As the mass of fiber passes through the openers, cylinders with protruding fingers open up the lumps & free the trash. The number & kind of cylinder, or beaters, employed depend upon the type of cotton that is being processed.
(vii) Cleaning: As the cotton is opened, trash falls through a series of grid bars. When the cotton emerges from the opener, it still contains small tuffs with about 2/3rd of trash.
(vii) This may be conveyed as a lap, which is loosely entangled mass about 1" thick and about 40" wide. Or it may be fed by chute directly to the card for further cleaning and fiber separation.

Blending

Opening and Cleaning

(2) Carding: 

(i) This is the process of arranging the fibers in a parallel fashion. This is necessary for all staple fibers; otherwise, it would be impossible to produce fine yarns from what is originally a tangled mass.
(ii) Before the raw stock can be made into yarn, the remaining impurities must be removed, the fibers must be disentangled, and they must be straightened.
(iii) The lap is passed through a beater section and drawn on a rapidly revolving cylinder covered with very fine hooks or wire brushes.
(iv) A moving belt of wire brushes slowly moves concentrically above this cylinder. As the cylinder rotate, the cotton is pulled by the cylinder through the small gap under the brushes, the teasing action remove the remaining trash, disentangles the fibers and arranges them in a relatively parallel manner in the form of a thin web.
(v) This web is drawn through a funnel – Shaped device that molds it into a round ropelike mass called the card sliver (about thickness of a broom stick).

Carding

(3) Combing: 
(i) In this operation, fine-toothed combs continue straightening the fibers until they are arranged with such high degree of parallelism that the short fibers called ‘noils’ are combed out and completely separated.
(ii) This procedure is not done when processing man-made staple fibers because they are cut into predetermined uniform length.
(iii) This operation eliminate, as much as 25% of the original card sliver, thus almost one-fourth of the raw cotton becomes waste.
(iv) The combing process forms a comb sliver made of the longest fibers, which, in then, produces a smoother & more even yarn. 

Combing

(4) Drafting / Drawing 

(i) The draw frame has several pairs of rollers, each advance set of which revolves at a progressively faster speed.
(ii) This action pulls the staple lengthwise over each other, thereby producing longer & thinner slivers.
(iii) After several stages of drawing out, the condensed sliver is taken to the slubber, where rollers similar to those in the drawing frame draw out the cotton further.
(iv) The slubbing is passed to the spindles, where it is given its first twist & is then wound on bobbins.

Drawing

(5) Roving: 
(i) Roving is the final product of several drawing out-operation.
(ii) These bobbins are placed on the roving frame, where further drawing out and twisting take place until the cotton stock is about the diameter of a pencil lead
(iii) To this point, only enough twist has been given the stock to hold the fibers together.
(iv) Roving has no tensile strength, it will break apart easily with any slight pull. 

Roving

(6) Spinning: 
(i) The ring spinning frame complete the manufacture of yarn
• By drawing out the roving
• By inserting twist
• By winding the yarn on bobbins.
(ii) Ring Spinning draws; twist s& winds in one continuous process. The traveler carries the yarn as it slides around the ring, thus inserting the twist.