COTTON YARN MANUFACTURING PROCESS

DIPLOMA IN TEXTILE & APPEREL TECHNOLOGY

SRI LANKA INSTITUTE OF TEXTILE & APPAREL

2014/2015

Name : E.C.Maduranga Ediriweera

Reg , No : DTAT-P/21/2014

Name Of Department : Courtaulds Clothing (PVT) ltd

Name Of Lecturer : Mr.N. P. P .S. K. Pathirana

Date : 21/02/2015

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ACKNOWLEDGEMENT

I would like to express my special thanks of gratitude to my teacher Mr.Panagoda as well as our lecturer who gave me the golden opportunity to do this wonderful project on the topic Cotton yarn manufacturing, which also helped me in doing a lot of Research and i came to know about so many new things I am really thankful to them. Secondly i would also like to thank my parents and friends who helped me a lot in finishing this project within the limited time.

I am making this project not only for marks but to also increase my knowledge. THANKS AGAIN TO ALL WHO HELPED ME.

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CONTENTS PAGES

1. Cotton 41.1 Cotton Production & Harvesting 51.2 Seed Cotton Storage 61.3 Ginning 6-7 2 Cotton Yarn Manufacturing Process 82.1 Textile Yarn Manufacturing 82.2 Carded yarn manufacturing flow chart 92.3 Combed yarn manufacturing flow chart 9-102.4 Blow room 112.4.1 Basic operations involved in the blow room 112.4.2 Objects of blow room 122.4.3 Actions of blow room 122.5 Carding 12-132.5.1 Objects of carding 142.5.2 Tasks of carding 142.6 Draw Frame 142.6.1 Actions Involved in Draw Frame 152.6.2 Tasks of Draw frame 15-162.7 Combing 172.7.1Definition of Combing 172.7.2 Working principle of cotton combing 172.7.3Objectives of Combing 182.8 Speed Frame 182.8.1 Necessity of Speed Frame 182.8.2 Objects/ Functions of Speed Frame 192.8.3 Operations Involved in Simplex Machine 192.9 Ring Spinning 20 2.9.1What is Ring Spinning 20-212.9.2.Objectives of Ring Spinning 222.10 Winding 222.10.1A basic diagram of winding m/c 222.10.2 Following are the tasks of winding  process 233. Yarns 243.1 Definition of Yarn 243.2 Yarn Classification 243.3 Types of cotton yarn 253.4 Differences between card yarn and combed yarn 253.4.1 Carded yarn 253.4.2 Combed yarn 263.5 Yarn Count 263.5.1 Types of yarn count 263.5.2 Indirect count 263.5.3 Direct count 274. Yarn Fault 274.1. Slubs 274.2 Neps 284.3 Thick and Thin plces 294.4 Soft Yarn 304.5 Oil Stained Yarn 314.6 Bad Piecing 324.7 Hairiness 334.8 Foreign Matters 344.9 Spun In Fly 35

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1. Cotton

No one knows exactly how old cotton is. Scientists searching caves in Mexico found

bits of cotton bolls and pieces of cotton cloth that proved to be at least 7,000 years old.

They also found that the cotton itself was much like that grown in America today.

In the Indus River Valley in Pakistan, cotton was being grown, spun and woven

into cloth 3,000 years BC. At about the same time, natives of Egypt’s Nile valley were

making and wearing cotton clothing.

Arab merchants brought cotton cloth to Europe about

800 A.D. When Columbus discovered America in 1492, he found cotton growing in the

Bahamas Islands. By 1500, cotton was known generally throughout the world.

Cotton seed are believed to have been planted in Florida in 1556 and in Virginia

in 1607. By 1616, colonists were growing cotton along the James River in Virginia.

Cotton was first spun by machinery in England in 1730. The industrial revolution

in England and the invention of the cotton gin in the U.S. paved the way for the important

place cotton holds in the world today.

Eli Whitney, a native of

Massachusetts, secured a patent on the cotton gin in 1793, though patent office records

indicate that the first cotton gin may have been built by a machinist named Noah Homes

two years before Whitney’s patent was filed. The gin, short for engine, could do the work

10 times faster than by hand.

The gin made it possible to supply large quantities

of cotton fibres to the fast-growing textile industry. Within 10 years, the value of the U.S.

cotton crop rose from $150,000 to more than $8 million.

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1.1 Cotton Production & Harvesting

After cotton has been harvested, producers who use conventional tillage practices

cut down and chop the cotton stalks. The next step is to turn the remaining residue

underneath the soil surface. Producers who practice a style of farming called conservation

tillage often choose to leave their stalks standing and leave the plant residue on the surface

of the soil.

In the spring, farmers prepare for planting in several

ways. Producers who plant using no-till or conservation tillage methods, use special

equipment designed to plant the seed through the litter that covers the soil surface.

Producers, who employ conventional tillage practices, plow or “list” the land into rows

forming firm seed-beds for planting. Producers in south Texas plant cotton as early as

February. In Missouri and other northern parts of the Cotton Belt, they plant as late as

June.

Seeding is done with mechanical planters which cover as many as 10 to 24 rows at

a time. The planter opens a small trench or furrow in each row, drops in the right amount

of seed, covers them and packs the earth on top of them. The seed is planted at uniform

intervals in either small clumps or singularly. Machines called cultivators are used to

uproot weeds and grass, which compete with the cotton plant for soil nutrients, sunlight

and water.

About two months after planting, flower buds called squares appear on

the cotton plants. In another three weeks, the blossoms open. Their petals change from

creamy white to yellow, then pink and finally, dark red. After three days, they wither and

fall, leaving green pods which are called cotton bolls.

Inside the boll, which is

shaped like a tiny football, moist fibres grow and push out from the newly formed seeds.

As the boll ripens, it turns brown. The fibres continue to expand under the warm sun.

Finally, they split the boll apart and the fluffy cotton bursts forth. It looks like white

cotton candy.

Since hand labour is no longer used in the harvest cotton, the crop is

harvested by machines, either a picker or a stripper. Cotton picking machines have

spindles that pick (twist) the seed cotton from the burrs that are attached to plants’ stems.

Doffers then remove the seed cotton from the spindles and knock the seed cotton into the

conveying system.

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Conventional cotton stripping machines use rollers equipped with alternating bats and

brushes to knock the open bolls from the plants into a conveyor.

A second kind of stripper

harvester uses a broadcast attachment that looks similar to a grain header on a combine.

All harvesting systems use air to convey and elevate the seed cotton into a storage bin

referred to as a basket. Once the basket is full, the stored seed cotton is dumped into a boll

buggy, trailer or module builder.

1.2Seed Cotton Storage

Once harvested, seed cotton must be removed from the harvester and stored before

it is delivered to the gin. Seed cotton is removed from the harvester and placed in

modules, relatively compact units of seed cotton. A cotton module, shaped like a giant

bread loaf, can weigh up to 25,000 pounds.

1.3 Ginning

From the field, seed cotton moves to nearby gins for separation of lint and seed. The

cotton first goes through dryers to reduce moisture content and then through cleaning

equipment to remove foreign matter. These operations facilitate processing and improve

fibre quality. The cotton is then air conveyed to gin stands where revolving circular saws

pull the lint through closely spaced ribs that prevent the seed from passing through. The

lint is removed from the saw teeth by air blasts or rotating brushes, and then compressed

into bales weighing approximately 500 pounds. Cotton is then moved to a warehouse for

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storage until it is shipped to a textile mill for use.

A typical gin will process about 12 bales per hour, while some of today’s more

modern gins may process as many as 60 bales an hour.

1. Module Feeder 11. Conveyor Distributor

2. Suction Telescopes 12. 9000 Feeder

3. Big-J Feed Control 13. 161 Gin Stand

4. Vertical Flow Drier 14. Centrifugal Cleaner

5. Incline Cleaner 15. 24-D Tandem Lint Cleaners

6. Stripper Cleaner 16. Battery Condenser

7. Stick Machine 17. Covered Lint Slide

8. Tower Drier 18. Belt Feeder

9. Incline Cleaner 19. 9300 Up-Packing Universal Density Bale Press

10. Impact Cleaner 20. Bale Tying

21. Bale Bagging And Conveying

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2. Cotton Yarn Manufacturing Process

Yarn manufacturing is a sequence of processes that convert raw cotton fibres into yarn

suitable for use in various end-products. A number of processes are required to obtain the clean,

strong, uniform yarns required in modern textile markets. Beginning with a dense package of

tangled fibres (cotton bale) containing varying amounts of non-lint materials and unusable fibre

(foreign matter, plant trash, motes and so on), continuous operations of opening, blending, mixing,

cleaning, carding, drawing, roving and spinning are performed to transform the cotton fibres into

yarn.

Even though the current manufacturing processes are highly developed,

competitive pressure continues to spur industry groups and individuals to seek new, more efficient

methods and machines for processing cotton which, one day, may supplant today’s systems.

However, for the foreseeable future, the current conventional systems of blending, carding,

drawing, roving and spinning will continue to be used. Only the cotton picking process seems

clearly destined for elimination in the near future.

Yarn manufacturing produces yarns for various woven or

knitted end-products (e.g., apparel or industrial fabrics) and for sewing thread and cordage. Yarns

are produced with different diameters and different weights per unit length. While the basic yarn

manufacturing process has remained unchanged for a number of years, processing speeds, control

technology and package sizes have increased. Yarn properties and processing efficiency are

related to the properties of the cotton fibers processed. End-use properties of the yarn are also a

function of processing conditions.

2.1Textile Yarn Manufacturing

If you want to make a yarn you will have two methods to follow.

One is Carded yarn manufacturing method and another is Combed yarn manufacturing

method.

Carded yarn manufacturing method.

Combed yarn manufacturing method

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2.2 Carded yarn manufacturing flow chart

Combed yarn is most precious, finer and thinner than

the carded yarn. Because the Carded Yarn is produced by following some less manufacturing

steps than the Combed Yarn

Input Material Processing Machines Output Materials

Step 1

Raw Fibre Blow Room Lap

Step 2

Lap Carding Carded Sliver

Step 3

Carded Sliver Draw Frame Draw Frame Sliver

Step 4

Draw Frame Sliver Fly /Speed Frame Roving

Step 5

Roving Ring Spinning Yarn

(Spinning Bobbin)

Step 6

Spinning Bobbin Winding Cone

2.3 Combed yarn manufacturing flow chart

Combed yarn is more precise than card yarn. Here is the process flowchart of Combed

Yarn. The main purpose of Combed yarn manufacturing is to create a yarn which is

highly finer and highly qualified.

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Input Material Processing Machines Output Materials

Step 1

Raw Fibre Blow Room Lap

Step 2

Lap Carding Carded Sliver

Step 3

Carded Sliver Draw Frame 1 Draw Frame Sliver

Step 4

Draw Frame Sliver Sliver Lap Lap

Step 5

Lap Ribbon Lap Ribbon Lap Sliver

Step 6

Ribbon Lap Sliver Comber Combed Sliver

Step 7

Combed Sliver Drew Frame 2 Draw Frame Sliver

Step 8

Draw Frame Sliver Fly /Speed Frame Roving

Step 9

Roving Ring Spinning Yarn

(Spinning Bobbin)

Step 10

Spinning Bobbin Winding Cone

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2.4Blow room

The section where the supplied compressed cotton bale turns into a uniform lap of

particular length by opening, cleaning, blending or, mixing is called blow room section. It

is the first step of spinning. The section consist a number of different machines used in

succession to open and clean the fibres.

2.4.1. Basic operations involved in the blow room:

● Opening- Opening is the first operation in the blow room carried out to the stage of

flocks in the blow room and to the stage of individual fibres in the cards.

● Cleaning- To remove the impurities, foreign materials and the raw materials as clean as

possible.

● Dust removal- To remove the dusts which are completely enclosed in the flocks.

● Blending- To achieve the required quality of yarn by blending different kinds of cotton

into a particular ratio.

●Even feed of the material- To produce a lap of uniform weight per unit length or, to

process the maximum quality which is suitable for carding.

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2.4.2 Objects of blow room:

● Opening- Opening of compressed cotton bales and cotton bales are made into small

tufts.

● Cleaning- To eliminate dust, dirt, broken leaf, seed particles, grass and other foreign

impurities from the fibre.

● Blending/mixing- To produce a comparatively good quality cotton fibre by mixing

different types of cotton together.

● Lap forming-

(a) To convert the opened and cleaned fibre into a sheet of particular width and uniform

weight/unit length is called lap.

(b) To give a cylindrical shape to the pre determined lap by winding it in the lap pin and

to make it suitable for the next process carding.

2.4.3. Actions of blow room:

          (a)  Action of opposite spike(Opening)

          (b) Action of air current(Transport Cleaning) 

          (c)  Action of beater and grid bar(Cleaning and opening)

          (d) Action of regulating motion(Uniform output)

2.5 Carding

Carding is the second stage of cotton spinning. It is defined as the reduction of

entangled mass of fibres to filmy web by working them between two closely spaced

relatively moving surfaces closed with sharp points i.e. wires.

The process of using a card (a

thistle or teasel) for combing textile fibres. This consists of combing or brushing fibres

until they are straightened and placed parallel. For this, the imperfect fibres and other

impurities have to be removed. James Hargreaves and Louis Paul were two of the persons

concerned with this invention and improvements to carding. Since then, innumerable

attempts have been made to improve these machines, but in spite of this and also the latest

improvements made, carding remains essentially the same as established nearly 200 years

ago.

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Since the functions of the card are to place the fibres parallel and

remove other impurities so that perfect fibres can be drawn in sliver, the rollers of carding

machine have to be so arranged, as would perform these functions perfectly.

Carding machine consists of 3 cylinders, covered with cards. (1) Taker-in is

smallest, (2) Main cylinder is the largest and (3) The doffer. The outer contact cylinder lap

feeds cotton to roller C, which rotates on a smooth iron table D. Here all the dirt is

removed, and the fibres are straightened by combing. The cotton then passes along these

cylinders as shown by arrows. The flats further flatten the fibres and also place them loose

but parallel. When these are ultimately fed to doffer, its teeth draw these in light fleece

and these are then further drawn into slivers, and deposited into coiler can G.

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2.5.1 Objects of carding

Opening and cleaning: To open and clean the fibres at single stage.

To make the fibre straight and parallel (Parallelization of fibres)

To remove the small trash particles which have not been taken out from the blow

room line.

To remove the naps and motes.

Individualization of fibres ; i,e. separation of fibres from each others.

Elimination of the remaining impurities.

Attenuation; draft.

To produce thick rope form of fibres called slivers which is suitable for subsequent

processing.

2.5.2 Tasks of carding

Opening of individual fibres.

Elimination impurities.

Elimination of dust.

Disentangling of naps.

Elimination of short fibres. 

Fibre blending.

Fibre orientation.

Sliver formation.

2.6 Draw Frame.

Draw frame is a machine for combining and drawing slivers of a textile fiber (as of hemp

for rope manufacture or cotton for spinning). Drawing is the operation by which slivers

are blended, doubled and leveled. In short staple spinning the term is only applied to the

process at a draw frame.

In drawing slivers are elongated when passing

through a group of pair rollers, each pair is moving faster than previous one.

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2.6.1 Actions Involved in Draw Frame

Drafting

It is the process of increasing length per unit weight of sliver. It is mainly due to

peripheral speed of the rollers.

Doubling

The process of combing two or more carded sliver into a single form is called

doubling. In draw frame m/c generally six slivers are fed to convert into one i.e. six

doubling.

Drawing

In the cotton industry the term is applied exclusively to processing on the draw

frame, where the operation is one of doubling and drafting. Drawing= Drafting +

Doubling.

Diagram of draw frame

2.6.2 Tasks of Draw frame

i. Equalizing

ii. Parallelizing

iii. Blending

iv. Dust removal

i. Equalizing

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One of the main tasks of draw frame is improving evenness over short, medium and

especially long terms. Carded slivers are fed to the draw frame have degree on unevenness

that cannot be tolerated in practice and slivers from the comber contain the “infamous”

piecing. It is obscured by draw frame.

Equalizing is always performed by a first process, namely doubling and can optionally

also be performed by a second process, namely auto leveling. The draft and the doubling

have the same value and lie in the range of 6 to 8.

ii. Parallelizing

To obtain an optional value for strength in the yarn characteristics, the fibers must be

arranged parallel in the fibre strand. The draw frame has the tasks of creating this parallel

arrangement. It fulfils the task by way of the draft, since every drafting step leads to

straightening the fibres.

iii. Blending

In addition to the equalizing effect, doubling also provides a degree of compensation of

raw material variation by blending. Their results are exploited in particular way in the

production of blended yarns comprising cotton or synthetic blends. At the draw frame

metering of the individual components can be carried out very simply be selection of the

number of slivers entering the machines.

iv. Dust Removal

Dust is steadily becoming a greater problem both in processing and for the personnel

involved. It is therefore important to remove dust to the greatest practical extent at every

possible point within the overall process.

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2.7 Combing

2.7.1Definition of Combing

Removing short fibres, neps and impurities by using combs is called combing.It is

the process of separation of long desirable fibres of same length from the short fibres,

neps and all remaining foreign materials of the fibre stuck. The fibres also become straight

and parallel.

2.7.2 Working principle of cotton combing

All the combers operate intermittently, both ends of the fibres are combed

separately by needles and the continuity of the strand is maintained by an ingenious

method of piecing up the separated combed tufts, shortly, the process is operated as

follows –

The lap prepared for combing is fed into the machine between the feed roller and

the bottom nipper. At the front of the nipper, the top nipper is positioned to gripe

the lap as it passes to be combed at the front end of a fringe.

The protruding fibres beyond the nipping point are combed by the passage of raws

of needles fastened of a cylinder and situated below the lap. The cylinder with the

needles revolves and carries away the short fibres, neps, and impurities from the

front part of the fringe. The wastage are removed from the cylinder needles by a

brush and collected around an aspirator.

When the cylinder comb completes its action, the top comb then comes down to

perform its action at the back part of the fibre fringe. Meanwhile, the partly

combed fibres are withdrawn through the top comb by detaching rollers.

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When all the combed fibres have been withdrawn by the detaching roller, the top

comb is withdrawn and the cylinder comb operates on new sets of fibres as before.

The top comb operates again but before the rollers draw away the newly combed

fibres, then turn backwards a little so that, the new fibres can be over lapped with

those withdrawn in the previous combing and in this way the continuity of the

combed web of fibres is maintained.

The combed web delivered by the rollers is passed through a trumpet to

consolidate the fibres and to make a sliver which is pulled along a table alongside

other slivers from the other combers delivered by the same machine. 6 or 8 slivers

are drawn into a single sliver by a drafting mechanism at the end of the sliver table

and passes into a sliver can.

2.7.3 Objectives of Combing

To remove naps in the carded sliver.

To make the fibre more parallel and straight.

To produce a uniform sliver of required per unit length.

To remove the fibre shorter than a predetermined length.

To remove remaining impurities in the comber lap.

2.8 Speed Frame

Simplex is an intermediate process in which fibres are converted into low twist lea

called roving. The sliver which is taken from draw frame is thicker so it is not suitable for

manufacturing of yarn. Its purpose is to prepare input package for next process. This

package is to prepare on a small compact package called bobbins. Roving machine is

complicated, liable to fault, causes defect adds to the production costs and deliver the

product. In this winding operation that makes us roving frame complex. There are two

main basic reasons for using roving frame.

2.8.1 Necessity of Speed Frame:

1. The first reason is related to the required draft. Sliver is a thick, untwisted strand

that tends to be hairy and to create fly. The draft needed to convert this to a yarn is in the

region of 300-500. The drafting arrangements of ring spinning machines, in their current

forms, are not capable of processing this strand in a single drafting operation to create a

yarn of short-staple fibers that meets all the normal demands on such yarns. The fine ,

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twisted roving is significantly better suited to this purpose.

2.The second reason is that draw frame cans represent the worst conceivable mode

of transport and presentation of feed material to the ring spinning frame.

2.8.2 Objects/ Functions of Speed Frame:

1.Attenuation of drawn sliver to form roving of required count by drafting.

2. Insert small amount of twist to give required strength of roving.

3. Wind the twisted roving on to the bobbin.

4. Build the roving in bobbin such a form which will facilitate handling,

withdrawing & transfer to the next process.

2.8.3 Operations Involved in Simplex Machine:

1.Creeling

2.Drafting

3.Twisting

4.Winding

5.Building

6.Doffing

Creeling

To feed the sliver by the help of several rows of driver rollers to the machine.

Creel draft

Creel Stop motion

Block creeling

Drafting

To reduce the wt/unit length of sliver to make it suitable for ring spinning system.

Twisting

To insert small amount of twist to give required strength of roving.

Winding

To wind the twisted roving on to bobbin.

Building

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To build the roving in bobbin such a form which will facilitate handling, withdrawing &

transfer to the next process.

Doffing

To replace an empty bobbin at the place of full roving bobbin.

2.9 Ring Spinning

The Ring Spinning is the most widely used form of spinning machine due to

significant advantages in comparison with the new spinning processes. The ring spinning

machine is used in the textile industry to simultaneously twist staple fibres into yarn and

then wind it onto bobbins for storage. The yarn loop rotating rapidly about a fixed axis

generates a surface referred to as "balloon". Ring frame settings are chosen to reduce yarn

hairiness and the risk of glazing or melting the fibre

2.9.1 What is Ring Spinning?

Ring Spinning is the oldest of the present day spinning processes. Fiber material is

supplied to the ring-spinning machine in the form of roving. The fiber mass of the roving

is reduced by a drafting unit. The twist inserted moves backwards and reaches the fibers

leaving the drafting unit. The fibers lay around one another in concentric helical paths.

The normal forces encountered by the fibers enhance the adhesive forces between the

fibers and prevent fibers from flying or slipping past each other under the tensile strain.

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It is the process of further drawing out roving to the final yarn count

needed, inserting twist to the fibres by means of a rotating spindle and winding the yarn

on a bobbin. These three stages take place simultaneously and continuously.

A mechanically driven

spindle, on which the yarn package firmly sits, is responsible for twist. A stationary ring is

around the spindle, which holds the traveler. Yarn from the drafting unit is drawn under

the traveler, and then led to the yarn package. In order to wind the twisted yarn on a

bobbin tube carried by the spindle, the traveler is required to cooperate with the spindle.

The traveler moves on the ring without any physical drive, but is carried along by the yarn

it is threaded with. The rotation rate of traveler is lower than the spindle, and this

difference in the speeds of traveler and the spindle enables the winding of the yarn on the

tube. A controlled up and down movement of the ring determines the shape of the yarn

package, called Cop or Bobbin. Ring spinning technology provides the widest range in

terms of the yarn counts it can produce.

Ring spinning is a

comparatively expensive process because of its slower production speeds and the

additional processes (roving and winding) required for producing ring spun yarns. Ring

spun yarns produce high quality and are mainly produced in the fine (60 Ne, 10 tex) to

medium count (30 Ne, 20 tex) range, with a small amount produced in the coarse count

(10 Ne, 60 tex) range. End uses include high quality underwear, shirting, towels.The

fibers in the ring yarn are highly parallel and helical in nature, and the fiber arrangement

is uniform along the thickness of the yarn. The yarn has a compact structure, with

essentially no wrapper or hooked fibers. The self-locked structure is the result of intensive

fiber migration, which in turn is influenced by the triangular geometry of the spinning

zone and the high spinning tensions. The high axial strength of the yarn is the result of

unique self-locked structure.

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2.9.2. Objectives of Ring Spinning

To draft the roving fed to the ring spinning frame i,e to convert roving into very fine strand

called yarn.

To impart strength to the yarn by  inserting the necessary amount of twist.

To collect twisted strand called yarn onto handy and transportable package by  winding the

twisted thread on a cylindrical bobbin or tube.

2.10 Winding

In spinning process; winding are the last steps. After winding yarn package are

used for making woven or knitted fabrics. Winding process can be defined as the transfer

of spinning yarn from one package to another large package (cone, spool, cheese, pirn

etc).one the other hand it can be defined as the transfer pf yarn from bobbin, hanks etc

into a convenient from of package containing considerable long length of yarn. A process

of accumulating yarn on a package to facilitate the next process is called as winding.

2.10.1 A basic diagram of winding m/c:

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2.10.2 Following are the tasks of winding  process

Extraction of all disturbing yarn faults such as the short, long thick ,long thin,

spinners doubles, etc

Manufacture of cones having good drawing - off properties and with as long a 

length of yarn as possible

paraffin waxing  of the yarn  during the winding process

introduction into the yarn of a minimum number of knots

achievement of a high machine efficiency i.e high produciton level

The winding process therefore has the basic function of obtaining a larger package

from several small ring bobbins. This conversion process provides one with the possibility

of cutting out unwanted and problematic objectionable faults. The process of removing

such objectionable faults is called as yarn ‘ clearing’ .

Practical experience has proven that winding alters the yarn structure.This

phenomenon does not affect yarn evenness, but affect the following yarn properties

thick places

thin places

neps

hairiness

standard deviation of hairiness

If winding tension is selected properly, the following tensile properties are not affected

tenacity

elongation

work- to- break

But excessive tension in winding will deteriorate the above said tensile properties.

Changes in the yarn surface structure due to winding cannot be avoided. Since the

yarn is accelerated from zero speed to 1200 or 1350 meters per min in a few milli seconds

while being pulled off the bobbin, dragged across several deflection bars and eyelets,

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forced into a traverse motion at speed that make it invisible, and finally rolled up into a

firm construction called package or cone.

3.Yarns 3.1 Definition of Yarn

A yarn is a constructed assemblage of textile fibers which acts as a unit in fabric

formation.

3.2 Yarn Classification

1. Staple Fiber Yarns or Spun Yarns(single yarn):

Spun yarns are made by mechanical assembly and twisting together(spinning) of staple

fibers. Ring spinning, Rotor spinning, Wrap spinning, Air-jet spinning etc. machines are

used to produced this spun or single yarns.

2. Ply Yarn:

Single yarns are used in the majority of fabrics for normal textile and clothing

applications, but in order to obtain special yarn features, particularly high strength and

modulus for technical and industrial applications, ply yarns are often needed. A folded  or

ply yarn is produced by twisting two or more single yarns together in one operation, and a

cabled yarn is formed by twisting together two or more folded yarns or a combination of

folded and single yarns. The twisting together of several single yarns.

 

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Increases the tenacity of the yarn by improving the binding-in of the fibers on the

outer layers of the component single yarns. Ply yarns are also more regular, smoother and

more hard wearing. The direction of twisting is designated as S or Z, just as in single

yarns. Normally the folding twist is in the opposite direction to that of the single yarns.

3. Filament Yarns:

A filament yarn is made from one or more continuous strands called filaments

where each component filament runs the whole length of the yarn. Those yarns composed

of one filament are called monofilament yarns, and those containing more filaments are

known as multifilament yarns. For apparel applications ,a multifilament yarn may contain

as few as two or three filaments or as many as 50 filaments. In carpeting, for example, a

filament yarn could consist of hundreds of filaments, Most manufactured fibers have been

produced in the form of a filament yarn. Silk is the only major natural filament yarn.

3.3 Types of cotton yarn

 There are two types of cotton yarn according to their manufacturing process,

 

1. Carded yarn.

2. Combed yarn.

3.4 Differences between card yarn and combed yarn.

 3.4.1 Carded yarn

 The yarn is more hairy.

The yarn is more irregular.

The yarn is cheaper.

The yarn is less shiny.

Some trash may be present in the yarn.

Neaps can be present in the yarn.

Possibility of irregular twist distribution in the yarn.

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3.4.2 Combed yarn

 

The yarn is less hairy.

The yarn is more regular.

The yarn is more costly.

The yarn is shinier.

No trash can be present in the yarn.

Neaps are not available in the yarn.

3.5 Yarn Count

The yarn count is a numerical expression which defines its fineness or coarseness. It also

expresses weather the yarn is thick or thin. A definition is given by the textile institute – “Count is

a number which indicates the mass per unit length or the length per unit mass of yarn

3.5.1 Types of yarn count:

         Indirect system - English, Metric, Worsted.

         Direct system - Tex, Denier, Lbs/Spindle.

3.5.2 Indirect count

The count of yarn expresses the number of length units in one weight unit. Thus higher

the count, finer the yarn. The system is generally used for cotton, worsted, linen (wet

spun) etc.

English system

It is defined as the number of hanks 840 yds per pound is called yarn count

Metric system

It is defined as the number of hank (1000m) per kg.

Worsted system

It is defined as the number of hanks (540yds) per pound.

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3.5.3 Direct count

The count of yarn expresses the no. of weight units in one length unit. Thus higher the

count, coarser the yarn. The system is generally used for synthetic fibre, jute, silk etc.

Tex system or, Lea count

It is defined as the weight in grams of 1000m is called tex count.

Denier

The number or, count in the denier system is the weight in grams of 9000m.

Decitex

weight in grams of 10000 meter

4. Yarn Fault

4.1 Slubs

An abnormally thick place or lump in yarn showing less twist at that place.

EFFECT

More end breaks in the next process.

Damaged fabric appearance.

Shade variation in dyed fabrics.

CAUSES

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Accumulation of fly and fluff on the machine parts.

Poor carding.

Defective ring frame drafting and bad piecing

Improperly clothed top roller clearers.

RECTIFICATION

Machine surfaces to be maintained clean.

Proper functioning of pnemafil/roller clearers to be ensured.

Broken teeth gear wheel to be avoided and proper meshing to be ensured.

Better fiber individualisation at cards to be achieved.

Optimum top roller pressure &back zone

Setting at ring frame to be maintained.

4.2 Neps

Yarn containing rolled fibre mass, which can be clearly seen on black board at close

distance; measurable on Uster imperfection Indicator.

EFFECT

Damaged fabric appearance

Shade variation in the dyed fabrics

An abnormally thick place or lump in yarn showing less twist at that place is

called slubs

CAUSES

Accumalation of fly and fluff on the machine parts

Poor carding.

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Defective ring frame drafting and bad piecing

Improperly clothed top roller clearers.

RECTIFICATION

Machine surfaces to be maintained clean.

Proper functioning of pnemafil/roller clearers to be ensured.

Broken teeth gear wheel to be avoided and proper meshing to be ensured.

Better fiber individualisation at cards to be achieved.

4.3 Thick and Thin Plces

Measurable by Uster Imperfection Indicator and observable on appearance

EFFECT

Eccentric top and bottom rollers

Insufficient pressure on top rollers

Worn and old aprons and improper apron spacing

Improper meshing of gear wheels

Mixing of cottons varying widely in fiber lengths and use of immature cottons

CAUSES

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Eccentric top and bottom rollers

Insufficient pressure on top rollers

Worn and old aprons and improper apron spacing

Improper meshing of gear wheels

Mixing of cottons varying widely in fibre lengths and use of immature cottons

RECTIFICATION

Eccentric top and bottom rollers to be avoided

Top arm pressure checking schedules to be Maintained strictly

Wide variation in the properties of cottons used in the mixing to be avoided

Better fiber individualisation at cards to be achieved.

Correct spacers to be utilised

4.4 Soft Yarn

Yarn which is weak indicating lesser twist

EFFECT:

More end breaks in subsequent processes

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Shade variation in dyed fabrics

CAUSES:

Slack tapes dirty jockey pulleys

Improper bobbin feed on the spls

Less twist in the yarn

Bad clearing at the travellar

RECTIFICATION:

Vibration of bobbins on the spindles to be avoided

Proper yarn clearing to be ensured

Periodic replacement of worn rings and travellars to be effected

4.5 Oil Stained Yarn

Yarn stained with oil

EFFECT

Damaged fabric appearance

Occurrence of black spot in fabric

CAUSES

Careless oil in the moving parts,over head pulleys etc

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Piecings made with oily or dirty fingers

Careless material handlings

RECTIFICATION

Appropriate material handling procedures to be followed

Oilers to trained in proper method of lubrication

Clean containers to be utilised for material transportation

4.6 Bad Piecing

Unduly thick piecing in yarn caused by over End piecing

EFFECT

More end breaks in subsequent process

Increase in hard waste

CAUSES

Wrong method of piecing and over end piecing

Twisting the ends instead of knotting

RECTIFICATION

Tenters to be trained in proper methods of piecing

Separators to be provided

Excessive end breaks in spinning to be avoided

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4.7 Hairiness

Protrusion of fibre ends from the main yarn structure

EFFECT

More end breaks in winding

Uneven fabric surface

Beads formation in the fabric in the case of polyester/cotton blends

CAUSES

Use of cottons differing widely in the properties in the same mixing

Use of worn rings and lighter travellars

Maintaining low relative humidity, closer roller settings and very high spindle

speeds

RECTIFICATION

Use of travellars of correct size and shape and rings in good condition to be ensured

Periodic replacement of travellars and suitable

Roller settings to be maintained

Optimum relative humidity to be maintained in the spinning room

Wide variation in the properties of cottons used in the mixing to be avoided

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4.8 Foreign Matters

Metallic parts, jute flannel and other similar foreign matters spun along with yarn

EFFECT

Breaks during winding

Formation of holes and stains in cloth

Damaged fabric appearance

CAUSES

Improper handling of travellers

Improper preparation of mixings

RECTIFICATION

Removal of foreign matters(such as jute fibres,colour cloth bits) to be ensured during

preparation of mixing

Installation of permanent magnets at proper

Places in blow room lines to be ensured

4.9 Spun In Fly

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Fly or fluff either spun along with the yarn or loosely embedded on the yarn

EFFECT

More breaks in winding

CAUSES

Accumulation of fluff over machine parts

Fanning by workers

Failure of over head cleaners

Malfunctioning of humidification plant

RECTIFICATION

Machinery surfaces to be kept clean by using roller pickers

Fanning by workers to be avoided

Performance of over head cleaners and humidification plants to be closely

monitored

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