Process flow chart of Cotton Yarn Spinning

Yarn:

A yarn is a continuous and uniform mass of fibres bounded together by the insertion

of twist. Yarns are raw material of the fabric. The thickness of the yarn varies to a

wide range. Normally, the thickness of a yarn is expressed in terms of count. Count

may be defined as the number which expresses the fineness or coarseness of a yarn.

The yarns may be spun from staple fibre or continuous filaments. Normally majority

yarns are produced from staple fibre. To produce yarns from staple fibres, a wide

range of machines are needed, called spinning machines.

Count= Weight per unite length

Spinning:

The cotton fiber grows in the seedpod or boll, of the cotton plant. Each fiber is a

single elongated cell that is flat, twisted, and ribbon like with a wide inner hollow

(lumen). It is composed of about 90 percent cellulose and about 6 percent moisture;

the remainder consists of natural impurities. The outer surface of the fiber is covered

with a protective wax like coating which gives the fiber a somewhat adhesive

quality. After this hydraulic pressing is done and cotton is been tested for the quality

control. And then it has been sent for even moisture distribution. After all these

Md. Shalehur Rahman Samy Associate Consultant, SAP MM

IPE, SUST.

Tel : +8809612124545 Ext. 104

Mobile : +8801725444492

Email : shalehur@gmail.com

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processes this bale cotton gone to traders and textile mills receives these bale cotton

from traders. As soon as the cotton arrives at the mill after ginning process in large

bales weighing about 500 pounds (225 kg) each it is been kept for 24hours.

Yarn spinning

Process flow of Cotton Yarn

Step-1: Blow room machine

Step-2: Carding machine

Step-3: Drawing

Step-4: Combing

Step-5: Roving

Step-6: Ring Spinning

Step-7: Cone Winding

Step-1: Blow room machine Operations in the Blow-room

1. Opening 2. Cleaning 3. Dust Removal 4. Blending 5. Even feed of material to the card

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Opening The first operation required in the blowroom line is opening, carried out to the stage of tufts in

contrast to the cards, where it is performed to the stage of individual fibers. Tuft weight can be

reduced to about 0,1 mg in the blowroom. The small improvements by each of the subsequent

machines are obtained only by considerable additional effort, stressing of the material, unnecessary

fiber loss and a striking increase in neppiness. If necessary the card is able to assume rather more of

the overall task.

Cleaning It has to be kept in mind that impurities can only be eliminated from surfaces of tufts. Within a

progressive line of machines it is therefore necessary to create new surfaces continuously by opening

the material. And even then the best blowroom line is not able to eliminate all, or even almost all, of

the foreign matter in the raw material. A blowroom installation removes approximately 40 - 70% of

the impurities. The result is dependent on the raw material, the machines and the environmental

conditions.

It is clear from this diagram that the cleaning effect cannot and should not be the same for all

impurity levels, since it is easier to remove a high percentage of dirt from a highly contaminated

material than from a less contaminated one. Looking at the machine, the cleaning effect is a matter

of adjustment. Increasing the degree of cleaning also increases the negative effect on cotton when

trying to improve cleaning by intensifying the operation, and this occurs mostly exponentially.

Therefore each machine in the line has an optimum range of treatment. It is essential to know this

range and to operate within it.

In an investigation saw that the quantity of waste eliminated on a cleaning machine by modifying

settings and speeds was raised from 0.6% to 1.2%: while the quantity of foreign matter eliminated

increased by only 41%, the quantity of fibers eliminated increased by 240%. Normally, fibers

represent about 40 - 60% of blowroom waste. Thus, in order to clean, it is necessary to eliminate

about as much fibers as foreign material. Since the proportion of fibers in waste differs from one

machine to another, and can be strongly influenced, the fiber loss at each machine should be known.

It can be expressed as a percentage of good fiber loss in relation to total material eliminated, i.e. in

cleaning efficiency (CE):

AT = total waste (%); AF = good fibers eliminated (%).

For example, if AT = 2.1% and AF = 0.65%:

Dust Removal Almost all manufacturers of blowroom machinery now offer dust-removing machines or equipment

in addition to opening and cleaning machines. However, dust removal is not an easy operation, since

the dust particles are completely enclosed within the flocks and hence are held back during suction

(because the surrounding fibers act as a filter). Since, as shown it is mainly the suction units that

remove dust (in this example 64%), dust removal will be more intensive the smaller the tufts.

It follows that dust elimination takes place at all stages of the spinning process.

Blending Blending of fiber material is an essential preliminary in the production of a yarn. Fibers can be

blended at various stages of the process. These possibilities should always be fully exploited, for

example by Transverse doubling transverse doubling. However, the start of the process is one of the

most important stages for blending, since the individual components are still separately available and

therefore can be metered exactly and without dependence upon random effects. A well-assembled

bale layout and even (and as far as possible simultaneous) extraction of fibers from all bales is

therefore of the utmost importance. Simultaneous extraction from all bales, which used to be normal

in conventional blending batteries, is now no longer possible (automatic bale openers). Accordingly,

intensive blending in a suitable blending machine must be carried out after separate tuft extraction

from individual bales of the layout. This blending operation must collect the bunches of fibers

arriving sequentially from individual bales and mix them thorough.

Even Feed of Material to the Card Finally, the blowroom must ensure that raw material is evenly delivered to the cards. Previously, this

was carried out by means of precisely weighed laps from the scutcher, but automatic tuft feeding

installations are used nowadays. While in the introductory phase such installations were subject to

problems regarding evenness of tuft delivery, today they generally operate well.

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Step-2: Carding machine

Carding Carding is one of the most important operations in the spinning process as it directly determines the

final features of the yarn, above all as far as the content of neps and husks are concerned. There are

many objectives of the carding process and these can be summarised as:

Opening the tufts into individual fibres;

Eliminating all the impurities contained in the fibre that were not eliminated in the previous

cleaning operations;

Selecting the fibres on the basis of length, removing the shortest ones;

Removal of neps;

Parallelising and stretching of the fibre;

Transformation of the lap into a sliver, therefore into a regular mass of untwisted fibre.

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Fig.A Section view of the card with hopper

The carding operation is carried out by the card, a machine that in practice is a system of rotating

organs, mobile and fixed flats, covered with steel spikes that go by the name of wiring. It is a good

idea to know what the wiring and its functions are before going onto a description of the card.

And in this action you can see two actions. They are;

1. Carding Action 2. Stripping Action

1. Carding Action When two close surfaces have opposite wire direction and their speed direction or relative

motion is also opposite. Then the action between two surfaces is called carding action.

Functions:

It is occurred between flats and cylinder.

Maximum individualization of fibers is achieved in this region.

Naps short fibers dirt and dust are removed by this action.

There always should be point against point action.

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Carding Action

2. Stripping Action When two close surfaces have same wire direction and their speed direction or relative motion is

opposite then the action between two surfaces is called stripping action.

Functions:

1. It is occurred between licker in and cylinder. 2. There are should be point against back action. 3. Individualization of Fibre is also by this action.

Step-3: Drawing

Draw Frame This is the machine on which drafting & doubling are carried out. Drawing is also called Drafting.

Carded sliver is that they are not even (uniform) enough to produce to good quality yarns.

Therefore, usually all the carded slivers are subjected to Doubling & Drafting on a machine called

Draw Frame. Doubling is the practice of feeding two or more strands to produce one Strand. To attenuate fiber laps to slivers, Drafting is carried out. Different methods are used to draft sliver or yarn. One method is called Roller Drafting. During drafting the number of fibers in the cross section of the sliver or lap is reduce.

Draw frame

Tasks of Draw frame

1. Equalizing 2. Parallelizing 3. Blending

Equalizing: 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.

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

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

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

the fibers.

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.

(Draw fram sliver Carding sliver uniform)

Step-4: Combing

Combing Combing is a process which is introduced into the spinning of finer and high quality yarns

from cotton. The carded materials (sliver) contain certain amount of short fibres, neps, fine

kitty and leaf particles. Short fibres are a hindrance to spinning of finer counts where the

number of fibre in the cross section of the yarn is less. The short fibres cause thick and uneven

places in the yarn length and the yarn looks hairy. Apart from this, very short fibres do not

contribute anything to yarn strength. Short fibres below a certain pre-determined length can be

easily separated out by using comber.

Objects of Comber:

1. To remove the short fibres below a pre-selected length so that the spinner enable to produce finer or better quality of yarn that cannot be possible in carding state.

2. Elimination of remaining impurities. 3. Elimination of large proportion (not all) of the neps in the fibre. 4. Formation of sliver having maximum possible evenness. 5. To straighten the fibres.

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Basic Principle of a Comber (Combing sequence/Cycle): One article has written about basic principle of a comber. So here only title of comber

principle is given below.

1. Lap feeding by feed roller 2. Lap nipping by the nipper 3. Combing by the cylinder 4. Nipper opening and forwarding 5. Detaching roller backward movement 6. Piecing 7. Combing by the top comb 8. Detaching roller forward movement 9. Starting a new cycle 10. Cleaning of cylinder comb

Combing machine diagram

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Step-5: Roving

Roving Frame / Speed Frame The product delivered by roving machines is called Roving. Roving is a Fibre strand of lesser count

than that of a sliver. It is also has a small twist to keep Fibres together. It is wound on to a package

which is suitable for feeding spinning machines.

Objectives of speed frame

1. Attenuation of draw sliver to a suitable size for spinning. 2. To insert a small amount of twist to strengthen the roving. 3. To wind the twisted strand roving into a bobbin.

Operation involved in speed frame:

1. Drafting 2. Twisting 3. Winding

Drafting: To reduce the weight /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.

Roving frame

Roving is an intermediate drafting process required for ring spinning that also places sliver

on to a bobbin (see figure 2.34)

Step-6: Ring Spinning

Ring Frame

There are three main technologies available for inserting this twist for the purpose of creating

a yarn structure. These are ring spinning, open end (or rotor) spinning, and air jet (vortex)

spinning.

Ring spinning

Ring spinning inserts twist by means of a rotating spindle (see figure 2.35). Ring spinning is

both the slowest spinning method and the most expensive because of the additional processes

required (roving and winding).

Figure 2.35: Diagram of a ring spinning operation

Ring spinning produces the strongest, finest, and softest yarn (see figure 2.36). It is also the

most mature spinning technology.

The ring spinning machine was first invented in 1828 by the American Thorp. In 1830,

another American scientist, Jenk, contributed the traveler rotating on the ring. There have been

many development has done in ring spinning machine for the last years but the basic concept

remained unchanged.

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Ring spinning machine

Functions of ring frame:

1. Draft the roving until the required fineness is achieved 2. Twist the drafted strand to form yarn of required count and strength 3. Winding the twisted yarn on to the bobbin for suitable storage, transportation and

further processing.

Operations involved in ring frame:

1. Creeling 2. Drafting 3. Twisting 4. Winding 5. Building 6. Doffing

Some other modern spinning systems:

1. Open end rotor spinning system 2. Air Jet spinning system 3. Friction spinning system 4. Wrap spinning system

Advantage of Ring Spinning System:

1. Any type of material (Fibre) can be spun 2. Wide range of count can be processed

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3. It delivers a yarn with optimum characteristics. 4. Idealized twisting system 5. It is uncomplicated and easy to operate 6. Higher yarn strength can be achieved

Disadvantages of Ring Spinning System:

1. Low production 2. Machine generates more heat

Limitations: In ring spinning machine twisting and winding are done simultaneously. Thats why the power

consumption is higher.

Step-7: Cone Winding

Cone Winding This is the final stage in Spinning & that is Cone Winding. As nowadays good winding is the

mirror of spinning mills, it is necessary that this process is understood very well by all the

personnel handling the department. Yarn winding can thus be viewed as simply being a

packaging process, forming a link between the last few elements of yarn manufacturing and

the first element of fabric manufacturing process. Improper utilization of the features of the

winding machine can not only cost heavily to the spinning mills, but it can also lead to loss of

good customers permanently.

Cone Winding Machine

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