Yarn spining...

1. 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 : [phone] Ext. 104
Mobile : [phone]
Email : [email protected]

2. 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

3. 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):

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

9. (Draw fram এ যে sliver পাওয়া োয় তা Carding sliver এর যেয়য় অয়েক যেশি 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.

10. 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

11. 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.

12. Roving frame

Roving is an intermediate drafting process required for ring spinning that also places sliver
on to a bobbin (see figure 2.34)

13. 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.

14. 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

15. 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. That’s 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