BRIEF STUDY ON THE SEQUENCE OF SHORT STAPLE SPINNING - BLOW ROOM - CARDING - COMBING - DRAWING - SPEED FRAME - RING FRAME - CONE WINDING:-
PRINCIPLES OF SHORT STAPLE SPINNING:-
A yarn is usually of substantial length & of small cross section. In the cross section of a yarn there are usually a multiple number of staple fibers (short fibers) or filaments (long fibers) of unlimited length.
Yarn made out of staple fiber is known as spun yarn, because the staple fibers should undergo number of process stages so that a yarn can be made out of them. This procedure or process stages inn correct sequence is called “spinning”. Fiber extrusion or conversion of filaments from polymers was also considered as “spinning”. Fiber extrusion or conversion of filaments from polymers was also considered as “spinning”. Below mentioned is an introduction to the yarns.
PROCESS SEQUENCE:
Ring spinning:
This type of yarn produced depends on the type and quality of the fiber, the amount of processing carried out and the amount of twist introduced in the yarn.
Cotton system:
The cotton system is used for spinning cotton and staple manmade fibers that are cut to match the cotton fiber length.
Blending:
Bales of the fibers are unwrapped and the fibers are blended to obtain uniformity of fiber quality.
Opening:
The fibers then undergoes an opening process to loosen hard lumps of fiber and disentangle them.
Cleaning:
Fibers are cleaned to remove trash, such as dirt, dust and leaves. Now the fibers are fed directly to the carding machine in the lap form.
Carding:
The lap is then into the carding machine, where the remaining impurities are removed. Fibras are then disentangled, straightened and arranged parallel to each other. The fiber come out in the form of card silver, that is a loose rope-like stand of fibers and wound intro large cans.
Doubling:
Under the doubling process, several silvers are combined to make a narrow lap of compactly placed staple fibers.
Combing:
To make fine yarns, sliver is further straightened under the combing process.
This process straightens the fibers still they are arranged parallel so as to comb out the short fiber called noils from the long ones. This process forms comb sliver made of long fibers so as to produce a smooth and even yarn.
Drawing:
The sliver is blended with sliver of other carding machines to obtain a uniform yarn. It is also drawn out and made thinner and this yarn is known as drawn sliver.
Roving:
The drawn sliver is further drawn out and slightly twisted, this is known as roving and wound on to spools on the roving frame.
Spinning:
Roving is processed on a spinning frame, where the rovings are further drawn out and given a high twist characteristics of spun yarn. The yarn is collected pon spindles and then later wound on to large spools by the process of winding.
BRIEF STUDY ON THE SEQUENCE OF PROCESS INVOLVED AND THEIR FUNCTION
In here we have discussed the process of cotton yarn manufacturing. The initial stage of the spinning process involves converting cotton in bales into the cone winding.
BELOW MENTIONED IS HOW THE MAN-MADE FIBERS MANUFACTURING PROCESS.
First thing in spinning process is converting highly compressed cotton in bales into the form of thoroughly loosened, opened & cleaned.
These steps of processing are carried out in the blow room of a spinning mill. First stage of spinning involves converting lightly compressed cotton bales into the form of opened & cleaned fiber flocks.
Passage of material through,
Blow room
Carding
Combing
Drawing
Speed frame
Cone winding
BLOW ROOM
At this process the fibers in bales form will be loosen, opened & cleaned. This is the starting stage of spinning process. There are three actions happen in blow machine. They are,
Action of opposing spikes
Action of air current
Action of beaters.
1. Action of opposing spikes
The spikes of the evener roller lattice, pick up matted lumps of cotton & take them to the top of the lattice. At this point, they are met by series of spikes of the evener roller. Evener roller rotates in the clockwise direction so that spikes on it oppose any further passage of cotton. Here striking of cotton by spikes of the evener roller takes place, while being held by spikes of evener lattice. Thereby a rough combing action also takes place. The spiked lattice takes part of the cotton with it, while evener lattice is mounted. By this action, the size of the matted cotton lumps is reduced & only a portion on spikes is allowed to go forward. Fiber hanging one roller lattice spikes are pulled in opposing direction & this pulling.
2. Action of air currents
The fan, which is suited at a would below air through the duct b. this would tend to create a vaccum in the trunk c. Air can enter the system only at position d. a low pressure near vaccum is created inside c. this would result in air rushing through d due to atmospheric being higher than that inside the trunck c. the shirley wheel consists of a section of ducting by the insertion of a rotating perforated disc. This disc or wheel rotates at about 70rpm. This is used to seperate cotton , on reaching the shirley wheel, the air is able to pass through the perforations in the wheel causes the cotton is arrested & dropped into the space below. The rotation of the wheel causes the cotton to be carried downwards through a lightly spring loaded control flap e. cotton falls freely under gravity. The fine dust passes with the air through the perforations of the wheel. This is then discharged with air to the dust setting chamber or dust filtration system.
3. Action of beaters
This is the action that is mostly responsible for removing impurities of cotton in blow room. Cotton fibres can be subjected to the striking action of beaters in the following ways.
Striking the cotton while being carried by air currents.
Striking the cotton while being held by a pair of feed rollers or paddles & pedal rollers.
CARDING
Carding is one of the most important operation 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 summarized 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.
Parallelizing and stretching of the fibre.
Transformation of the lap into a sliver, therefore into a regular mass of untwisted fibre.
And in this action you can see two actions. They are,
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.
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:
It is occurred between licker in and cylinder.
There are should be point against back action.
Individualization of fibre is also by this action.
COMBING
Combing is a process which is introduced into the spinning of finer and high quality yarns from cotton. The card materials (sliver) contain certain amount of short fibers, 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 seperated out by using comber.
Objects of comber:
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.
Elimination of remaining impurities.
Elimination of large proportion (not all) of the neps in the fibre.
Formation of sliver having maximum possible evenness.
To straighten the fibres.
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.
Lap feeding by feed roller
Lap nipping by the nipper
Combing by the cylinder
Nipper opening and forwarding
Detaching roller backward movement
Piecing
Combing by the top comb
Detaching roller forward movement
Starting roller forward movement
10. Starting a new cycle
11. Cleaning of cylinder comb
Draw frame
This is the machine on which drafting & doubling are carried out. 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 strands. 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.
Tasks of draw frame
Equalizing
Parallelizing
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 levelling. 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 strands. 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 effects, doubling also provides a degree of compensation of raw material variation by blending. Their results are explained 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 sliver entering the machines.
SPEED FRAME / ROVING FRAME
The product delivered by roving machines is called roving. Roving is a fiber strands of lesser count than that of a sliver. It is also has a small twist to keep fibers together. It is wound on to a package which is suitable for feeding spinning machines.
Objectives of speed frame:
Attenuation of draw sliver to a suitable size for spinning.
To insert a small amount of twist to strengthen the roving.
To wind the twisted strands roving into a bobbin.
Operation involved in speed frame:
Drafting
Twisting
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.
RING FRAME
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.
Functions of ring frame:
Draft the roving the required fineness is achieved
Twist the drafted strand to form yarn of required count and strengthen winding the twisted yarn on to the bobbin for suitable storage, transportation and further processing.
Operations involved in ring frame:
Creeling
Dreafting
Twisting
Winding
Building
Doffing
Some other modern spinning systems:
Open end rotor spinning system
Air jet spinning system
Friction spinning system
Wrap spinning system
Advantage of ring spinning system:
Any type of material (fibre) can be spun
Wide range of count can be processed
It delivers a yarn with optimum characteristics
Idealized twisting system
It is uncomplicated and easy to operate
Higher yarn strength can be achieved
Disadvantages of ring spinning system:
Low production
Machine generates more heat
Limitations:
In ring spinning machine twisting and winding are done simultaneously. That's why the power consumption is higher.
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 personal 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.
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