Textile & Fashion World

Twist:

Twist is the number of turns about its axis per unit of length of a yarn or other textile strand. Twist is expressed as turns per inch (tpi), turns per meter (tpm), or turns per centimeter (tpcm). It is a very essential process in the production of staple yarn, twine, cord and ropes. Twist is inserted to the staple yarn to hold the constituent fibres together, thus giving enough strength to the yarn, and also producing a continuous length of yarn. The mechanism of twist insertion to the strand during ring spinning has been studied. The twisting of the strand occurs not only due to the rotation of twisting elements, but also due to the winding of yarn on the package. When the yarn is wound on a stationary cop by gripping and winding the yarn by hand, for every coil of yarn wind one turn of twist to the yarn is inserted. Now we will discuss about way of twist insertion to the yarn. 

Twist Insertion to the Yarn When the Spindle is Stationary:  

We assume that the spindle is stationary and the traveller rotates in the ring frame. Each revolution of the traveller winds one coil of yarn onto the cop. This is similar to gripping and winding the yarn on a cop by hand. The yarn will rotate 3600 per coil wind while winding the yarn onto a stationary cop by hand; hence the winding causes yarn twisting.

• Length of yarn wound per revolution of traveller = πd
• Turns/cm due to winding = 1/πd

Where d – Winding on diameter of cop or bobbin in cm.

If the yarn is unwound in parallel from the cop, the yarn will retain all the twists present in the yarn, whereas if the yarn is over-end unwound, unwinding a coil removes one turn of twist. The unwinding causes twisting. So, the twists inserted into the yarn during winding are removed during over-end unwinding. The over-end withdrawal may be from any side of the cop. If the traveller rotates in a clockwise direction to wind the yarn onto the cop, each coil of wind inserts one turn of ‘Z’ twist to the yarn. When the same is over-end unwound, every unwinding coil inserts one turn of twist in an ‘S’ direction, and so the resultant yarn will not have any twist.

Twist Insertion into the Yarn when the Traveller is Stationary:  

• Turns/cm due to over-end unwinding = 1/πd

The direction of twist insertion during over end unwinding depends on direction of yarn winding. If the spindle rotates in an anticlockwise direction to wind the yarn onto the cop, during over-end unwinding a ‘Z’ twist will be inserted into the yarn. But if the same yarn is unwound in parallel, the yarn will not receive any twist.

Twist Insertion onto the Yarn when both Spindle and Traveller rotate in Opposite Direction:
It may be wondered why it should be necessary to rotate the traveller and spindle in the opposite direction, and also how to rotate the traveller in the opposite direction. This is only to enable the reader to clearly understand the mechanism of twisting. When both the spindle and traveller rotate in the opposite direction, each revolution of the spindle and traveller winds one coil each. The length of yarn wound per min and twist/cm can be calculated.

• Length of yarn wound per min = π d (NS+NT)
• Twist/cm due to winding = - NT/ π d (NS+NT) where
• NS – spindle speed in rpm,
• NT – traveller speed in rpm.

If the spindle and traveller rotate in clockwise and anticlockwise directions respectively, the direction of twist insertion due to winding would be ‘S’. But during over-end unwinding, the direction of twist insertion would be ‘Z’. + and - signs are used to represent the Z and S twist directions respectively.

• Twist/cm due to over-end unwinding = (NT/ π d (NS+NT)) + (NS/ π d (NS+NT))
• Twist/cm in the yarn after over-end withdrawal = (NS/ π d (NS+NT)

Twist Insertion onto the Yarn when the Spindle leads the Traveller:
In ring spinning, both the spindle and traveller rotate in the same direction. However, the spindle rotates at a higher speed than the traveller. If both rotate at the same speed, only the twisting of yarn takes place without winding. Due to the difference in their rotational speeds, the winding of the yarn takes place on the cop.

• Length of yarn wound on the cop per min = πd (NS –NT)

Due to rotation, both spindle and traveller insert twists onto the yarn. If both the spindle and traveller rotate in a clockwise direction, a ‘Z’ twist is inserted to the yarn.

• Turns/cm in the yarn = NT/πd (NS –NT)
• The winding rate should be equal to the delivery rate.
• Length of yarn delivered (cm/min) = πd (NS –NT)

Here winding takes place in similar conditions to when the traveller is stationary and the spindle is rotating; hence winding does not insert any twist onto the yarn. On the other hand, during over-end unwinding one turn of twist is inserted for every unwound [[*]] of coil.

• Turns/cm for unwinding = 1/πd
• Total twist present in the yarn after over-end unwound = NT/πd(NS –NT) + 1/πd = NS/πd(NS-NT)

Since yarn from the ring cop is normally over-end withdrawn during the winding process, the spindle speed is taken for calculating the turns/cm in the yarn instead of using traveller speed. However, turns/cm in the roving is calculated by taking the flyer speed into account. This is due to the parallel withdrawal of roving during spinning.

Twist Insertion onto the Strand when Flyer leads Bobbin:
Due to the difference in the speeds of the flyer and the bobbin, the winding of roving takes place on the bobbin.

• Twist/cm due to twisting = NB / πd(NF-NB)
• Twist/cm due to winding = (NF-NB)/ πd(NF-NB)
• Twist/cm in the roving = NF / πd(NF-NB) where
• NF - flyer speed in rpm,
• NB - bobbin speed in rpm.

If the roving is unwound in parallel, the roving will have the same amount of twist as in the bobbin, but if it is over-end withdrawn, it will lose a certain amount of twist during unwinding.

• Turns/cm due to over-end withdrawal = - (NF-NB)/ πd(NF-NB)
• Turns/cm in the roving after over-end withdrawal = NB/πd (NF-NB) 

  http://textilelearner.blogspot.com/2012/05/mechanism-of-twist-insertion-to.html

Blow Room Line:

Convensional Blow Room Line:

Flow Chart of Blow Room(Conventional)

Hopper bale opener

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Ultra cleaner or step cleaner

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Vertical or twine opener or cleaner

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Hopper feeder-1

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Porcupine opener

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Hopper feeder-2

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Scutcher

Flow Chart of Blow Room(Modern)

Bale plucker

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Metal detector

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Uniclean

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Unimix

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Uni flex 

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Vision shield 

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Condenser

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Chute feed

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Carding

Blowroom consists a number of machines used on succession to open and clean the cotton fibre. Since the tuft size of cotton becomes smaller and smaller, the required intensities of processing necessitates different machine configuration.

Objects of Blowroom: 

1. Opening:

a) To open the compressed bales of fibres.

b) To make the cotton tuft as small as far as possible.

2. Cleaning:

To remove dirt, dust, broken seeds, broken leaves, and other foreign materials from the fibre.

3. Mixing & Blending:

To make good value of yarn and to decrease production cost mixing and blending is done.

4. Lap or flocks formation:

To transfer opened and cleaned fibre into sheet form of definite width and length which is called lap or in modern system directly feed to the carding machine into flocks form.

Basic Operations in the Blowroom:

Blow room installations consists of a sequence of different machines to carry out the above said  operations.Moreover Since the tuft size of cotton becomes smaller and smaller, the required intensities of processing necessitates different machine configuration. 

Technological Points in Blowroom 

Opening in blowroom means opening into small flocks.Technological operation of opening means the volume of the flock is increased while the number of fibres remains constant. i.e. the specific density of the material is reduced 

The larger the dirt particle , the better they can be removed . Since almost every blowroom machine can shatter particles, as far as possible a lot of impurities should be eliminated at the start of the process.Opening should be followed immediately by cleaning, if possible in the same machine. 

The higher the degree of opening, the higher the degree of cleaning. A very high cleaning effect is almost always purchased at the cost of a high fibre loss. Higher roller speeds give a better cleaning effect but also more stress on the fibre. 

Cleaning is made more difficult if the impurities of dirty cotton are distributed through a larger quantity of material by mxing with clean cotton.The cleaning efficiency is strongly dependent on the TRASH %. It is also affected by the size of the particle and stickyness of cotton. Therefore cleaning efficiency can be different for different cottons with the same trash %. There is a new concept called CLEANING RESISTANCE. Different cottons have different cleaning resistance.

If cotton is opened well in the opening process, cleaning becomes easier because opened cotton  has more surface area, therefore cleaning is more efficient . If automatic bale opener is used, the tuft size should be as small as possible and the machine stop time should be reduced to the minimum level possible .

If Manual Bale openers are used, the tuft size fed to the feed lattice should be as small as possible .Due to machine harvesting , cotton contains more and more impurities, which furthermore are shattered by hard ginning. Therefore cleaning is always an important basic operation. 

In cleaning, it is necessary to release the adhesion of the impurities to the fibres and to give hte particles an opportunity to separate from the stock. The former is achieved mostly by picking of flocks, the latter is achieved by leading the flocks over a grid. 

Using Inclined spiked lattice for opening cotton in the intial stages is always a better way of opening the cotton with minimum damages. Ofcourse the production is less with such type of machines. 

But one should bear in mind that if material is recyled more in the lattice, neps may increase. Traditional methods use more number of machines to open and clean natural fibres. Mechanical action on fibres causes some deterioration on yarn quality, particularly in terms of neps . Moreover it is true that the staple length of cotton can be significantly shortened . Intensive opening in the initial machines like Bale breaker and blending machines means that shorter overall cleaning lines are adequate. 

In a beating operation, the flocks are subjected to a sudden strong blow. The inertia of the impurities accelerated to a high speed, is substantially greater than that of the opened flocks due to the low air resistance of the impurities. The latter are hurled against the grid and because of their small size, pass between the grid bars into the waste box, while the flocks continue around the periphery of the rotating beater. By using a much shorter machine sequence, fibres with better elastic properties and improved spinnability can be produced. 

Air streams are often used in the latest machine sequence, to separate fibres from trash particles by buoyancy differences rather than beating the material against a series of grid bars. There are three types of feeding apparatus in the blowroom opening machines two feed rollers( clamped) feed roller and a feed table a feed roller and pedals 

Two feed roller arrangements gives the best forwarding motion, but unfortunately results in greatest clamping distance between the cylinders and the beating element feed roller and pedal arrangement gives secure clamping throughout the width and a small clamping distance, which is very critical for an opening machine In a feed roller and table arrangement, the clamping distance can be made very small. This gives intensive opening, but clamping over the whole width is poor, because the roller presses only on the highest points of the web. 

Thin places in the web can be dragged out of hte web as a clump by the beaters Honeydew(sugar) or stickiness in cotton affect the process very badly. Beacause of that production and quality is affected. Particles stick to metal surfaces, and it gets aggreavated with heat and pressure. These deposits change the surface characteristics which directly affects the quality and running behavior.

There are chemicals which can be sprayed to split up the sugar drops to achieve better distribution.But this system should use water solutions which is not recommended due to various reasons. It is better to control the climate inside the department when sticky cotton is used. Low temperature ( around 22 degree Celsius) and low humidity (45% RH). This requires an expensive air conditioning set up. 

The easiest way to process sticky cotton is to mix with good cotton and to process through two blending machines with 6 and 8 doublings and to install machines which will seggregate a heavier particles by buoyancy differences.

General factors which affect the degree of opening , cleaning and fibre loss are, 

Cotton contains very little dust before ginning. Dust is therefore caused by working of the material on the machine. New dust is being created through shattering of impurities and smashing and rubbing of fibres.  However removal of dust is not simple. Dust particles are very light and therefore float with the cotton in the transport stream.Furthermore the particles adhere quite strongly to the fibres. If they are to be eliminated they are to be rubbed off.The main elimination points for adhering dust therefore, are those points in the process at which high fibre/metal friction or high fibre/fibre friction is produced. 

Removal of finest particles of contaminants and fibre fragments can be accomplished by releasing the dust into the air, like by turning the material over, and then removing the dust-contaminated air. Release of dust into the air occurs whereever the raw material is rolled, beaten or thrown about. Accordingly the air at such positions is sucked away. Perforated drums, stationary perforated drums, stationary combs etc. are some instruments used to remove dust.


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Raw Material Used in Rotor Spinning:

Short staple spinning m/c (up to 60 mm fiber length) require

•  Cotton (CO)
•  Cotton waste ( secondary m/t recycled m/t)
•  Cotton noil
•  Blends of two or more of these materials.
•  Polyester fibers (PES).
•  Polyacrylonitrile fiber ( PAC)
•  Poly amide fiber (PA)
•  Viscose (CA)
•  Blends of man-made fibers ( mostly PES/ CV & PAC/CV)
•  Blends of cotton & man made fibers ( mostly CO/ PES & CO/CV)

Important Fiber Attributes in Rotor Spinning:

• Fiber strength
• Fiber fineness (optimum fiber fineness)
• Short fiber content
• Variation in fiber length
• Fiber to metal friction
• Residual trash and dust content

Raw Material Requirement:

Fiber Length:
Following m/t can be processed according to Reiter Company

Cotton:

•  Waste <7/8 inches ( for yarns up to 15 tex count)
•  Short-staple cotton < 1 inch ( for yarns up to 30 tex count )
•  Medium staple cotton < 1 1/8 inches (for yarn up to 17 tex count )

Man made fibers:-

•  Staple length up to 60 mm for count = 12 tex yarns

Fiber Fineness:
Finer fibers preferred in rotor spinning usually in the range of

•  Cotton 2.8 to 4.5 micronaire.
•  Man- made fibers 1, 1.2 to 1.7 dtex.

Coarse fibers lead to deterioration in spinning conditions; this necessitates the use of higher twist co-efficient.

Fiber Strength:
Due to poorer exploitation of the fiber substance, fibers of the greatest possible strength .

Dirt & Dust:
The rotor-spinning machine reacts very sensitively to the trash content of cotton. Coarse particles such as husk particles stay caught in the rotor groove. They can prevent yarn formation at this point, & this in turn can lead to an end down or to fiber agglomeration at the particle. This gives a thick place at the agglomeration point & immediately a thin place after this. More trash content also lead to more NEP generation. Small particles also lead to deterioration in quality.

Clean raw m/t is therefore a precondition for spinning of yarn on the rotor spinning m/c. in accordance with recommendations from Reiter, the following residual trash content should not be exceeded in the feed sliver:

•  Up to Ne 6 : 0.3%
•  Up to Ne20 : 0.2%
•  Up to Ne 30 : 0.15%
•  Up to Ne 50 : 0.10%

Other Foreign Matter:

•  Quartz & mineral dust present in cotton causes wear & tear in m/c
•  Foreign fibers lead to ends down.
•  Honey dew makes fiber to stick to m/c parts & cotton free of honey-due should be used.
•  Spin finish should be taken off before feeding to m/c. it acts same as honey due.
•  Remnants of the yarn lead to thick places in the yarn, so they should not be used. 

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Objects:

1.To know about gearing systems of the m/c.
2.To know production of speed frame.
3.To find out spindle speed.
4.To find out bobbin speed.

Main parts:

1.Motor
2.Motor pulley
3.M/C pulley
4.Main shaft
5.Fast wheel
6.Differential box
7.Last wheel
8.Draft change pinion
9.Twist change pinion
10.Rachet wheel
11.Gear wheel
12.Bevel gear
13.Top cone drum
14.Bottom cone drum

Specification:

Motor rpm = 960
Motor pulley dia = 5˝
M/C pulley dia = 7˝
Cradle wheel C = 40T
Cradle carrier wheel D = 44T
Spindle speed change wheel E = 55T
Differential motion spur wheel V = 19T
Jack wheel W = 36T
Bobbin shat chain wheel X = 32T
Bobbin shat wheel Y = 40T
Bobbin pinion Z = 22T
Swivel carrier wheel U = 51T
Differential motion carrier wheel T = 50T
Tender shaft wheel S = 40T
Tender wheel R = 68T
Bottom cone drum change wheel Q = 18T
Tender swivel bracket carrier wheel e = 36T
Top lifter change wheel f = 20T
Wheel on stud bevel g = 44T
Stud bevel wheel h = 22T
Double upright bevel wheel j = 22T
Double upright bevel wheel k = 18T
Reversing bevel l = 70T
Reversing bevel m = 70T
Bobbin lifter change pinion n = 14T
Socket swivel carrier wheel p = 72T
Socket stud wheel q = 13T
Lifter shaft wheel r = 57T
Lifter shaft pinion t = 18T
Lifter rack u
Spindle shaft driving sprocket F = 34T
End spindle shaft sprocket G = 32T
Spindle wheel I = 22T
Spindle shaft wheel H = 40T
Twist change wheel J = 30T
Twist carrier wheel K = 88T
Twist constant change wheel L = 28T
Front roller driving wheel M = 30T
First carrier wheel N = 62T
Second carrier wheel O = 40T
Large front roller wheel P = 81T
Front roller dia = 1˝
Top cone drum dia = 6.5˝
Bottom cone drum dia = 3.87˝ 

Calculation:
Conclusion: The gearing of Speed frame m/c is very complex. Moreover there are several change wheels and pinions, so proper attention and care is necessary during taking specification and doing calculation. From this practical we can asses about different speeds and productions of speed frame. I think this will help me in my future.

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Carding is the most important process in spinning. It contributes a lot to the yarn quality. The Carding efficiency is the mostly depend on optimum setting of the Licker-in to Cylinder, Cylinder to Flat and Cylinder to Doffer. 

Carding setting

1. The setting between cylinder and doffer is the closest setting in the card. This setting mainly depends upon the cylinder speed, hank of the delivered sliver and the type of wire. Cylinder speed up to 360, the setting should be 0.1mm. For cylinder speeds more than 450, the setting ranges from 0.125 to 0.15.

2. If the setting between cylinder and doffer is very close, the wires will get polished and this will affect the fiber transfer. If the setting is too wide, the fibers will not be transferred to doffer from the cylinder, hence cylinder will get loaded. While processing synthetic fibers cylinder loading will badly affect the yarn quality. Moreover, it is difficult to improve the wire condition if the loading is severe. The only solution would be to change the wire. Therefore enough care should be taken while processing synthetic fibres.

3. The most critical setting in a carding machine is between cylinder and flat tops. While processing cotton, it can be as close as 0.175 mm provided the mechanical accuracy of flat tops is good. Since most of the cards are with stationary flats at the licker-in side, the setting from the back to front for flats can be 0.25, 0.2.0.2, 0.2, 0.2mm.

4. Closer the setting between cylinder and flats, better the yarn quality. Neps are directly affected by this setting. Of course, very close setting increase the flat waste. For processing cotton the setting can be 0.25, 0.2, 0.2, 0.2, 0.2mm. For synthetic fibers it can be 0.3, 0.25, 0.25, 0.25, 0.25mm

5. Most of the cards are with 6 to 1 1 stationary flats at the licker-in side. This setting can start with 0.4 mm and end with 0.25mm.

6. The wire points can start with 140 ppsi and end with 320 ppsi. The work done by the first few stationary flats is very high; therefore the wear of these flats is also high. It would be better if the first 50% of the flats are changed after 100000 kgs of production and the rest after 150000 kgs of production.

7. These stationary flats open the material so that, the setting between cylinder and flats can be as close as possible.

8. The setting between feed plate and Licker-in depends upon the type of feed plate. Conventional feed plate setting is decided mainly by the feed weight and to some extent by the fiber length and type. With the latest feed plate and feed roller arrangements, the setting is decided mainly by the fiber length and to some extent by the feed weight.

9. Normally the setting between the feed plate and Lickr-in is around 0.45 to 0.7mm, depending upon the feed weight and fiber type.

10. The setting between Licker-in and the first mote knife is around 0.35 to 0.5 mm. This helps to remove the heavier trash particles and dust. Closer the setting, higher the wastage. The setting between Licker-in and combing segments is around 0.45 to 0.6. This helps to open the material.

11. Some cards have two mote knifes in the Licker-in under casing. The setting is around 0.4 to 0.5mm. This helps to remove the smaller trash and dust particles.

12. The setting between the cylinder and stationary flats at Doffer side helps to transfer the fibers to doffer by stripping the fibers to the top of the cylinder wire. This setting can be as close as 0.15mm. The number of wire points on stationary flats also plays a major role. It is normally around 300 to 400. For a high production application it can be as high as 600.

13. For cotton processing, the stationary flats are fixed with a knife attachment. The setting should be as close as possible, i.e. around 0.15mm. This helps to remove the trash particles of very small size.

14. The setting between cylinder and cylinder under casing should be as per the manufacturer's recommendation. The design of under casing is different for different manufacturers. This setting is very important, as wrong settings will affect the fiber transfer and can also create air turbulence.

Speeds:

1. Higher cylinder speed helps fiber transfer. Higher the production, higher should be the cylinder speed.
2. Higher cylinder speed improves carding action, thereby imperfections are reduced.
3. Higher Licker-in speed for coarse fibers and dirty cotton helps to remove the trash and improves,  the yarn quality. For fine and long cottons, higher speed results in fibre rupture, therefore, flat waste and comber noil will be more.
4. Higher flat speed, improves yarn quality and at the same time increases the flat waste.
5. With the same flat speed, higher the carding production, lower the flat waste and vice-versa.
6. Very high tension drafts will affect carding U%. It is better to keep the draft between feed rollers to doffer around 75 to 95. The results are found better with these drafts. 

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The rotor is the main spinning element of the rotor-spinning m/c. Yarn quality ,character working performance of yarn productivity, & costs etc. all depend chiefly on the rotor. The most important parameters of the rotor that exert influence are

•  The rotor form
•  The groove
•  The rotor diameter
•  Rotational speed along with
•  The rotor bearing
•  Co-efficient of friction b/w the fiber & the rotor wall.
•  The air-flow conditions inside the rotor
•  Liability to fouling

Rotors are replaceable element in the m/c.

Tasks of the Rotor Spinning Machine:
The basic tasks of the rotor spinning machine are

•  Opening (& attenuating) almost to individual fibers (fiber separation).
•  Cleaning.
•  Homogenizing through back doubling.
•  Combining i.e. forming a coherent linear strand from individual fibers.
•  Ordering (the fibers in the strand must have an orientation as far as possible in the longitudinal direction).
•  Improving evenness through back-doubling.
•  Imparting strength by twisting
•  Winding.

Principle of Rotor Spinning:
The general principle of rotor spinning is shown in Figure. The input fiber strand is a drawn sliver. A sliver may have more than 20,000 fibers in its cross-section. This means that a yarn of 100 fibers per cross-section will require a total draft of 200. This amount of draft is substantially higher than that of ring spinning. Drafting in rotor spinning is accomplished using a comber roll (mechanical draft) which opens the input sliver followed by an air stream (air draft). These two operations produce an amount of draft that is high enough to reduce the 20,000 fibers entering the comber roll down to few fibers (5-10 fibers). In order to produce a yarn of about 100 fibers per cross-section, the groups of few fibers emerging from the air duct are deposited on the internal wall of the rotor and a fiber ring is formed inside the rotor.

The total draft in rotor spinning is, therefore a combination of true draft from the feed roll to the rotor (in the order of thousands) and a condensation to accumulate the fiber groups into a fiber ring inside the rotor. The total draft ratio is the ratio between the delivery or the take-up speed and the feed roll speed. This should approximately amount to the ratio between the number of fibers in the sliver cross-section and the number of fibers in the yarn cross-section. 

Rotor Spinning process

Consolidation in rotor spinning is achieved by mechanical twisting. The torque generating the twist in the yarn is applied by the rotation of the rotor with respect to the point of the yarn contacting the rotor navel. The amount of twist (turns per inch) is determined by the ratio between the rotor speed (rpm) and the take up speed (inch/min). Every turn of the rotor produces a turn of twist, and a removal of a length of yarn of 1/tpi inches.

The winding operation in rotor spinning is completely separate from the drafting and the twisting operations. The only condition here is that the yarn is taken up at a constant rate. This separation between winding and twisting allows the formation of larger yarn packages than those in ring spinning.

Sequence of Operation:
The feed stock in form of either card sliver or draw frame sliver from first or second passage drawing. The sliver runs from a can beneath the spinning unit into the feed trumpet. A feed roller grips the sliver & pushes it over the feed through into the region of the opening roller. A spring ensures firm clamping of the sliver by urging the trough towards feed roller. In the event of an end-break, the feed unit is stopped either by stopping the feed roller rotation or by pivoting the in feed trumpet, in each case sliver feed stops automatically. The signal pulse causing this effect is generated by a yarn-sensing arm.

In the in conventional spinning processes, the fiber strand at in feed is maintained as a coherent structure & is merely attenuated during spinning. In rotor spinning, the fiber strand is opened to individual fibers. This task is performed mainly by the opening roller. This small roller which is clothed with needles or saw teeth, combs through the fiber beard projecting from the nip between the feed roller & the tough it transports the plucked fibers to the feed tube. An air flow is needed for further transport of the fibers to the rotor. This is generated by central fan that draws air by suction through leads from each rotor box. To facilitate generation of this under pressure, the rotor box must be hermetically sealed as far as possible. The suction stream in the feed tube lifts the fibers off the surface of the opening roller & leads them to the rotor. In the course of this movement, both the air & the fibers are accelerated because of the convergent form of the feed tubes. This represents a second draft following the nip trough/ opening roller & giving further separation of the fibers. Moreover partial straightening of the fibers is achieved in this air flow. A third draft arises upon arrival of the fibers on the wall of the rotor because the peripheral speed of the rotor is several times as the speed of the fiber. This is a very important feature because it contributes significantly to good orientation of the fibers. The last straightening of the fibers occurs as the fiber slides down the rotor wall into the groove under the influence of the enormous centrifugal forces work within the rotor.

Speed Interrelationship:
Normal & maximum revolutions & speeds are

•  Rpm of opening roller :5000 -10000 rpm
•  Rpm of rotor up to 100000 rpm
•  Delivery speed: up to 200m/min.

Technical Data of Rotor Spinning Machine:

•  Number of spinning positions per m/c           up to 220
•  Count range                                                12- 125 Tex (5 – 50 Ne)
•  Draft                                                           25- 400
•  Speed of rotation of opening roller               6000- 11000 rpm
•  Rotation speed of rotor                                up tp 120000 rpm
•  Rotor diameter                                            32 -65 mm
•  Delivery speed ( m/ min)                              up to 200
•  Package mass                                             up to 5 kg
•  Angle of taper                                             2° - 4° 20’
•  Winding angle                                             29° – 45°

Spindle:

The spindle is the main part of a ring frame which helps in twisting, winding simultaneously. Sometimes, spindle referred as ‘heart of spinning’. It hold the bobbin, somewhat loosely but tight enough to prevent slippage.

Functions of Spindle:

a) Twisting and winding is performed by spindle.
b) It holds the bobbin.
c) The capacity of ring frame is mainly determine by the number of spindle.

Different Parts of Spindle:

The parts of spindle are given below:-

1. Spindle blade
2. Wharve
3. Bolster
4. Lock
5. Bearing
6. Bolster cage

The last three parts help the spindle to fix at the right place and work properly. 

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The purpose of this research was to study the interaction between five principal factors known to influence rotor spinning of fine cotton yarns. The factors investigated were raw material, preparation, sliver weight, count, and twist. The study was set up as a factorial design with two replications. 

Rotor spinning process is fully different from carded or combed spinning. Rotor yarn is coarser than carded or combed yarn. The count of rotor yarn is very low. Most of rotor yarn count is below 20’s but highest yarn count may be 40’s .

The general effect of varying any one of these factors on rotor spinning is already well understood. By examining their interactions, however, it was deemed possible to acquire information on a number of other troublesome questions which are enumerated as follows:

1. Is combing beneficial generally, or only at fine counts, or only with long-staple cottons?

2. Is a long-staple cotton generally advantageous, or only at low twist?

3. When a low-micronaire cotton is used, under what conditions, if any, does the higher number of fibers in the yarn cross-section offset the tendency to form neps? Is the net effect of a fine cotton a function of yarn count?

4. To what extent is very high draft undesirable, i.e., should finer slivers be used in spinning fine yarns?

5. Are there high-order interactions, e.g., does fine yarn call for a long combed fiber with a low sliver weight?

6. Are the results of spinning performance consistent with those obtained by measuring yarn properties such as evenness, tenacity and appearance? 

Object:
1. To know about the different parts of the ring frame.
2. To know about the function of the different parts of the ring frame machine.
3. To know about the driving mechanism of the spindle
4. To calculate the front roller delivery of the machine
5. To study the machine in order to improve our technical knowledge.

Gearing Diagram Ring Frame:

Fig: Gearing diagram of ring frame

Machine specification:

• RPM of the motor = 1440
• Diameter of the motor pulley = 5″
• Diameter of the tin cylinder pulley = 10.5″
• Diameter of the tin cylinder = 10″
• Diameter of the wharve = 1.125″
• No of teeth of lower grip wheel = 26T
• No of teeth of upper grip wheel = 46T
• No of teeth of fibre wheel = 42T
• No of teeth of twist carrier wheel = 86T
• No of teeth of twist wheel = 48T
• No of teeth of front roller driving wheel = 98T
• Diameter of front roller = 1″

Calculation:

Result:
Spindle Speed = 6095.24 rpm
Front roller delivery = 323.56 inch/min

Conclusion:
Our teacher and lab assistants are very much helpful to us. Their well teaching and instruction help us greatly to understand this practical. I think this practical will be very helpful in my future career. 

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Balloon Size Depends On
1. Yarn count: Centrifugal force is acted during the operation of unwinding. If the yarn is coarse the stronger centrifugal force is produced during winding & hence larger balloon size is formed.

2. Yarn winding/unwinding rate: Higher the speed of winding/unwinding higher the centrifugal force is produced; hence larger balloon is formed.

3. Size of the package: If the package is larger for the same lift then the height of the balloon will be larger.

4. Lift of the package: Higher the lift of the package then the larger balloon is formed.

5. Position of the guide: If the yarn guide is placed at larger distance from the yarn package, then larger balloon is formed.

Anti-Ballooner
The anti-ballooner is made as a guide of special shape which is placed in the zone of the ballooning yarn motion.

Here 7 is one kind of anti ballooner

The principle of anti-ballooner is that the ballooning yarn periodically meets objects on its path, which disturbs the yarn balance in the balloon so that the latter acquires a more complicated multi-wave shape. At the moment the balloon shape changed, when the number of ballooning yarn wave changes, a shape decrease in yarn tension is observed.

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Traveller: 

Traveler is the most tinny and simple mechanical element in ring frame which carries the most important function like simultaneous twisting, winding, thread guide etc. We have discussed about features of Ring traveller in another article.

Ring traveller

A manufactured fiber in which the fiber-forming substance is any long chain synthetic polymer composed of at least 85% by weight of acrylonitrile units [-CH2-CH(CN)-] (FTC definition). Acrylic fibers are produced by two basic methods of spinning (extrusion), dry and wet. In the dry spinning method, material to be spun is dissolved is a solvent. After extrusion through the spinneret, the solvent is evaporated, producing continuous filaments which later may be cut into staple, if desired. In wet spinning, the spinning solution is extruded into a
liquid coagulating bath to form filaments, which are drawn, dried, and processed.

Acrylic fibers are synthetic fibers made from a polymer (polyacrylonitrile) with an average molecular weight of ~100,000, about 1900 monomer units. To be called acrylic in the U.S, the polymer must contain at least 85% acrylonitrile monomer. Typical comonomers are vinyl acetate or methyl acrylate. The Dupont Corporation created the first acrylic fibers in 1941 and trademarked them under the name "Orlon".

Acetylene + Hydrogen cyanide --> Acrilonitrile

2nd Method
Ethylene--Air Oxidation--> Ethylene oxide + HCN--> Ethylene cyanahydrin--Dehydration at 300 deg C (catalyst)--> Acrylonitrile

Production Process of Acrylic Fiber
The acrylic process is a "one step technology", with the following main characteristics:

1. polymerization in solution
2. direct feeding of the dope to spinning
3. wet spinning
4. DMF as solvent for both polymerization and spinning

Objects:
1. To know the necessary specification for calculation.
2. To know how to calculate the coils/inch of roving bobbin.

Theory:

M/c specification:
1. Rpm of motor pulley = 960
2. Motor pulley diameter = 5″
3. Machine pulley diameter = 7″
4. Cradle wheel = 40T
5. Cradle carrier wheel = 55 T
6. No of teeth in TCP = 28T
7. No of teeth in TCCP = 30T
8. Diameter of top cone drum = 6.5″
9. Diameter of bottom cone drum = 3.87″
10. Bottom cone drum change wheel = 18T
11. No of teeth of fender wheel = 68T
12. No of teeth of fender shaft wheel = 30T
13. Fender swivel bracket carrier wheel = 36T
14. Top lifter change wheel = 18T
15. Wheel on stud bevel = 44T
16. Stud bevel wheel = 22T
17. Double upright bevel wheel = 22T
18. Double upright bevel wheel = 18T
19. Reversing bevel = 70T
20. Reversing bevel = 70T
21. Bobbin lifter change pinion = 16T
22. Socket swivel carrier wheel = 72T
23. Socket stud wheel = 13T
24. Differential motion carrier wheel = 57T

Fig: Gearing diagram of Roving Frame to calculate no of coils per inch of the roving bobbin

Calculation:
We know, Bobbin speed = 822
Spindle speed = 749
Therefore, Coils per minute = 822 – 749
                                          = 73
Result:
No. of coils per inch = 11.

Conclusion: 

Our teacher and lab assistants are very much helpful to us. Their well teaching and instruction help us greatly to understand this practical. I think this practical will be very helpful in my future career.


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