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Rings in Ring Spinning System - How it works?

The Form Of The Ring:
Basic Forms: These are classified into:

Lubricated rings (in woollen and worsted spinning),
Unlubricated rings.
The standard ring of the short staple spinning mill the unlubricated type, can be considered under the headings:
- Single sided rings,
- Double sided rings.
For rings used in the short — staple spinning mill two dimensions are of prime importance; the internal diameter and the flange width.
 

The anti – wedge ring:
This was the first high performance ring. Compared with the previouslystandard ring form, it exhibits on enlarged flange inner side and is markedly flattened on its upper surface. This change of form permitted use of travelers with a lower center of gravity and precisely adapted bow (elliptical travelers), which in turn allowed operation at higher speeds. Anti  wedge rings and elliptical travelers belong together and can be used only in combination.

The low crown ring (conventional ring):
In the low crown ring, the curvature of the surface has been somewhat flattened compared with rings used up to that time. This gives more space for the passage of the yarn so that the curvature of the traveler can also be reduced (oval, flat travelers) and the center of gravity is lowered. In comparison with the anti wedge ring, the low  crown ring has the  advantages that the space provided for passage of the yarn is larger and that all current traveler shapes can be applied with the exception of the elliptical traveler. Today it is the most widely used ring form.

SU ring:
It has two advantages, namely a large surface of contact for the traveler on the inner flange (with correspondingly good heat transfer to the ring) and a degree of compensation of forces acting on the traveler. SU rings with corresponding travelers permit higher traveler speeds, especially with synthetic fibers and give a slight reduction in traveler wear.

Materials for the ring:
The ring should always be tough and hard on its exterior. The running surface in particular deserves the closest attention. The surface layer must have high and even hardness. The traveler hardness should be lower so that wear occurs mainly on the travelers, which is easier to replace and cheaper. Surface smoothness is also important. The following materials are used:
- Flame, or induction, hardened steel, to some extent,
- Nitrided steel,
- Carbo — nitrided steel (this is the most common)
- Chrome steel (this is found more rarely).
A good ring should have the following features:
1. Best quality raw material,
2. Good, but not too high, surface smoothness,
3. Exact roundness,
4. Good, even surface hardness, higher than that of the traveler,
5. It should have been run in as well as possible
6. Long operating lifetime,
7. Correct relationship between ring and bobbin diameter (2:1 up to 2,2:1),
8. It should be exactly centered relative to the spindle.
THE TRAVELLER

Task and Function:
The traveler imparts twist to the yarn, and enables winding of the yarn on the cop. The speed difference is due to lagging of the traveler relative to the spindle.
The traveler does not have a drive of its own but is dragged along behind the spindle.
High contact pressure (up to 35 cN/mm²) is generated between the ring and the traveler during winding, mainly due to centrifugal forces. The pressure induces strong frictional forces which in turn lead to significant generation of heat. This is the main problem. The low mass of the traveler does not permit dissipation of the generated heat in the short time available. As result, the operating speed of the traveler is limited.
Traveler Classification
Travelers are required to wind up yarns of very different types:
1. Coarse/fine;
2. Smooth/hairy;
3. Compact/voluminous;
4. Strong/weak;
5. Natural fiber/man made fibers.
These widely varying yarn types can not all be spun using just one traveler type is needed. Differences are found in: form, mass, raw material, finishing treatments of the material, wire profile, size of the yarn clearance opening for the thread.
The Form Of Traveller
The traveler must be shaped to correspond exactly with the ring in the contact surface, with the greatest possible surface area, is created between these two elements. The bow should be as flat as possible, in order to keep the center of gravity low and improve smoothness of running. These two features have a significant influence on the achievable traveler speed.


The flat bow must still leave adequate space for passage of the yarn. If the yarn clearance opening is too small, rubbing of the yarn on the ring leads to roughening of the yarn, a high level of fiber loss as fly, deterioration of yarn quality and formation of melt spots in spinning of synthetic fiber yarns

The Wire Profile Of The Traveller
Wire profile also influences both the behavior of traveler and certain yarn characteristics,
- Contact surface of the ring,
- Smooth running,
- Thermal transfer,
- Yarn clearance opening,
- Roughening effect,
- Hairiness.

In the figure wire profiles and average yarn clearance as a function of the traveler wire cross sections are given.
The Material Of The Traveller
The traveller should be:
1. Generate as little heat as possible.
2. Quickly distribute the generated heat from the area where it develops
over the whole volume of the traveller.
3. Transfer heat rapidly to the ring and the air.
4. Be elastic, so that the traveller will not break as it is pushed on the rings.
5. Exhibits high wear resistance.
6. Be somewhat less hard than the ring, because the traveller must wear away in use in preference to the ring.
In view of these requirements, travelers used in short staple spinning mill are almost exclusively made of steel. However, pure steel does not optimally fulfill the first three requirements. Accordingly, traveller manufacturers have made efforts over several decades to improve running properties by surface treatment. Suitable processes for this
purpose are:
*Electroplating, in which the traveller receives a coating of one or more metallic layers, (nickel and silver)
*Chemical treatment of the surface to reduce friction and pitting.
The Traveller Mass
The traveller mass determines the magnitude of frictional forces between the traveller and the ring, and these in turn determine the winding and the balloon tension. If the traveller is too small, the balloon will be too big and the cop too soft; material take-up in the cop will be low. An unduly high traveller mass leads to high yarn tension and many end breaks.
Accordingly, the mass of the traveller must be matched exactly to both yarn and the spindle speed. If a choice is available between two traveller weights, then the heavier is normally selected, since it will give greater cop weight, smoother running of the traveller and between transfer of heat out of the traveller.

The Traveller Clearer
Yarn consist of fibers that are bound into structure more or less effectively, but that are in any event relatively short. The yarn runs through the traveller, some fibers will be detached. For the most part they float away into the atmosphere, but some remain caught on the traveller. These retained fibers can accumulate until they form a tuft, and the resulting increase in traveller mass can lead to much increased yarn tension which finally can induce an end break.
Traveller clearers are mounted close to the ring in order to prevent formation of such fiber accumulations. They should be set as close as possible to the traveller without interfering with its movements. Exact setting is vitally important.

THE MACHINE DRIVE
About 20 % of production costs in spinning mill (tex 20) fall under the heading energy and of these costs about two thirds are used in the ring spinning section.
In a ring spinning mill with 25000 spindles and an operating time of 7000 hours per year, a saving of 10% on an annual power bill of 1 million dollars will bring very interesting financial returns.
Power supplied to the ring spinning machine is absorbed by:

- the spindle (including the travelers)	65 – 70%
- the drafting arrangements	25%
- the ring rail	5 – 10%

The Structure of The Cop
The cop is the characteristic form of package by the ring spinning machine. It has three clearly  distinguishable parts.
The lower curved base (A), the middle, cylindrical part (Z) and the conical part (S).
The Winding Process
If the point of lay of the yarn on the tube is constantly moved upwards, a cop structure could be occurred. There are two ways of achieving this; a gradual rise of the ring rail can be joint on the continual up and down movement or the spindle rail can be gradually lowered.
Ring frames produced today are exclusively of the moving rail type. The ring rail has to perform two movement in order to lay one main and one cross winding, gradual raising in small steps after each layer movement in order to fill the cop.

The Builder Motion
Owing to the rotation of the eccentric, the lever and the chain drum are continually raised and lowered. This movement is transferred to the ring rail by way of the discs (a and b) together with the chain and belt, thus giving the traverse movement.
Each time the lever moves down, it presses the catch to release the ratchet wheel (A), which a slight rotation of the drum (T) connected to the ratchet wheel.
A short length of chain (K) is thus wound up on the drum. This leads to rotation of the disc (a), shaft (W) and disc (b), and finally to a slight rise in position of the ring rail (R). The shaft (W) also carries a third disc (c) from which the balloon control rings (B) and lappets (F) are suspended by belts.
These are correspondingly raised and lowered but since disc (c) is slightly smaller than disc (b), the stroke length is somewhat shorter.

Building The Base
Raising and lowering of the ring rail (R) comes about because the eccentric (E) moves the lever (H) up and down and thus the disc (a) is continually turned alternately to the left and the right. Disc (a) carries the cam (N), which projects beyond the periphery the disc and thus forms a lobe of larger diameter than the rest of the disc.

At the start of winding of a cop, disc (a) is located in the position, in which the lobe noticeably deflects the chain (K). The effect of this deflection is that the chain elongation upon raising of the level (H) is not wholly transferred to the ring rail. Some part is lost as deflection at N. The traverse stroke of the ring rail no longer corresponds to the setting. It is shorter. Since the length of yarn delivered during each traverse stroke is the same, the volume per layer is increased thereby generating the curvature.

Disc (a) turns to the right in the same small steps and the cam is carried out of line with the chain. Finally the complete elongation of the chain is passed on to the ring rail and the cop takes up its normal build.

Automatic Doffing in Ring Spinning

Doffing
Although it takes between 2 and 4 hours to fill a cop depending upon yarn fineness, process limitations restrict weight of the yarn on the cop to the range 50 – 140 g. Therefore adding an additional processing stage is unavoidable after spinning. In case of hand doffing, this thread reverse is formed on the tube, and in the case of automatic doffing on the spindle.

The reverse is needed so when the cop is doffed the yarn is still held on the spindle. Otherwise, a tread break would occur. In modern machines doffing is carried out automatically.
Manuel doffing:
Manuel doffing is un attractive work. It comprises only very few manipulations which have to be performed very quickly and must be continually repeated. Furthermore, the work usually has to be carried out in the bent posture.

Automatically doffing:

A distinction is drawn between two groups of so called auto doffers; Stationary equipment that forms an integral part of the ring spinning machine itself. Travelling carriages that can serve several machines. In most cases a stationary installation comprises essentially the following parts; A conveyor belt that runs past all spindles on one machine side and carries pegs to receive empty tubes and full cops.

A doffing beam also extending over the full length of the machine side and fitted with nipples insertable into the tubes.
A lifting mechanism, usually in the form of a scissors mechanism, for raising and lowering the beam and also for swinging it in and out. A tube preparing and donning device at one end of the machine. A cop receiving unit at the same end of the machine.
During the whole of the cop winding operation the doffer stays in its rest position. When the cops have been filled the lifting rods swinging out the beam while simultaneously raising it. When the uppermost position of the beam has been reached, the rods swing the beam in so that the beam moves over the cops and is then lowered until the nipples engage within the cop support tubes. Once the cops have been grasped the beam is raised, thus lifting the cops off the spindles. The rods swing out, lower the beam and move it over the conveyor. The cops are then seated on the belt.
Thereafter the pressure air is vented and the cops are released.

The Possibilities for Automation in Ring Spinning

The following operations associated with the ring spinning machine can be considered for automation.

• Transport of roving bobbins to the ring frame: This would be a very useful step. Installations enabling this are becoming available.
• Exchange of roving bobbins in the creel of the ring spinning machine: This would also be useful step but raises difficult problems; the first installations for the purpose are also now becoming available.
• Threading rovings and piecing roving breaks: It is difficult to design appropriate automatic devices and the operation itself does not arise very frequently. Benefits would be inadequate in relation to costs.
• Take up and removal of waste: This has been put into practice already in thread break aspirators.
• Piecing end breaks: This is desirable but involves complex solutions which still can not bring 100% piecing success. At present the cost/benefit ratio is often unfavorable.
• Stopping roving feed when an end breaks: The devices currently available tend to be complex.
• Doffing: Doffing has been solved satisfactorily and is already normal practice.
• Cleaning: Cleaning has been largely solved by use of traveling cleaners.
• Although quality of performance is not fully satisfactory.
• Repair and maintenance: Effort involved has been reduced in comparison with the past but much still has to be performed manually.
• Transport of cops to the winder: It represents the next major step in automating the ring frame.
• Machine monitoring.
• Production monitoring
• Quality monitoring: This probably can not be achieved directly because of the large number of individual producing units. Recently clearing systems solve this problem while the spinning processes continuous.

The Equipment of The Ring Spinning Frame

• End break aspirators,
• piecing devices
• cleaning devices,
• roving stop devices,
• travelling cleaner,
• monitoring,
• automatic cop transport.

End break aspirators
End break aspirators removes fibers delivered by the drafting arrangements after an end break and thus prevents a series of end breaks on neighboring spindles. At another level, it enables better environmental control, since large part of the return air — flow of the air conditioning system is led past he drafting arrangement, especially the region of the spinning triangle. Today, 50% of the air conditioning plant via the end break aspirators.
Piecing devices
Fitting each spinning position with its own piecing device would be too expensive. Travelling piecing carriages are provided on rails fitted to the machine. The piecing carriages has to perform mechanically the same rather complicated operations as the operative performs manually.
The complete process is carried out as follows: During patrolling movement along the ring spinning machine, each individual position for an end down. If a yarn is present, the patrol is continued and the next position is checked. If a broken end is detected, the device stops in front of the spindle, swings out a frame carrying the operating elements and centers it further operating unit is lowered onto the ring rail and follows its movements during the subsequent operations.
The broken end is blown from the cop upwards into the trumpet – shaded opening of a suction tube; prior to this step, the broken end may be located anywhere on the wound circumference of the cop. A hook grasps the yarn between the top of the tube and the thread guide, in the same way as the operative’s hand in manual piecing. This hook lays the yarn on the ring, and the piecing arm joints the yarn to the fiber strand at the front rollers of the drafting arrangements. The superfluous yarn section is severed and sucked away. The success of the operating is monitored by a photocell. If necessary, the joining operation is repeated once or twice.
If a thread breaks on the ring frame, the fiber strand continues to run from the drafting arrangement, usually into the aspirator. The strand licks around a roller and forms a lap. This can damage top rollers and aprons, deform bottom rollers, and cause ends down on neighboring spindles. Removal of a lap is complicated and troublesome. It would therefore be desirable to interrupt the flow of fibers from the time an end break occurs until piecing is carried out. The roving must be automatically threaded into the drafting arrangements. Roving stop motions can be provided as part of a travelling device or as assemblies at each individual spinning positions.

The complete process is describes as follows:
The optical monitor checks the running yarn. In the event of an end break, the optical unit (1) and the electronic unit (2) cause the wedge (3) to interrupt roving feed. The feed table, and possibly twist spin pins (4), hold the roving securely in the break draft field.
After the broken end has been made ready, wedge (3) is retracted manually by means of the roving blocking device (5). Roving is delivered again and piecing can be carried out.
Travelling cleaners
On the ring frame, most fly and dust (up to 85%) is released in spinning triangle and the main drafting field. The remainder is set free mainly at the balloon and traveller.
Cleaning devices can be typed as follows:
· Stirrers,
· Blowing down devices,
· Suction devices,
· Combined blowing and suction devices.
Stirrers
There are simple fans with short blowing nozzles, driven by a small electric motor and running on power supply rails above the machines.

Blowing / suction devices

The most widely used form of device today works in the same way as the stirrer, although with much greater power input.
The device also has several hoses which hang down the ground. One or two of these hoses per side work as blowers and the other sucks up material which has been blown down onto the floor.
Where suction devices are in use, a filter and a filter cleaning device also required.

Automatic Cop Transport

Batches of material should flow along the shortest possible paths in time with the rhythm of production and from one production position always to the corresponding next position in the line. This description can hardly be applied to a spinning mill. Current mill production has three serious disadvantages:

• High expenditure on transport,
• Long material through flow times,
• Intermediate storage of a great deal of material.

Equipment enabling automatic transport between the ring frame and the winder can be considered under two headings:
- intermediate transport,
- direct link.
Intermediate transport
In this system, an automatic transport installation is provided between the ring spinning room and he winding room. At the ring spinning machine, the transport device takes up cop boxes coded according to their contents and brings them to a distribution station controlled by microprocessors. This station directs the boxes to their intended destination. The empty tubes are deposited in other boxes and returned via a second conveyor system to the ring spinning room.
Intermediate transport systems are very flexible; they enable operation will small lots, they are rapidly adaptable.
They can be rather complex, costly and liable to faults, also the conveyor equipment can form obstacles.

Direct link
Two machines, ring spinning frame and winder, can be linked to form a production unit. In an installation of this type the cops doffed at the ring frame are passed via the shortest path to the winding machine. Transfer speed is slow, corresponding to the operating speed of the winding units. Empty tubes are returned to the loading station of the autodoffer at the ring spinning machine. Directly linked systems are therefore optimal when they can be applied as far as possible to production of only one yarn count.

Classification of Vortex Yarn structure

Some typical fiber configurations in vortex yarns are given in Figure 3-6. As seen from figures vortex yarn structure varies along the yarn length. The configuration of each tracer fiber was studied and grouped according to the classification illustrated in Table 3. Results of fiber configuration classification showed that the percentage of straight, hooked(trailing) and hooked(both ends) is very close to each other.






Migration in Vortex Yarn
The images captured during analysis of yarn structure suggest that the fiber migration in vortex yarns differs from that in both air jet and ring yarns. A close look to the twist insertion mechanisms in these spinning technologies reveals the reason behind this discrepancy. In ring spinning, twist is inserted a thin ribbon shape fiber bundle coming from the front roller of drafting device by the traveler. As fibers are transformed to roughly circular shape most of them are grasped at the nip of the front rollers and in already formed yarn structure. During yarn formation fibers on the edges are subjected to the tension and fibers in the core are subjected to “compression”. The edge fibers try to lessen the stress by migrating to the inner layer while the core fibers are displaced to the outer layers and these now become edge fibers. This process of fiber movement in the cross section (migration) is repeated. As a result fibers leave their helical path and give an interlocking structure. This structure includes fibers migrate periodically, going inward from the surface into the center of the yarn and then back out, with some random fashion[10]. In air jet spinning, fibers leaving the front roller of the draft zone advance to the two contra-rotating nozzles. The second nozzle imparts a false twist to the fiber strand that migrates back to the front roller. The first nozzle, which has lower intensity than the second one prevents edge fibers from receiving false twist. Therefore as the fiber strand enters the second nozzle only core fibers have full twist; edge fibers either do not have any twist or have twist in opposing direction. When the fiber strand leaves the nozzle core fibers become untwisted and edge fibers receives twist and wrap around the core fibers. The resultant yarn has a central core of mostly parallel fibers wrapped with wrapper fibers[12,15]. In air jet spinning the great majority of the wrapping fibers are
leading-end fibers since the control of aprons prevents a trailing end from becoming an effective and long free end [5]. Unlike ring yarn structure, in air jet yarn the “migration” does not repeat. Although vortex spinning can be considered as the modification of air jet spinning there are key differences between the principles of yarn formation in these spinning technologies. In vortex spinning fibers emerging from the front rollers are sucked into the spiral orifice at the inlet of the air jet nozzle and move towards the tip of the needle protruding from the orifice. In the meantime, these fibers are subjected to whirling air flow and receive twist. Twist tends to move upwards, but the needle prevents this upward twist penetration. Therefore, the upper parts of some fibers are kept open as they depart from the nip line of front rollers. After these fibers have passed through the orifice, the upper parts of the fibers spread out due to the whirling air flow and wind over the hollow spindle. Subsequently these fibers are wrapped around the fiber core and turned into yarn as the already formed yarn part is pulled trough the spindle [4,14,17]. The main difference between the air jet and vortex yarn is the number of wrapper fibers which is much higher in vortex yarns. In air jet spinning only the edge fibers (fibers lying at the edges of the ribbon like fiber bundle as it leaves the front roller) become the wrapper fibers. In vortex spinning, on the other hand, the fiber separation from the bundle occurs everywhere in the entire outer periphery of the bundle. It is very likely that during yarn formation the leading part of fibers will not be able to escape from the false twist penetrating upwards and eventually located in the core. The trailing parts, on the other hand, won’t receive twist and become wrapper. The images captured during analysis of yarn structure confirmed this assumption. Most of tracer fibers first showed core fiber
Structure and Properties of Vortex Yarns
Yarn Properties
Statistical analysis of the data from yarn testing showed that in 50/50 polyester/cotton blended yarn the shorter front roller to the spindle distance gave lower irregularity, imperfection and hairiness values. The imperfection values also were low but hairiness was high at the low nozzle angle and large spindle diameter. The high nozzle pressure produced less hairy yarns. The yarn speed affected yarn evenness, hairiness and the number of thick places. The low yarn speed resulted in more regular yarns with fewer thick places and low hair. The interaction of the front roller to the spindle distance and the spindle diameter had a significant effect on elongation and the number of thick places. When the front roller to the spindle distance was short the smaller spindle diameter resulted in the higher elongation; on the other hand when the front roller to the spindle distance was large the large spindle diameter produced the higher elongation. The tenacity values were affected by the interaction of the spindle diameter and nozzle angle. While at the high nozzle angle, the large spindle diameter caused higher tenacity at the low nozzle angle it was opposite. The interaction of the nozzle pressure and nozzle angle, and the interaction of the spindle diameter and nozzle angle had a significant effect on hairiness. The combination of the high nozzle pressure and angle, and the combination of the small spindle diameter and high nozzle angle produced yarns with less hair.
Like 50/50 polyester/cotton blend yarns, in 100% cotton yarns the short front roller to the spindle distance produced more even yarns with fewer imperfections and less
hair. The nozzle angle had a significant effect on evenness and hairiness values. The high nozzle angle caused more even and less hairy yarns. The interaction of the high nozzle angle and short front roller to spindle distance led to improved evenness. Nozzle pressure and spindle diameter only affected hairiness. Hairiness was low at the high nozzle pressure and the small spindle diameter. The yarn speed had a significant effect on the number of thick places and hairiness. A low yarn delivery speed caused fewer number of thick places and low hairiness. The interaction of the yarn speed and nozzle angle had a significant effect on hairiness as well.
In vortex spinning fibers coming from the front rollers are first sucked into the spiral orifice at the entrance of an air jet nozzle by the air jet stream. Following the air jet nozzle the fiber bundle enters a hollow spindle. The false twist insertion starts at the inlet of the spindle. Twist tends to propagate towards the front rollers, but this penetration is prevented by the needle protruding from the orifice. Therefore the upper portions of some fibers are kept open as fibers move towards the spindle. When the fiber bundle leaves the orifice the upper portion of the fibers begin to expand and wind over the spindle. These fibers are whirled around the core and form into MVS yarn as they are drawn into the hollow spindle (See section 2.3.2)[14]. The distance between the front roller and the spindle is critical since it determines the number of wrapping fibers. If this distance shorter both ends of fibers are tightly assembled resulting in fewer open ended fibers, in turn, a yarn consisting of mostly parallel core fibers held with fewer wrapper fibers as in the case of air jet yarn. In the mean time yarn evenness and imperfections are better since there is less chance to lose control of fibers during the bundling of the parallel core fibers which forms the main part of the yarn with a few wrapper fibers. Waste is less because
of better fiber control as well. The yarn has less hairiness and a leaner appearance. If this distance is longer the number of wrapper fibers increases, but also less fiber control is present. The resultant yarn is softer due to increasing wrapper fibers and has more hairiness with longer hair. The waste fiber rate, however, is higher compared to that in short setting [16].
When nozzle pressure increases, both the axial and the tangential velocity increase. As a result the fiber bundle receives more twist and yarn becomes stronger but stiffer. The nozzle angle plays critical role on characteristic of the air flow as well. A high nozzle angle causes higher tangential velocity, in turn, higher twist. Surprisingly results showed that neither the nozzle angle and nor the nozzle air pressure had any effects on yarn tenacity and elongation. Another surprising result was in 100% cotton yarn, the high nozzle angle caused better evenness, which was the opposite of what would be expected. A lower nozzle angle should result in better yarn evenness due to the increasing axial velocity of air flow. Probably the levels used in this study were too close to show the real effect of these parameters. Hairiness values, on the other hand, were low at high nozzle angle and high air pressure supporting that twist increases as nozzle angle and pressure go up, and fibers are integrated more tightly into the yarn structure.
Spindle diameter determines the tightness of the wrappings [16]. A small spindle diameter gives less freedom to the fiber bundle to expand as it enters the spindle. This generates higher friction between fibers and results in tighter wrappings, higher twist and in turn denser yarns with less hair. With a large spindle diameter the fiber bundle has more freedom to move inside the spindle and therefore some twist is lost, wrappings
become looser and yarn becomes bulky and more hairy. Results supported that a small spindle diameter resulted in low hairiness.
Yarn Structure
Results from 434 individual tracer fibers were obtained through the computer analysis. Statistical analysis of results showed that none of the process parameters had any significant effects on the mean fiber position, r.m.s. deviation, helix angle or helix diameter. Mean migration intensity and equivalent migration frequency, on the other hand, were influenced by yarn speed and nozzle angle. Both were high at the low yarn speed and high nozzle angle. The possible reason for this at low speed the movement of fiber bundle inside the nozzle chamber is slower so that the fibers in the bundle are subjected to whirling air current at a longer period of time, and at high nozzle angle twist increases due to rising tangential velocity and this might cause an increase in the values of the mean migration intensity and equivalent migration frequency. The nozzle pressure and the interaction of nozzle pressure, speed and front roller to spindle distance also had a significant effect on the mean migration intensity. The mean migration intensity was high at the high nozzle pressure. The interaction of the high nozzle pressure, low yarn speed and short front roller to spindle distance gave the highest mean migration intensity values. Yarn diameter was mainly affected by yarn speed. It was smaller at the low delivery speed. Again this can be attributed to the fiber bundle being exposed to the whirling air force for a longer period time at the low yarn speed.

Vortex Spinning System

The vortex spinning technology is one of the most promising new inventions in the spinning market. This relatively new spinning system was also developed by the Japanese firm Murata (Muratec). Murata’s No. 851 Vortex Spinner made its first appearance at OTEMAS’97 [34]. Vortex spinning is a false twist process, and the twist insertion in this system is achieved by means of air jets.  The main attraction of vortex spinning is that it is claimed to be capable of spinning 100% carded cotton fibers at very high speeds (400m/min),

and the resulting yarn structure is more similar to ring yarn than to rotor yarn [4,9,13,15,53]. Figure 7 shows vortex yarn versus rotor and ring yarns. Other claimed advantages of vortex spinning are a low maintenance cost due to fewer moving parts, elimination of the roving frame stage, and improved fully automatic piecing system [48]. In addition to these, yarns produced by this method have low hairiness compared to normal ring yarns. This is claimed to be due to being “air-singed” and “air-combed,” which in turn results in reduced fabric pilling; and fabrics made from vortex yarns have outstanding abrasion resistance, moisture absorption, color-fastness and fast drying characteristics [4]. Murata suggests that MVS is best suited by far to the high volume production of medium cotton yarns from carded cotton. Thus, it seems that this spinning system presents more of a threat to rotor spinning.

One of the major setbacks of this spinning technology is the high speed drafting. In this system the drafting unit has to operate at a speed 10 times higher than in the case of ring spinning [28,65]. Other major problems are the fiber loss during spinning and the frequent contamination in the jet nozzles since fiber material may be fed to the spinning unit without being adequately cleaned (by combing for example)[9].
Principle of Vortex Spinning
In the MVS system a sliver is fed directly to a 4-line drafting unit. Figure 8 shows a MVS spinning unit. When the fibers leave the front roller of the drafting device, they are drawn into a fiber bundle passage by air suction created by the nozzle. The fiber bundle passage consists of a nozzle block and a needle holder. The needle holder has a substantially central, longitudinal axis and a guide surface that twists relative to the longitudinal axis (Figure 9.) A pin-like guide member associated with the needle holder protrudes toward the inlet of the spindle (Figure 10) [64].

Following the fiber passage, fibers are smoothly sucked into a hollow spindle. Twist insertion starts as the fiber bundle receives the force of the compressed air at the inlet of the spindle. The twisting motion tends to propagate from the spindle toward the front rollers. This propagation is prevented by the guide member which temporarily plays a role as the center fiber bundle. After fibers have left the guide member, the whirling force of the air jet separates fibers from the bundle. Since the leading ends of all fibers are moved forward around the guide member and drawn into the spindle by the preceding portion of fiber bundle being formed into a yarn, they present partial twist and are less affected by the air flow inside the spindle. On the other hand, when the trailing ends of the fibers which have left the front rollers move to a position where they receive the powerfully whirling force of the nozzle, they are separated from the fiber bundle, extend outwardly and twine over the spindle. Subsequently, these fibers are spirally wound
around the fiber core and formed into a vortex spun yarn as they are drawn into the spindle (Figure 11 and 12) [15,64].

Figure 9. (a) plan view, (b) front view, (c) side view, and (d) perspective view of the needle holder [64]

Figure 10. Needle holder with the guide member [64]

Figure 11. Principle of Vortex Spinning [64]
The finished yarn is wound on a package after its defects have been removed. During the yarn formation, as the twist propagation is prevented by the guide member, most of the fibers do not receive the false twist. Besides, the fiber separation from the bundle occurs everywhere in the entire outer periphery of the bundle. This results in a higher number of wrapper fibers in the yarn. That’s why vortex spun yarns present much more wrapper fibers than air jet spun yarns, and their yarn structure is similar to ring yarns [15,49,64]. Figure 13 represents an idealized structure of vortex spun yarn.

Figure 12. Yarn formation in vortex spinning [15]

Figure 13. Idealized structure of MVS yarn [15]

Vortex spg Vs Airjet Spinning

Vortex spinning can be viewed as a refinement of jet spinning or a natural development in the fasciated yarn technology. Like in all other fasciated yarns, the structure of vortex yarn consists of a core of parallel fibers held together by wrapper fibers. This has been revealed by examining an untwisted yarn sample under the Scanning Electron Microscope. Subsequently the physical properties of vortex and air jet yarns produced from different polyester cotton blends were compared. Results indicated that vortex yarns have tenacity advantages over air jet yarns particularly at high cotton contents.

3.0 Introduction
The yarn structure is one of the primary factors which control the properties of spun yarns. Vortex spun yarn has a two part structure. This can be simply revealed by untwisting a vortex yarn by hand. Because the yarn is a relatively small component a more reliable conclusion requires visual help. As a first step of this study a piece of vortex yarn was untwisted and viewed under the Scanning Electron Microscope. Since none of the conventional twist measurement methods are suitable for vortex spun yarns, untwisting was performed with the aid of an optical microscope, and the completion of untwisting was visually confirmed. SEM pictures agreed that vortex yarns consist of two distinctive parts: core and sheath. In the pictures the sheath part appeared looser due to removed twist (Figure 1).
Only limited information was obtained through SEM pictures. In order to broaden our knowledge about this new and fascinating yarn technology the next logical step was to compare the properties of airjet and vortex yarns. Although both systems are used to spin fasciated yarns, no work has been reported to date regarding the difference between these yarns. A study was conducted to reveal the difference between the properties and structure of the vortex and air jet spun yarns. In the first part of this study the properties of vortex and airjet spun yarns made from various PES/Cotton blends were compared. In the second part, vortex and air jet yarns produced from three different blends of cotton and black polyester fibers were visually examined under an optical microscope.

Materials and Methods
For the first part of the study, five different blend ratios: 83/17, 67/33, 50/50, 33/67, and 17/83 were obtained from polyester and carded cotton slivers by blending them on the draw frame. Table 1 shows the properties of cotton and polyester fibers used
in this study. After three passages of drawing, slivers were transferred to MJS and MVS machines. Table 2 displays the process parameters used on MJS and MVS systems.


The spinning of pure cotton and the polyester/cotton blend with 83 % of cotton ratio was not possible for MJS system. In fact, when the blend ratio of polyester was less than 50%, it was very difficult to spin yarn with an acceptable end break level on this system. MVS system successfully produced yarns from 100% polyester and polyester/cotton blends, but spinning 100% cotton was not successful. One possible reason is the high short fiber content of cotton slivers.
The quality parameters of the produced yarns were evaluated on Uster Evenness Tester, Uster Tensorapid (Testing speed 250 mm/m) and Uster Tensojet (Testing speed 400m/m).
In the second part of the study, in order to compare the basic structure of vortex and air jet yarns, blended yarns were produced from three different blends of black polyester (1.7 den, 1.5 in) and cotton fibers (4.1 mic., 0.91 in) (blend ratios: 33/67, 50/50, 67/33). These yarns were examined under an optical microscope to find out any possible tendencies of cotton or polyester fibers to become either wrapper or core fibers in blended yarns. Besides the visual examination of yarn structure, the evenness and tensile properties of these yarns were tested on the Uster Evenness Tester and Uster Tensorapid, respectively.
Results and Discussion
An analysis of variance (ANOVA) was performed to determine the statistical significance of any observed differences between the properties of vortex and airjet spun yarns. The ANOVA revealed that yarns made by the MVS had superior evenness, fewer number of thick places and lower hairiness values compared to those made by the MJS (Figure 2 and Table 3). Vortex yarns also presented higher tenacity values for every blend ratio except the 100% polyester case, and as the cotton content increased in the blend, the difference enlarged (Figure 3 and Table 4). For 100% polyester yarn, on the other hand, the tenacity values of vortex and airjet yarns did not differ significantly. In the case of yarn elongation the outcome was the opposite. Vortex yarns exhibited lower elongation values compared to airjet yarns. Unsurprisingly, this led to an insignificant difference in their work of rupture values.
The unique yarn structures associated with these yarns are a possible reason for the difference in yarn quality parameters. The higher tenacity values of vortex yarns can be attributed to the higher number of wrapper fibers in these yarns. The number of wrapper fibers is critical to yarn strength since they hold the internal parallel fiber bundle tightly together. In air jet spinning edge fibers ultimately produce wrapper fibers, and the number of edge fibers depends on the fibers at the outside [1,2]. On the other hand, in vortex spinning the fiber separation from the bundle occurs everywhere in the entire outer periphery of the bundle [3]. This results in a higher number of wrapper fibers in the yarn. One possible explanation for the reduction in elongation is the decrease in fiber slippage due to better grip by wrapper fibers. Possibly the drop in hairiness values is another result of better wrapping.




Visual comparison of vortex and air jet yarns showed that there were no apparent tendencies of cotton or polyester fibers to become either wrapper or core fibers in blended yarns. Although this study did not provide enough information to reach a consistent conclusion, examination of these yarns under the microscope showed that vortex yarns have more ring like appearance and a higher number of wrapper fibers compared to air jet yarns (Figure 4.)

The results from the evenness and tensile testing agreed with the earlier findings that vortex yarns had better evenness and tenacity values compared to air jet yarns (Figure 5 and Figure 6.)


Conclusion
This study revealed that MVS spinning technology is favorable for cotton spinning and produces a yarn with more ring like appearance compared to MJS spinning technology. However, more in depth study is required to understand the structure of vortex yarns.

Energy control in spinning

Energy audit is a preliminary activity towards instituting the energy control programs in an establishment. Energy audit increases awareness of energy related issues among plant personnel, making them more knowledgeable about proper practices that leads to cost reduction. A medium scale spinning mill at Coimbatore has been selected for the study and energy audit has been carried out in a most systematic way. Energy audit has revealed some important factors that affect the efficiency of motors, materials and energy balance and specific energy consumption at various level in that mill. The necessity of an information system for better energy conservation practice is one of the important findings of this work. This paper presents the possible methods of energy conservation that have been identified the spinning open lion, humidification and lighting, of a spinning mill.


K Keywords : Spinning mill, Energy conservation, Motor loading.
INTRODUCTION
The implementation of energy conservation programmes in spinning mills have gained wide acceptance in the background of the rising cost of commercial energy. The three major factors for energy conservation are high capacity utilization, fine tuning of equip­ment and technology upgradation. This paper concentrates on the application of these three concepts to a spinning mill,
The methodology adopted for conducting the detailed energy audit is:
¨ Basic data collecting on (i) list of power consuming equipment, (ii) production capacities of the major equip­ment and (iii) operating parameters.
¨ Measurement of operating parameters of various equip­ments to estimate their operating efficiency.
¨ Analysis of data collected to develop specific energy saving proposals.
· Presentation on the findings of the detailed energy audit. DESCRIPTION OF THE PLANT
The spinning mill considered for the study comes under medium scale category. Some important details of the mill are:
· Yarn manufacturing is carried out using state-cf-art textile equipment.
· Daily spinning capacity is 10 000 kg of yarn and number of spindles are 45 072.
· The mill operates continuously throughout the year.
· Major energy sources are electricity and high speed diesel (11513).
· Break up of the energy consumption per year is as follows.

· Generator power production is not separated and the
calculations are done on units of energy consumed.
· Contract demand with Tarnilnadu Electricity Board is for 1800 kVA per month.
Major Consumption Points
· Ring frames
· Humidification plant
¨ Winding
¨ Carding
¨ Blow room
¨ Heating lamps
¨ Lighting

Process Flowchart
Figure I briefly outlines the various processes involved in the manufacture of yarn in the mill.
Energy Audit Processes
Figure 2 shows the energy auditprocesses carried out in the mill.

The details of the energy audit processes arc:
· Classification of machines was carried out from the power rating of the load and type of load for which they are used.
· Information about the machines collected includes method of power transmission, loading sequence, sources of energy wastage and method of control.
· Energy against power rated data was used for the selec­tion of machines for detailed energy audit.
· To identify the methods for energy conservation, following points were considered.
(i) alternate to reduce/avoid energy losses
(ii) alternate to reduce down time
(iii) alternate to optimum selection
Necessity of an Information System for Better Energy Conservation Practices
Energy cost is one of the largest component of conversion cost incurred by the spinning mill. At present, energy related data are collected manually in the spinning mills which involves consi­derable amount of lime, cost and possible inaccuracies. Online information, on the other hand. provides quick, continuous and accurate results, which will be very much useful in decision making.
DATA ANALYSIS AND RECOMMENDATIONS
Power consumption pattern in the spinning mill is shown in Figure 3.
It shows that spinning is the major power consuming operation and uses 44.83% of total energy. The second largest use of energy (12.67%) is in humidification plant. The heating lamps use 9.54% of the total energy. Carding uses 7.44% of total energy and the share of the winding section is 6.21% of total energy. Drawing, simplex, doubling, lighting and other operations use the remaining energy.
Energy Factors in the Selection of Electric Motors
Choosing a motor for a particular application is based on many
factors such as the requirements of the driven equipment, service


conditions, motor efficiency and motor power factor. Table 1 and Table 2 show the actual observations of the present work on motor loading in the spinning mill. One of the important observation is that most of the motors were run at partial load conditions.
Figure 4 shows the loading of motors at various departments and how these deviate from SITRA standard (60%-80%) load.
THE MATERIAL AND ENERGY^-USE
The material and energy used in the spinning mill is shown in Figure 5 and Figure 6. Considerable amount of energy saving can he done by the reuse of these waste materials. Such usage conserves both energy and resources by reducing the need for buying new raw material and associated processing and transport cost.
Specific energy consumption and cost fore= each energy consuming
given ⁱⁿ Table 3 which shows that ring frames use IA852
units Of electric energy per kilogram. ilia second largest consumer
of electric energy is carding with a specific energy cons umption
of 0.2088. Specific energy consumption of blow room is Q.1408.
Spindle of ring frames consumes 45% of power. Many manufac?
turers have nowadays developed energy saving spindles having
less weight and small wharf diameter. IL was observed that 10%

to 19% saving of energy is possible by using energy saving spindles. Spindle is a high consumer of energy and the effect of the weight of the tape on energy consumption is more. Economics of SITRA energy saving tape with respect to the least expensive laminated synthetic tape is brought out, which shows that the former gives a saving of 41.21% per tape over the latter.




HUMIDIFICATION PLANT
The summer and winter conditions are the main designing factor for these plants. The supplyof air quantity required is worked out considering the adverse condition in summer. In order to save energy in winter and monsoon seasons, fan speed can be reduced and this will maintain the required humidity condition in the department. The outside heat load can also be reduced by roof cooling and insulation of roof.
LIGHTING
Most of the fittings are twin tube lights. The suggestion is to replace conventional copper chokes with energy efficient copper chokes for the identified fluorescent fittings. The estimation of saving is shown in Table 4. .
MOTORS
Automatic Star-delta Connector (ASDC)
When three-phase motor has a star-delta starter, ASDC is fitted to sense the load current and if it is below set value, delta connection of phases is switched back to star. Thus, the phase voltage changes is from 415 V to 230 V. The magnetizing current reduces at lower load and PF is improved leading to energy saving
The use of soft start corn energy saver helps to save energy in the following ways.
· continuously senses the load
¨ applies voltage automatically in accordance with load factor
· supplies energy needed to perform work
· provides smooth accelerating facilities
A proposal was given to install soft start cum energy saver for the motors in the identified simplex machines.
Yarn production results in a variety of waste materials and the wastage reduction proposals suggested for this mill are:
· Good material handling practices.
¨ Educating the workers on the impact of waste on energy (the price of yarn and waste).
¨ Demonstration to the workers about waste saving methods7.
CONCLUSION
In this paper, an attempt has been made to show the approach in identifying the operations in a spinning mill where significant energy savings can be achieved. Final decision regarding the desirability of implementation of any process modification should be based upon the analysis of all the costs reunited to achieve the anticipated savings, In the spinning m ill, humidifica­tion plant, lighting and motors consume most of the energy and hence all efforts have to be concentrated in these areas to save energy. Evaluation of demand pattern, properly scheduling the operations for various departments result in considerable energy saving. Energy use has to be monitored continuously with the help of an on-line information system for the effective energy utilization in a spinning mill. Energy conservation^-activities can be carried out by properly training the employees of the mill.