Spinning

                          Textile technology   spinning

Textile technology in spinning includes

• Mixing
• blow room 
• carding
• drawframe 
• comber 
• simplex 
• ring frame 
• winding 
• fibre testing 
• yarn testing etc

MIXING(COTTON)

Cotton is a hygroscopic material , hence it easily adopts to the atmospheric airconditions. Air temperature inside the mxing and blowroom area should be more than 25 degree centigrade and the relative humidity(RH%) should be around 45 to 60 %, because high moisture in the fibre leads to poor cleaning and dryness in the  fibre leads to fibre damages which ultimately reduces the spinnability of cotton.

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Cotton is a natural fibre. The following properties vary very much between bales (between fibres) fibre micronaire fibre length fibre strength fibre color fibre maturity   Out of these , fibre micronaire, color, maturity and the origin of growth results in dye absorption variation.
There fore it is a good practice to check the maturity , color and micronaire of all the bales and to
maintain the following to avoid dye pick up variation and barre in the finished fabric.
BALE MANAGEMENT :
In a particular lot

• Micronaire range of the cotton bales   used should be same for all the mixings of a lot
• Micronaire average of the cotton bales used should be same for all the mixings of a lot
• Range of color of cotton bales used should be same for all the mixings of a lot
• Average of color of cotton bales used should be same for all the mixings of a lot
• Range of matutrity coefficient of cotton bales used should be same for all mixings of a lot
• Average of maturity coefficient of cotton bales used should be same for all mixings of a lotPlease note, In practice people do not consider maturity coefficient since Micronaire variation and
  maturity variation are related to each other for a particular cotton.
  

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It the cotton received is from different ginners, it is better to maintain the percentage of cotton from different ginners throught the lot, even though the type of cotton is same.

It is not advisable to mix the yarn made of out of two different shipments  of same cotton. For example , the first shipment of west african cotton is in january and the second shipment is in march, it is not advisable to mix the yarn made out of these two different shipments.  If there is no shadevariation after dyeing, then it can be mixed.
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According to me, stack mixing is the best way of doing the mixing compared to using
automatic bale openers which picks up the material from 40 to 70 bales depending on the length of
the machine and bale size, provided  stack mixing is done perfectly. Improper stack mixing will lead to BARRE or SHADE VARIATION  problem.  Stack mixing with Bale opener takes care of short term blending and two mixers in series takes care of long term blending.
why?

• Tuft sizes can be as low as 10 grams and it is the best way of opening the material(nep creation will be less, care has to be taken to reduce recyling in the inclined lattice)
• contaminations can be removed before mixing is made
• The raw material  gets   acclamatised to the required temp and R.H.%, since it is allowed to stay in the room for more than 24 hours and the fibre is opened , the fibre gets conditioned well.Disadvantages:
  
• more labour is required
• more space is required
• mixing may not be 100% homogeneous( can be overcome by installing double mixers)
  If automatic bale opening machine is used the bales should be arranged as follows
  let us assume that there are five different micronaires and five different colors in the mixing,
  50 bales are used in the mxing. 5 to 10 groups should be made by grouping the bales in a mixing so that each group will have average micronaire and average color as that of the overall mixing. The
  position of a bale for micronaire and color should be fixed for the group and it should repeat in the
  same order for all the groups
  
  It is always advisable to use a mixing with very low Micronaire range.Preferably .6 to 1.0 . Because
  
• It is easy to optimise the process parameters in blow room and cards
• drafting faults will be less
• dyed cloth appearance will be better because of uniform dye pickup etc
  It is advisable to use single cotton in a mixing , provided the length, strength micronaire ,
  maturity coefficient and trash content of the cotton will be suitable for producing the required counts.  Automatic bale opener is a must if more than two cottons are used in the mixing, to avoid BARRE or SHADE VARIATION problem.
  
  It is better to avoid  using the following cottons
  
• cottons with inseparable trash (very small size), even though the trash % is less
• sticky cotton (with honey dew or sugar)
• cotton with low maturity co-efficient
  
  Stickiness of cotton consists of two major causes. Honeydew from Whiteflies and aphids and high level of natural plant sugars. The problems with the randomly distributed honey dew contamination often results in   costly proudction interruptions and requires immediate action often as severe as discontinuing the use of contaminated cottons.An effective way to control cotton   stickiness in processing is to blend sticky and non-sticky cotton.  Sticky cotton percentage should be less than 25%.
  
  
  
  

  BLOWROOM

  
  
  

  Basic operations in the blowroom:

  1. 
     

     opening

     
     
  2. 
     

     cleaning

     
     
  3. 
     

     mixing or blending

     
     
  4. 
     

     microdust removal

     
     
  5. 
     

     uniform feed to the carding machine

     
     
  6. 
     

     Recycling the waste

     
     
     

  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.
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  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
      
      
      1. two feed rollers( clamped)
      2. feed roller and a feed table
      3. 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 recommeded due to various reasons.
    • It is better to control the climate inside the department when sticky cotton is used. Low temperature
      ( around 22 degree celcius) 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 buoyanccy differences.
    • General factors which affect the degree of opening , cleaning and fibre loss are,
      
      
      1. thickness of the feed web
      2. density of the feed web
      3. fibre coherence
      4. fibre alignment
      5. size of the flocks in the feed (flock size may be same but density is different)
      6. the type of opening device
      7. speed of the opening device
      8. degree of penetration
      9. type of feed (loose or clamped)
      10. distance between feed and opening device
      11. type of opening device
      12. type of clothing
      13. point density of clothing
      14. arrangement of pins, needles, teeth
      15. speeds of the opening devices
      16. throughput speed of material
      17. type of grid bars
      18. area of the grid surface
      19. grid settings
      20. airflow through the grid
      21. condition of pre-opening
      22. quantity of material processed,
      23. position of the machine in the machine sequence
      24. feeding quantity variation to the beater
      25. ambient R.H.%
      26. ambient teperature
      
      
      
    • 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
    
    
    

    CARDING

    INTRODUCTION
    
    
    

    "Card is the heart of the spinning mill" and "Well carded is half spun" are two proverbs of the experts.
    These proverbs inform the immense significance of carding in the spinning process.High production in carding
    to economise the process leads to reduction in yarn quality.Higher the production, the more sensitive becomes
    the carding operation and the greater danger of a negative influence on quality.The technological changes that
    has taken place in the process of carding is remarkable. Latest machines achieve the production rate of
    60 - 100 kgs / hr, which used to be 5 - 10 kgs / hr, upto 1970.

    THE PURPOSE OF CARDING:
    
    
    

    1. to open the flocks into individual fibres
    2. cleaning or elimination of impurities
    3. reduction of neps
    4. elimination of dust
    5. elimination of short fibres
    6. fibre blending
    7. fibre orientation or alignment
    8. sliver formation

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    TECHNOLOGICAL POINTS IN CARDING
    
    
    

    • There are two types of feeding to the cards
      
      
      1. feeding material in the form of scutcher lap
      2. flock feed system (flocks are transported pneumatically)
      • lapfeeding
        
        
        1. linear density of the lap is very good and it is easier to maintain(uniformity)
        2. the whole installation is very flexible
        3. deviations in card output will be nil, as laps can be rejected
        4. autolevellers are not required, hence investment cost and maintenace cost is less
        5. transportation of lap needs more manual efforts( more labour)
        6. lap run out is an additional source of fault, as it should be replaced by a new lap
        7. more good fibre loss during lap change
        8. more load on the taker-in, as laps are heavily compressed
        
        
        
      • flock feeding
        
        
        1. high performance in carding due to high degree of openness of feed web
        2. labour requirement is less due to no lap transportaion and lap change in cards
        3. flock feeding is the only solution for high prouduction cards
        4. linear density of the web fed to the card is not as good as lap
        5. installation is not felxible
        6. autoleveller is a must, hence investment cost and maintenance cost is more
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      • Type of flock feed(chute feed)
        
        
        1. there are two basic concepts of flock feed
           
           
           1. one piece chute without an opening device
           2. two piece chute with an opening system
           
           
           
        2. one piece chute is simple, economical and requires little maintenance
        3. two piece chute is complex, expensive, but delivers a uniform batt.
        4. One piece chut is a closed system, i.e.excess flock returns to the distrbutor, if too much material is present,
           neps can be increased
        5. one piece chute is not flexible to run different mixings
        6. layout restrictions are more with one piece chute
        
        
        
      • A feeding device is a must to feed the web to the Taker-in region and it should perform the following tasks
        
        
        1. to clamp the batt securely throughout its width
        2. to grip the fibres tightly without slippage during the action of taker-in
        3. to present the fibres in such a manner that opening can be carried out gently
        
        
        
      • The divertor nose(sharp or round) and the length of the nose(guide surface) have a significant influence on
        quality and quantity of waste removed. Shart nose divertor avoids fibre slippage but the opening action is not gentle.
        If the length of the guide surface is too short, the fibres can escape the action of the taker-in. They are scraped
        off by the mote knives and are lost in the waste receiver.
      • Feed roller clothed with sawtooth is always better , because it gives good batt retention. Thus the opening effect
        of the taker-in is more as it is in combing
      • Rieter has devloped a "unidirectional feed system" where the two feed devices(feed roller and feed plate
        are oppositely arranged when compared with the conventional system. i.e. the cylinder is located below and
        the plate is pressed against the cylinder by spring force. Owing to the direction of feed roller, the fibre batt
        runs downwards without diversion directly into the teeth of the taker-in(licker-in) which results in gentle
        fibre treatment. This helps to reduce faults in the yarn.
      • The purpose of the taker-in is to pluck finely opened flocks out of the feed batt, to lead them over the
        dirt eliminating parts like mote knives, combing segment and waste plates, and then to deliver the fibres to the
        main cylinder. In high production cards the rotational speed ranges from 700-1400
      • The treatment for opening and cleaning imparted by Taker-in is very intensive, but unfortunately not very
        gentle.Remember that around 60% of the fibres fed to the main cylinder is in the form of individual fibres.
      • The circumferential speed of Taker-in is around 13 to 15 m/sec and the draft is more than 1000.It clearly
        shows that fibre gets deteriorated at this opening point. Only the degree of deterioration can be controlled
        by adjusting the following
        
        
        1. the thickness of the batt
        2. the degree of openness of the rawmaterial
        3. the degree of orientation of the fibres
        4. the aggressiveness of the clothing
        5. the distance between the devices
        6. the rotational velocity of the taker-in
        7. the material throughput
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      • Latest TRUTZSCHLER cards work with three licker-ins compared to one liker-in.The first one is constructed as
        needle roll. This results in very gentle opening and an extremely long clothing life for this roll. The other two
        rollers are with finer clothing and higher speeds, which results in feeding more %of individual fibres and
        smallest tufts compared to single lickerin, to the main cylinder. This allows the maing cylinder to go high
        in speeds and reduce the load on cylinder and flat tops. There by higher productivity is achieved with good
        quality. But the performance may vary for different materials and different waste levels.
      • between the taker-in and main cylinder , the clothings are in the doffing disposition. It exerts an influence
        on the sliver quality and also on the improvement in fibres longitudinal orientation that occurs here.
        The effect depends on the draft between main cylinder and taker-in.The draft between main cylinder and taker-in
        should be slightly more than 2.0.
      • The opening effect is directly proportional to the number of wire points per fibre. At the Taker-in
        perhaps 0.3 points/ fibre and at the main cylinder 10-15 points /fibre.If a given quality of yarn is required,
        a corresponding degree of opening at the card is needed. To increase production in carding, the number of points
        per unit time must also be increased. this can be achieved by
        
        
        1. more points per unit area(finer clothing)
        2. higher roller and cylinder speeds
        3. more carding surface or carding position
        speeds and wire population has reached the maximum, further increase will result in design and technological
        problems. Hence the best way is to add carding surface (stationary flats). Carding plates can be applied at
        
        
        
        1. under the liker-in
        2. between the licker-in and flats
        3. between flats and doffer
        
        
        
      • Taker-in does not deliver 100% individual fibres to main cylinder. It delivers around 70% as small flocks
        to main cylinder. If carding segments are not used, the load on cylinder and flats will be very high and carding
        action also suffers. If carding segemets are used, they ensure further opening, thinning out and primarily,
        spreading out and improved distribution of the flocks over the total surface area.carding segments bring the following advantages
        
        
        1. improved dirt and dust elimination
        2. improved disentanglement of neps
        3. possibility of speed increase (production increase)
        4. preservation of the clothing
        5. possibility of using finer clothings on the flats and cylinder
        6. better yarn quality
        7. less damage to the clothing
        8. cleaner clothing
        
        
        
      • In an indepth analysis, all operating elements of the card were therefore checked in regard to their
        influence on carding intensity. It showed that the "CYLINDER-FLATS" area is by far the most effective
        region of the card for.
        
        
        1. opening of flocks to individual fibres
        2. elimination of remaining impurities(trash particles)
        3. elimination of short fibres( neps also removed with short fibres)
        4. untangling the neps
        5. dust removal
        6. high degree of longitudinal orientation of the fibres
        
        
        
      • The main work of the card, separation to individual fibres is done between the main cylinder and the flats
        Only by means of this fibre separation, it is possible to eliminate the fine dirt particles and dust.
        When a flat enters the working zone, it gets filled up very quickly. Once it gets filled, after few seconds,
        thereafter , hardly any further take-up of fibres occurs, only carding.Accordingly, if a fibre bundle does
        not find place at the first few flats, then it can be opened only with difficulty.It will be rolled between
        the working surfaces and usually leads to nep formation
      • In princile, the flats can be moved forwards or backwards, i.e. in the same direction as or in opposition
        to the cylinder.In reverse movement, the flats come into operative relationship with the cylinder
        clothing on the doffer side. At this stage, the flats are in a clean condition. They then move towards
        the taker-in and fill up during this movement.Part of their receiving capacity is thus lost, but sufficient
        remains for elimination of dirt, since this step takes place where the material first enters the flats.
        At this position, above the taker-in, the cylinder carries the material to be cleaned into the flats. The
        latter take up the dirt but do not transport it through the whole machine as in the forward movement system.
        Instead , the dirt is immediately removed from the machine. Rieter studies show clearly that the greater part
        of the dirt is hurled into the first flats directly above the taker-in.
      • Kaufmann indicates that 75% of all neps can be disentagled, and of these about 60% are in fact
        disentagled. Of the remaining 40% disentaglable nep
        
        
        1. 30-33% pas on with the sliver
        2. 5-6% are removed with the flat strips
        3. 2-4%are eliminated with the waste
        The intensity of nep separation depends on
        
        
        1. the sharpness of the clothing
        2. the space setting between the main cylinder and the flats
        3. tooth density of the clothing
        4. speed of the main cylinder
        5. speed of the flat tops
        6. direction of flats with reference to cylinder
        7. the profile of the cylinder wire
        
        
        
      • The arrangement of the clothing between the cylinder and the doffer is not meant for stripping action,
        It is for CARDING ACTION.This is the only way to obtain a condensing action and finally to form a web. It has both
        advantages and disadvantages.The advantage is that additional carding action is obtained here and it differs
        somewhat from processsing at the flats.A disadvantage is that leading hooks and trailing hooks are formed
        in the fibres , beause the fibres remain caught at one end of the main cylinder(leading hook) and some times on
        the doffer clothing(trailing hook).
      • There are two rules of carding
        
        
        1. The fibre must enter the carding machine, be efficiently carded and taken from it in as little time as possible.
        2. The fibre must be under control from entry to exit
        
        
        
      • Carding effect is taking place between cylinder and doffer because, either the main cylinder clothing rakes
        through the fibres caught in the doffer clothing, or the doffer clothing rakes thro the fibres on the main cylinder.
        Neps can still be disentangled here, or non-separated fibre bundles can be opened a bit in this area and
        can be separated during the next passage through the flats
      • A disadvantage of web-formation at the card is the formation of hooks. According to an investigation by
        morton and Yen in Manchester, it can be assumed that
        
        
        1. 50% of the fibres have trailing hooks
        2. 15% have leading hooks
        3. 15% have both ends hooked
        4. 20% without hooks
        
        
        
      • Leading hooks must be presented to the comber and trailing hooks to the ring spinning frame.
        There must be even number of passages between card and comber and odd number between the card and ringframe.