Ultrasonic Technology in Nonwoven and Textile Industry


Flexible technology for a flexible market

Today’s textile and nonwoven market is so complex that fields of application, production techniques and technologies for further processing as well as the variety of new products are difficult to grasp, even for specialists.The variety of new composite materials of fleece, paper, films and fabric as well as the numerous possibilities in terms of combinations have one requirement in common: a safe and reliable process.

Ultrasonics is also the method of choice for these materials, for example for parting fabrics so that there is no thickening of the material along the cut edges.

No consumables such as glue, staples or sewing thread are needed. The fabric remains intact, because no external thermal energy is directed into the fleece. Position, shape and displacement of the welding points can even support the desired properties of the composite.

Textiles is thus a field where ultrasonic technology can prove its uniqueness.

The Functioning Principle of Ultrasonic Welding

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Low frequency mains voltage is transformed into high frequency electrical energy. A converter connected in line converts these electrical oscillations into mechanical vibrations. This is done using a piezoelectric transducer having an efficiency above 95 %.

The mechanical vibrations are transferred to a transformer element coupied to the converter, the so-called booster. This booster optimises the amplitude for the horn.

The horn is individually manufactured for each application and transfers the ultrasonic energy to the material to be processed. To build up a mechanical clamping force, a so-called anvil is required enabling the energy to effect melting on account of physical processes (internal and external absorption).

The Optimum Process for any Application

Cycle-controlled process

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The actuator applies a defined pressure onto the anvil and hence onto the part to be welded between the two components. Usually, the ultrasonic irnpulse applied  simultaneously is time-controlled. Using the weld depth or the amount of energy applied as criteria for deactivation is also possible.

Main fields of application for cyclecontrolled welding:

  • Overlapping welding of belts and tapes
  • Linear welding of fabric and nonwoven
  • Welding textile materials with thermoplastic contents
  • Joining the end of a material strip to the start of a roll to prevent costintensive drawing in of material into the production equipment.

Seal and cut edges can also be manufactured to excellent quality. This only requires a special design of horn and anvil which is important for the following particular applications:

  • Cut belt strips to length and/or punching
  • Parting of edge binding for blankets
  • Manufacturing buttonholes and eyes applying a certain structure to the rim in order to leave the impression of a sewn edge
  • Parting colour ribbons in bureau machine industry

Continuous Process

Two or more overlapping material strips are fed between horn and anvil which, if required, is rotating. Again, different systern combinations are possible:

Fixed Horn/Rotating Anvil

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This is the most commonly applied combination. Material strips (e. 9. fleece for use in agriculture) are joined at very high speeds using special profile wheels. Using profile wheels, sandwich structures can be generated. Combinations of different materials such as paper, films and textiles are particularly interesting applications. This combination can also be used for cutting processes. This usually involves cutting without sealing or with only slight edge sealling. The extension of the service life as well as the reduction of the cutting force and hence an increased cutting speed are strong arguments for the application of ultrasonic technology. Non-thermoplastic materials can also be cut. In this case ultrasonic energy supports breaking of the materials. Maximum precision is of course a prerequisite in such applications.

Rotating Horn/Rotating Anvil

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In this combination horn and anvil serve both to weld and to transport the welded product. In most cases both horn and anvil are driven synchronously. As in this system only a limited amplitude can be generated. This method is usually used for thin materials having a low mass per unit area.

Fixed HornlFixed Anvil

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This combination is usually used for cutting/ parting applications with simultancous sealing. However, it can also be used for continuous welding of paper, films, or textiles.

 

 

 

Refrance: BRANSON BROUCHER

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Automatic bale openers or pluckers


Modern mills now a day’s uses automatic bale openers or feeders in place of conventional hopper bale openers for more accurate mixing/ blending and also helps to eliminate mane power.

Modern bale pluckers can be mainly classified into two categories viz.

1. Moving bale type

The first generation bale opening machines were mostly stationary. Only the bales were moved either backward or forward or in a circle. The examples of these types of machines are Trutzschler multi-bale plucker, karousel-beater type opener by Rieter, etc.

2. Moving beater type

The second generation machines are of the travelling type i.e. they move past the bales of the layout and extract material from top to bottom. Travelling machines have the advantages that more bales can be processed as an overall unit, and thus better long-term blend is achieved. It should be noted however that these machines extract material only in batches, i.e. they can process only one, two or maximum three bales simultaneously. If long term blend is needed to be achieved, then mixing machines must be included downstream from the bale opener. These machines are completely electrically controlled and extract material evenly from all bales evenly, independently of varying bale density.

In concept, these machines are most commonly utilized now a day. Machines similar to uni-floc by Rieter are developed by various other manufactures viz. Optimix by Hargeth Hollingsworth, B12 by marzoli and blendomat by Trutzschler. The latest uni-floc provided in modern Rieter blow room line in place of the hopper bale opener is UNI-FLOC A-11.

UNIFLOC A-11

· OPERATIONAL PRINCIPLE

The A 11 UNI-floc processes cotton from all sources and manmade fibres in staple lengths of up to 65 mm. The bales being opened are placed lengthwise or crosswise on both sides of the bale opener, and the take-off unit can process up to four different assortments.

Reduction of the raw material into micro-tufts is assured by the patented double teeth on the take-off roller and the grid with closely set clamping rails. The unique geometry of the double teeth ensures the uniform treatment of the entire bale surface. Retaining rollers travelling with the take-off unit prevent bale layers from sloughing and ensure precise, controlled operation over the entire height of the bale. The A 11 UNI-floc still produces small tufts, even at maximum output of 1400 kg/h.

The take-off unit is lowered by a preselected or computed distance at each pass. Running-in and running-out programs compensate for the differing hardness of the bales over their cross section and ensure a uniform level of production. The fan incorporated in the swivelling tower extracts the opened tufts and feeds them into the tuft channel running between the guide rails. Transport to the following machine is pneumatic.

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Figure 1 OPERATIONAL PRINCIPLE OF UNI-FLOC A-11

· DISTINGUISHING FEATURES OF UNI-FLOC A-11

The UNI-floc is basically one type of opening which is most commonly utilized in place of “hopper bale openers”. The distinguishing features of UNI-floc are:

1. Bale opening into micro-tufts for effective cleaning and dust extraction.

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Figure narrow grid gauge for micro-tufts

Micro tufts are the basic requirement for the production of yarn quality. Trash and dust can only be removed from natural fibres gently and efficiently on the surface of the tufts.

The take-off unit of the UNI-floc is considered to be the “heart” of the system as it is responsible for micro tuft formation. The patented take-off roller and the grid design with small gaps between the clamping rails enables small fibre tufts ( micro tufts ) to be extracted. The twin-tooth profile ensures uniform, gentle and efficient extraction of the tufts, also irrespective of the take-off roller’s direction of rotation.

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Figure comparison of output and tuft size in modern machine(UNI-floc A-11) to conventional bale opener

2. Uniform take-off of bale lay-down by means of “BALE PROFILEING”

Bale Profiling guarantees totally uniform bale take-off. The height profile of the bale lay-down is precisely detected by light barriers and memorized. Scanning is performed at a constant speed of 9 m/min. Tufts are already taken off in the profiling phase. Continuous feeding of the subsequent machines is thus ensured from the outset.

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Figure uniform take-off of bale lay-down by means of bale profiling

During the subsequent passes the bales are opened at the preselected speed of travel and take-off depth. In the process the system automatically compensates for differences in height in the bale profile. Labour-intensive manual levelling is eliminated. After the required height range, take-off depth and speed of travel have been entered for each group of bales, take-off proceeds fully automatically.

3. Simultaneous processing of up to 4 assortment

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We can lay down as many as 130 bales in four groups on each side of the machine. This means that four assortments can be processed automatically at the preselected take-off speed and with the required production volume.

4. Patented, individually interchangeable double teeth on the opening roller

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Figure Patented, individually interchangeable double teeth

The double teeth enable maintenance intervals to be halved. The teeth are mounted individually. They can easily and quickly be replaced if required, without removing the take-off roller. This explains the exceptionally high operational readiness of the A 11Uni-floc

5. Processing of cotton from all sources and man-made fibres in staple lengths of up to 65 mm

 

6. Output of up to 1 400 kg/h (carded sliver)

7. Bale lay-down over a length of 7.2 to 47.2 meters

A bale lay-down of overall lengths of 7.2 to 47.2 meters and two take-off of unit lengths of 1 700 mm and 2 300 mm. The maximum version is capable of accommodating raw material up to 40 000 kg. This ensures flexible, economical and largely autonomous processing on UNI-floc A-11.

8. Take-off width selectable between 1 700 mm and 2 300 mm

 

9. Graphic interface for easy, intuitive operation at the control panel

The control panel is placed facing the extraction duct, providing a clear view and safety for operating the machine. Setting and control of the A 11 UNI-floc can easily be performed at the screen.

10. Interface to higher-level control and information systems available

In the interests of optimum monitoring of the installation as a whole, this modern machine control unit can be connected to the UNI-control or UNI-command control system. UNI-control and NI command also provide the interface to Reiter’s higher-level SPIDER web mill monitoring system.

 

11. Maximum yield due to optimized processes

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PROCESS PARAMETER IN BLOW ROOM


With all harvesting methods, however, the cotton seed, together with the fibres, always gets into the ginning plant where it is broken up into trash and seed-coat fragments. This means that ginned cotton is always contaminated with trash and dust particles and that an intensive cleaning is only possible in the spinning mill.

Nep content increases drastically with mechanical harvesting, ginning and subsequent cleaning process. The reduction of the trash content which is necessary for improving cotton grade and apperance unfortunately results in a higher nep content level.

The basic purpose of  Blow room is to supply

  • small fibre tufts
  • clean fibre tufts
  • homogeneously blended tufts if more than one variety of fibre is used

to carding machine  without increasing  fibre rupture, fibre neps , broken seed particles and without removing more  good fibres.

The above is achieved by the following processes in the blowroom

  1. Pre opening
  2. pre cleaning
  3. mixing or blending
  4. fine opening
  5. dedusting

CLEANING EFFICIENCY:

Cleaning efficiency of the machine is the ratio of the trash removed  by the machine to that of  total trash fed to the machine, expressed as percentage

Cleaning efficiency % =(( trash in feed % – trash in del %) x 100) / (trash in feed%)

Following are the basic parameters  to be considered in Blowroom process.

  • no of opening machines
  • type of beater
  • type of beating
  • Beater speed
  • setting between feed roller and beater
  • production rate of individual machine
  • production rate of the entire line
  • thickness of the feed web
  • density of the feed web
  • fibre micronaire
  • size of the flocks in the feed
  • type of clothing  of the beater
  • point density of clothing
  • type of grid and grid settings
  • air flow through the grid
  • position of the machine in the sequence
  • amount of trash in the material
  • type of trash in the material
  • temp and relative humidity in the blow room department

PREOPENING:

Effective preopening results in smaller tuft sizes, thus creating a large surface area for easy  and efficient removal of trash particles by the fine openers.

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Fig:-BO-c bale opener

If MBO (Rieter) or  BO-c ( Trutzschler) type of machine is used as a first machine

  • the tuft size in the mixing should be as small as possible. Normally it should be less than 10 grams
  • since this machine does not take care of long term blending, mixing should be done properly to maintain the homogenous blending
  • the inclined lattice speed and the setting between inclined lattice and clearer roller decides the production of the machine
  • the setting between inclined lattice and clearer roller decides the quality of the tuft
  • if  the setting is too close, the tuft size will be small, but the neps in the cotton will be increased due to  repeated action of the  inclined lattice pins on cotton.
  • the clearance should be decided  first to confirm the quality, then inclined lattice speed can be decided according to the   production required
  • the setting of inclined lattice depends upon the fibre density, fibre micronaire and the tuft size fed. If smaller tuft is fed to the feeding conveyor, the fibre tufts will not be recycled many times, hence the neps will be less.
  • if the machine is with beater, it is advisable to use only disc type beater. Saw tooth and Pinned beaters should not be used in this machine, because the fibre  damage at this stage will be very high and heavier trash particles will be broken in to small pieces.
  • the beater  speed  should be around 500 to 800 rpm depending upon the rawmaterial. Coarser the fibre,  higher the speed
  • the setting between feed roller to beater should be around 4 to 7 mm
  • this machine is not meant to remove trash ,  hence the fibre loss should also be less
  • trash removal in this machine will result in breaking the seeds, which is very difficult to remove
  • It is easier to remove the bigger trash than the smaller trash, therefore enough care should be taken to avoid breaking the trash particles
  • this machine is  just to open the tufts into small sizes so that cleaning becomes easier in the next machines.
  • the fibre tuft size from this  machine should be  preferably around 100 to 200 milligrams.
  • If tuft size is  small, removing trash particles becomes easier , because of large surface area

Unifloc11

Fig:- Unifloc11

If Uniflco11(Rieter) or Blendomat BDT 019(Trutzschler) is used as a first machine

  • It helps to maintain the homogeneity of the long term blending
  • cotton is opened gently without recyling as it is done in manual bale openers
  • with the latest automatic bale opening machines,  the tuft size can be as small as 50 to 100 grams without  rupturing the fibres
  • the opening roller speed should be around 1500 to 1800 rpm.
  • the depth of penetration of the opening  should be as minimum as possible for better quality
  • It is better to use this machine with one mixing or maximum two mixing at  the same.
  • If the production per feeding machine is less than 150 kgs, then four mixings can be recommended
  • production rate of this machine depends upon the no of mixings working at the same time
  • production rate depends  upon opening roller depth, traverse speed and the fibre tuft density
  • in general , the machine parameters should be set in such a way that  maximum number of take-off points are available  per unit time.
  • with the latest machines (Rieter -Unifloc A11), around 60% of take-off points are more compared to earlier machines

PRECLEANING:

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Fig: Uniclean B12

Precleaning should be gentle. Since removing finer trash particles is difficult , seeds and bigger trash particles should not be broken. Finer trash particles require severe treatment in Fine openers. This will lead to fibre damage and more nep generation. Therefore, precleaning should be as gentle as possible and no compromise on this. If preopening and precleaning are done  properly,  consistency in trash removal by fine openers is assured. Dust removal should be started in this machine. Enough care should be taken remove dust  in this process.

Rieter’s Uniclean B11 and Trutzschler’s Axiflow or Maxiflow  are the machines which does this work

  • the fibre treatment in this machine is very gentle because  the fibres are not gripped by the feed roller during beating.  Fibre tufts treated by the pin beater when it is carried by air medium
  • all heavy trash particles fall down before it is broken
  • cleaning efficiency of this machine is very high in the blow room line
  • Mostly all heavy seeds( full seeds) fall in this machine without any problem
  • around 50 pascal suction pressure should be maintained in the waste chamber for better cleaning efficiency
  • beater speed, air velocity through the machine, grid bar setting and gap between grid bars will affect the cleaning efficiency
  • higher the cleaning efficiency,  higher the good fibre loss, higher the nep generaion and higher the fibre rupture
  • the optimum cleaning means maximum cleaning performance, minimum loss of good fibres, a high degree of fibre preservation and minimum nep generation
  • Rieter has a unique concept called “VARIOSET”. With this machine, selective trash removal is possible. Waste  amount can be changed in a range of 1:10.

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fig: from Rieter which shows , degree of cleaning, fibre loss, neps, fibre damage.

  • with normal machines like Monocylinder or axiflow, a lot of trials to be conducted to arrive at optimum beater speed, air velocity(fan speed), grid bar setting and grid bar gap.
  • in general the beater speed is around 750 and  minimum 50 Pascal suction pressure to be maintained in the suction chamber

BLENDING:

  • Barre or streakiness is due to uneven mixing of different cottons. Hence mixing technology is a decisive factor in spinning mill technology
  • bigger the differences of cotton parameters like fineness, color and staple length, the greater the importance of mixing
  • if the cotton has honeydew, the intensive mixing of the rawmaterial is a precondition  for an acceptable running behaviour  of the complete spinning mill

following  fig is given by trutzschler for different  mixing requirements

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standard               standar- plus              high                   high-end

  • Trutzschler’s tandem mixing concept is an  ultimate solution, if the mixing requirement is very high. This principle guarantees a maximum homogeneous of the mix

FIG.Tandem mixing concept from TRUTZSCHLER:

FINE CLEANING:

Fine cleaning is done with different types of machines. Some fine cleaners are with single opening rollers  and some are with multiple opening rollers.

  • If single roller cleaning  machines are used, depending upon the  amount and type of trash in the cotton, the number of fine cleaning points can be either one or two.
  • If the production  rate is lower than 250 kgs and the micronaire is less than 4.0, it is advisable to use single roller cleaning machines instead of multiple roller cleaning machine.
  • Saw tooth beaters can be used, if trash particles are more and the machine is not using suction and deflector blades. i.e beater and regular grid bar arrangements
  • Normal beater speeds with saw tooth beater depends upon the production rate,  fibre micronaire and trash content
TYPE OF COTTON COTTON MICRONAIRE PROUDCTION RATE kgs/hr BEATER SPEED rpm
more trash 3.5 to 4.0 200 to 300 kgs /hr 600 to 750
less trash 3.5 to 4.0 200 to 300 kgs/hr 600 to 750
more trash 4.0 to 4.5 200 to 300 kgs 700 to 850
less trash 4.0 to 4.5 350 to 500 kgs 1000 and above
  • the number of wire points depends on the production rate and trash.
  • setting between feed roller and beater depends on the production rate and micronaire.  The setting should be around 2 to 3 mm.  Wider setting always result  in higher rawmaterial faults, if carding does not take care.
  • closer the setting between beater and mote knives, higher the waste collected. It is advisable to keep around 3 mm.
  • If it is a Trutzschler blowroom line, it is better to use  CVT1 ( single opening roller machine) if  roller ginned cotton  is used.
  • CVT3  or CVT4 machines with 3 or 4 opening rollers can be used for saw ginned cotton.
  • The cleaning points in CVT1, CVT3, CVT4 etc consists of opening roller, deflector blades, mote knives and suction hood. Trash particles released due to centrifugal forces are  separated at the mote knives and continuously taken away by the  suction. This gives better cleaning

FIG: trash removal concept in CVT cleaners:

  • suction plays a major role in these machines. If suction  is not consistent , the performance will be affected badly.  Very high suction will result in more white fibre loss and less suction will result in low cleaning efficiency.
  • The minimum recommended pressure in the waste chamber (P2) is 700 Pascal’s. It can be upto 1000 Pascal’s.
  • material suction (P1) should be around 500 Pascal’s
  • Whenever the suction pressure is changed, the deflector blade settings should be  checked
  • Deflector blade setting can not be same for all the three rollers or four rollers. The setting for deflector blades in the panel looks like this 3, 12, 30 for 1st, 2nd and 3rd deflector blades.
  • The deflector blade setting should be done in such a way that  the setting should be opened till the fibres start slipping on the deflector blade.
  • wider the deflector blade setting, higher the waste. If the setting is too wide, white fibre loss will be very high.
  • for saw ginned cottons, the above concepts helps a lot because of constant suction concentrated directly at the moteknives, ensures much removal of dust from the cotton.

DEDUSTING:

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Fig: Dustex

Apart from opening cleaning of rawmaterial, dedusting is the very important process in blowroom process.

  • normally dedusting  starts with precleaning
  • it is always better to have a separate machine like DUSTEX of TRUTZSCHLER  for effective dedusting
  • dedusting keeps the atmospheric air clean
  • dedusting in machines like unimix , ERM of Rieter is  good
  • stationary dedusting condensers can be used for this purpose
  • in exhausts of  unimix , condensers , ERM etc, positive pressure of 100 pascal should be maintained. Exhaust fan speed and volume should be accordingly selected
  • DUSTEX should be installed before feeding to the cards, because better the fibre  opening better the dedusting
  • fine openers like ERM, CVT cleaners also help in dedusting
  • It is always better to feed the material through condenser for a feeding machine of cards.  Because condenser continuously removes the dust from a small quantity of fibres  and the material  fed to the feeding machine is opened to some extent.
  • Since material is not opened well in Unimix, the dedusting may not be very effective, even though  dedusting concept in Unimix is very good
  • for rotor spinning dedusting is very important. It is better to use a machine like DUSTEX  after the fine opener.

OTHERS:

  • setting between feed rollers is different for different types. It should be according to the standard specified by the manufacturer.  For Unimix it should be around 1 mm.
  • it is advisable to run the fans at optimum speeds.  Higher fan speeds will increase the material velocity and will create  turbulence  in the bends.This will result in curly fibres which will lead to entanglements.
  • If the feeding to cards  is not with CONTI -FEED, the efficiency of the feeding machine should be minimum 90 % and can not be more than 95%.
  • if the cards are fed by CONTI-FEED system,  the feed roller speed variation should not be more than 10%.  If the variation is more, then the variation in tuft size also will be more. Hence the quality will not be uniform
  • If two feeding machines feed to  10 cards and the no of cards can be changed according the requirement, then frequent changes will affect the tuft size which will affect the quality, if the line is fixed with CONTI-FEED.
  • if contifeed system is tuned properly and there are no machine stoppages, continuous material flow will  result in better opening and even feeding to the cards
  • If the production rate per line is high, the reserve chamber  for  the feeding machine should be big enough to avoid long term feed variations.
  • it is advisable to reduce the number of fans  in the line.
  • fan speeds, layout of machines should be selected in such a way that material choking in the pipe line, beater jamming etc will not happen.  This will lead to quality problems
  • all blowroom machines should work with maximum efficiency. The feed roller speeds  should be selected in such a way that  it works atleast 90% of the running time of the next machine.
  • blow room stoppages will always affect the sliver quality both in terms of linear density and  tuft size. Blow room stoppages  should be nil in a mill
  • heavy particles like metal particles, stones should be removed using heavy particle removers , double magnets etc, before they damage  the opening rollers and other machine parts.
  • Number of cleaning  points are decided based on  type of ginning (whether roller ginned or saw ginned), the amount of trash, and the number of trash particles and the type of trash particles.
  • machinery selection should be based on the type of cotton and production requirement. If the production requirement of a blowroom line is less than 200 kgs,  CVT-4 cleaner can not be  recommended, instead CVT-1 can be used.
  • Since blow room requires more space and power, it is better to make use of the maximum production capacity of the machines
  • material level in the storage chambers  should be full  and it should never be less than 1/4 th level.
  • grid bars should be inspected periodically, damaged grid bars  should be replaced.
  • grid bars in  the front rows can be replaced earlier
  • if the cotton is too sticky, the deposits on the machine parts  should be cleaned atleast once in a week, before it obstruct the movement of the fibre
  • fibre rupture should be checked for each opening point.  2.5 % span length should not drop by more than 3% . If the uniformity ratio drops by more than 3%, then  it  is considered that there is fibre rupture.
  • high fan speed, which will result in high velocity of air will increase neps in cotton
  • nep is increased in the blowroom process.  The increase should not be more than 100%.
  • the nep increase in each opening machine should be checked  with different beater speeds and settings, and the optimum  parameters  should be selected. But please remember that everything should be based on  yarn quality checking.  e.g. if nep increase in blow room is  more and the beater speed or feed roller setting is changed, the tuft size will become more. This may result in bad carding quality. Sometimes if the neps are slightly more and the  fibre is well opened, the neps can be removed by cards and combers and the yarn quality may be better.  Therefore all trials should be done upto yarn stage.
  • No of neps and trash particles  after different processes is given below.(an approximate value)
  • Blow room machinery lay out should be desined in such a way that there should be minimum number of bends, and there should not be sharp bends  to avoid fibre entanglements.
  • fibre travelling  surface should be smooth and clean
  • temperature should be around 30 degrees and the humidity is around 55 to 60%.

A best blowroom can be achieved by selecting the following machines:

1.RIETER UNIFLOC- A11 ( pre opening)

2.RIETER UNICLEAN B11 (  pre cleaning)

3.TRUTZSCHLER MPM 6 + MPM6 ( two mixers for blending)

4.TRUTZSCHLER CVT-1 ( for  roller ginned cotton) CVT-3 ( for saw ginned)

5.CONTAMINATION DETECTOR from either BARCO OR JOSSI

6.TRUTZSCHLER  DUSTEX-DX ( for dedusting)

7.TRUTZSCHLER CONTI-FEED and others

But enough care should be taken to synchronise the machines for better performance  , and to run the line without any electrical system breakdowns.

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Metallic Card Clothing


INTRODUCTION:

As Carding machine design improved in 1950’s and 60’s, it became apparent that card clothing was a limiting factor Much time and effort was spent in the development of metallic card clothing.

· 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

· Control of fibres in a carding machine is the responsibility of the card clothing

· Following are the five types of clothing’s used in a Carding machine

  1. Cylinder wire
  2. Doffer wire
  3. Flat tops
  4. Licker-in wire
  5. Stationary flats

CYLINDER WIRE:

The main parameters of CYLINDER Card clothing

  1. Tooth depth
  2. Carding angle
  3. Rib width
  4. Wire height
  5. Tooth pitch
  6. Tooth point dimensions
  1. Shallowness of tooth depth reduces fibre loading and holds the fibre on the cylinder in the ideal position under the carding action of the tops. The space a fibre needs within the cylinder wire depends upon
    its Micronaire/denier value and staple length.
  2. The recent cylinder wires have a profile called “NO SPACE FOR LOADING PROFILE”(NSL). With this new profile, the tooth depth is shallower than the standard one and the overall wire height is reduced to 2mm , which eliminates the free blade in the wire. This free blade is responsible for fibre loading.Once the fibre lodges between the free blade of two adjacent teeth it is difficult to remove it.In order to eliminate the free blade, the wire is made with a larger rib width
  1. Front angle not only affects the carding action but controls the lift of the fibre under the action of centrifugal force. The higher the cylinder speed , the lower the angle for a given fibre. Different fibres have different co-efficient of friction values which also determine the front angle of the wire.
  2. If the front angle is more, then it is insufficient to overcome the centrifugal lift of the fibre created by cylinder speed. Therefore the fibre control is lost, this will result in increasing flat waste and more neps in the sliver.
  3. If the front angle is less, then it will hold the fibres and create excessive recycling within the carding machine with resulting over carding and therefore increased fibre damage and nep generation.
  4. Lack of parallelisation, fibre damage, nep generation, more flat waste etc. etc., are all consequences of the wrong choice of front angle.
  1. Each fibre has a linear density determined by its diameter to length ratio. Fine fibres and long fibres necessitates more control during the carding process. This control is obtained by selecting the tooth pitch which gives the correct contact ratio of the number of teeth to fibre length.
  2. Exceptionally short fibres too require more control, in this case , it is not because of the stiffness but because it is more difficult to parallelise the fibres with an open tooth pitch giving a low contact ratio.
  • RIB THICKNESS:
  1. The rib thickness of the cylinder wire controls the carding “front” and thus the carding power. Generally the finer the fibre, the finer the rib width. The number of points across the carding machine is determined by the carding machine’s design, production rate and the fibre dimensions. General trend is towards finer rib thicknesses, especially for high and very low production machines.
  2. Rib thickness should be selected properly, if there are too many wire points across the machine for a given cylinder speed, production rate and fibre fineness, “BLOCKAGE” takes place with disastrous results
    from the point of view of carding quality. In such cases, either the cylinder speed has to be increased or most likely the production rate has to be reduced to improve the sliver quality
  • POINT POPULATION:
    The population of a wire is the product of the rib thickness and tooth pitch per unit area. The general rule higher populations for higher production rates, but it is not true always. It depends upon other factors
    like production rate, fineness, frictional properties etc.
  • TOOTH POINT:
    The tooth point is important from a fibre penetration point of view. It also affects the maintenance and consistency of performance. Most of the recent cylinder wires have the smallest land or cut-to-point.
    Sharp points penetrate the fibre more easily and thus reduce friction, which in turn reduces wear on the wire and extends wire life.
  • BLADE THICKNESS:
    Blade thickness affects the fibre penetration. The blade thickness is limited by practical considerations,but the finer the blade the better the penetration of fibres. Wires with thin blade thickness penetrate the more easily and thus reduce friction, which in turn reduces wear on the wire and extends wire life.
  • BACK ANGLE:
    A lower back angle reduces fibre loading, but a higher value of back angle assists fibre penetration. Between the two extremes is an angle which facilitates both the reduction in loading and assists fibre penetration and at the same time gives the tooth sufficient strength to do the job for which it was designed.
  • HARDNESS OF WIRE:
    The cylinder wire needs to be hard at the tip of the tooth where the carding action takes place.The hardness is graded from the hard tip to the soft rib. High carbon alloy steel is used to manufacture a cylinder wire and it is flame hardened. Rib should not be hardened, otherwise, it will lead to mounting problems.

The design or type of clothing, selected for the fibre to be carded is important,but it is fair to state that within reason, an incorrect design of clothing in perfect condition can give acceptable carding quality whereas a correct clothing design in poor condition will never give acceptable carding quality. There is no doubt that the condition of the clothing’s is the most important single factor affecting quality at high rates of production. Wire condition and selection of wire are considered to be the two most important factors which influence the performance of modern high production carding machines.

· The condition of the clothing may be defined as the collective ability of the individual teeth of the clothing to hold on to the fibre against the opposing carding force exerted by other teeth acting in the carding
direction. For a given design of clothing the condition of the teeth determines the maximum acceptable production rate that can be achieved at the card.

· The speed of the main cylinder of card provides the dynamic force required to work on separating the fibres fed to the card but it is the ability of the carding teeth on the cylinder to carry the fibre forward against the opposing force offered by the teeth of the tops which determines the performance of the card. Increasing cylinder speed increases the dynamic forces acting upon the carding teeth and thus the condition of teeth becomes more important with increased speed.If the condition and design of the cylinder wire is poor, the teeth will not be able to hold onto the fibre through the carding zone, thus allowing some of the freed fibre to roll itself into nep.

DOFFER WIRE:

  1. The doffer is a collector and it needs to have a sharp tooth to pickup the condensed mass of fibres circulating on the cylinder. It also requires sufficient space between the teeth to be efficient in fibre transfer from the cylinder, consistent in the transfer rate and capable of holding the fibre under control until the doffer’s stripping motion takes control.
  2. A standard doffer wire has an overall height of approx. 4.0 mm to facilitate the deeper tooth which must have sufficient capacity to collect all the fibre being transferred from the cylinder to meet production requirements. Heavier webs require a deeper doffer tooth with additional collecting capacity to handle the increased fibre mass.
  3. The doffer wire’s front angle plays a very important part in releasing the fibre from the cylinder wire’s influence. A smaller angle has a better chance of enabling the doffer wire’s teeth to find their way under
    the fibres and to secure the fibre’s release from the cylinder with greater efficiency. A 60 degree front angle for Doffer has been found to give the optimum performance under normal carding conditions. Too small an angle results in cloudy web and uneven sliver whilst too large an angle results in fibre recirculation and nep generation.
  4. Having collected the fibre, it is important for the doffer to retain it until it is stripped in a controlled manner by the doffer stripping motion. The tooth depth, tooth pitch and rib width combine to create the space available for fibre retention within the doffer wire. Thus they directly influence the collecting capacity. If the space is insufficient, fibre will fill the space and any surplus fibre will be rejected. When
    the surplus fibre is left to recirculate on the cylinder, cylinder loading can take place. Unacceptable nep levels and fibre damage will also result. In severe cases pilling of the fibre will take place.
  5. The point of the doffer wire normally has a small land which helps to strengthen the tooth. The extremely small land of around 0.05 mm ensures that the doffer wire height is consistent, has no adverse effect on fibre penetration and is considered essential for efficient fibre transfer from the cylinder. The land has microscopic striations which are created during manufacturing or grinding. The striations help to collect the fibres from the cylinder and keep them under control during the doffing process.
  6. It has been found that a cut-to-point doffer wire penetrates the fibre better than does the landed point wire but is less likely to keep the fibre under control during the doffing process. Sometimes a cut-to-point doffer wire is accompanied by striations along one side of the tooth for this reason. Until recently 0.9mm rib thickness is standardised for doffer wire, regardless of production and fibre characteristics.This rib thickness has been found to give optimum results. However doffer wires with a 0.8mm rib thickness have been introduced for applications involving finer fibres.
  7. In general 300 to 400 PPSI(points per square inch) has been found to perform extremely well under most conditions. Doffer wire point population is limited by the wire angle and tooth geometry. Higher
    population for doffer does not help in improving the fibre transfer.
  8. As the production rate rises, the doffer speed also increases. The doffer is also influenced by the centrifugal force, as is the cylinder.But cylinder wire front angle can become closer to counter the effect
    of centrifugal force, to close the front angle on a doffer wire would reduce its collecting capacity and result in a lowering of the production rate. The solution is to use the wire with striations, which will hold the fibre until the doffer is stripped.
  9. The hardness of the doffer wire is a degree lower than that of the cylinder but sufficiently hard to withstand the forces generated in doffing and the resultant wear of the wire. The reason for this slightly lower hardness requirement is the longer and slimmer tooth form of the differ wire.
  10. The fibres which are not able to enter the wire will lay on top, i.e.completely out of control. There fore instead of being carded by the tops the fibres will be rolled. Similarly a fibre buried too deep
    within the cylinder wire will load the cylinder with fibre, weaken the carding action and limit the quantity of new fibres the cylinder can accept. Therefore, the production rate would have to be reduced.

LICKER-IN WIRE:

  1. Licker-in with its comparatively small surface area and small number of carding teeth, suffers the hardest wear of all in opening the tangled mass of material fed to it.
  2. Successful action of the Licker-in depends upon a penetrating sharp point rather than a sharp leading edge as with the cylinder wire. Therefore the licker-in wire cannot be successfully restored to optimum performance by grinding.
  3. The most satisfactory system to adopt to ensure consistent performance is to replace the licker-in wire at regular intervals before sufficient wear has taken place to affect carding quality.
  4. The angles most widely used are 5 degrees negative or 10 degrees.
  5. There is no evidence to suggest recommendation of a tooth pitch outside the range of 3 to 6 points per inch.
  6. It is better to use Licker-in roller without groove. Interlocking wires are used for such type of licker-ins. This avoids producing the eight precise grooves and to maintain them throughout its life. Interlocking wire is almost unbreakable and thus no threat to the cylinder, tops and doffer in the event of foreign bodies entering the machine.

FLAT TOPS:

  1. The flat tops are an equal and opposite carding force to the cylinder wire and it should be sharp,
    well maintained and of the correct design.
  2. The selection of flexible tops is very much related to the choice of cylinder wire, which in turn is related
    to the cylinder speed, production rate and fibre charactersitics, as previously stated.
  3. The modern top is of the semi-rigid type, having flexible foundation and sectoral wire. The points are
    well backed-off and side-ground to give the necessary degree of fineness. The strength of the top from a carding
    point of view is in the foundation and is affected by the number of plies and the type of material used.
    The position of the bend in the wire is determined by stress factors, at around 2:1 ratio along the length of the wire protrusion.
  4. The modern top is made from hardened and tempered wire to increase wear resistance , thus improving
    the life of the flat top.

· Life of the cylinder wire depends upon

  1. Material being processed
  2. production rate
  3. cylinder speed
  4. settings

· Wear is the natural and unavoidable side effect of the work done by the vital leading edge of the metallic wire tooth in coping with the opposing forces needed to obtain the carding action which separates fibre from fibre. When the leading edge becomes rounded due to wear, there is a loss of carding power because the point condition has deteriorated to an extent where the leading edge can no longer hold on to the fibre against the carding resistance of the flats. This ultimately leads to fibres becoming rolled into nep with consequent degradation of carding quality. Therefore it is important to recognise that, due to the inevitable wear which takes place during carding, metallic wire must be reground at regular intervals with the object of correctly resharpening the leading edge of each tooth.

· GRINDING:

  1. GRINDING A CUT-TO-POINT CYLINDER WIRE:
    1. Wire points of cylinder have become finer and the tip is cut-to-point.Because of this new profile, it has become necessary to recommend a little or no grinding of the cylinder wire following mounting.
      TSG grinding machine of GRAF(wire manufacturer) can be used to sharpen these modern wires. TSG grinding is a safe method of grinding.
    2. Before grinding , the wire should be inspected with a portable microscope to ascertain the wear. Based on this and the wire point land width, no of traverse for TSG grinding should be decided. If the width of the wire point tip is bigger and the wear out is more, the number of traverse during grinding should be more. For a new wire, 3 or 4 traverses may be enough. But it may require 10 to 30 traverses for the last grinding before changing the wire, depending upon the maintenance of the wire.
  2. GRINDING A NORMAL CYLINDER AND DOFFER WIRE:
    1. The first grinding of the metallic wire on the cylinder and doffer is the final and most important step leading up to providing the card with a cylinder in the best possible condition for carding well at maximum production rate.Grinding the lands of the teeth provides the leading edge of each tooth with the final sharpness required for maximum carding power.
    2. The first grinding should be allowed to continue until at least 80% (for cylinder) and 100% (for doffer) of the lands of the teeth have been ground sufficient to sharpen the leading edge of the tooth.
    3. To ascertain this stage of grinding, it is necessary to stop the cylinder regularly and use a simple microscope to examine the teeth at random across and round the cylinder.
    4. If the wire on the cylinder is of good quality and has been correctly mounted, the initial grinding period should be completed with in 20 min.
    5. It is essential to avoid over-working the wire before taking corrective action. The regrinding cycle must be determined accurately for the conditions applying in the individual mill, by using the microscope.
    6. If regrinding is done properly, there are several advantages
      1. carding quality will remain consistent
      2. There is no risk of overworking the wire
      3. Time required for regrinding is very short
      4. The exact condition of the clothing is known
      5. The working life of the wire is likely to be longer because the points are never allowed to become worn
        beyond recovery
    7. To obtain acceptable grinding conditions at the low grinding speed, the grindstone must always be SHARP, CLEAN and CONCENTRIC. If the grinding stone is gradually allowed to become dull and glazed
      through constant use, the limited cutting action available will eventually disappear, resulting in burning and hooking of the carding teeth.
    8. Due to the low peripheral speed of the grindstone which has to be used, it is most important that the speed of the wire to be ground is as high as is practicable to provide a high relative speed between
      the grindstone surface and the cardig teeth.If wire speed is low, the individual carding tooth spends too long a time in passing under the grindstone, thereby increasing the risk of hooking and burning the tooth, which is usually irreparable.
    9. With cylinder grinding, speed is no problem because the normal operating speed of the cylinder is more than sufficient. The speed of the doffer for grinding is more commonly a problem and this should be driven at a minimum speed of 250 m/min, to avoid damage when grinding the wire, the design which is particularly susceptible to hooking due to the long fine, low angled teeth needed on the doffer.
    10. The directions of rotation for metallic wire grinding are normally arranged so that the back edge of the tooth is first to pass u nder the grindstone. This is termed grinding “back of point”
  3. GRINDING FLAT TOPS:
    1. Flat tops provide the opposing carding force against the cylinder wire and hence can equally effect
      carding quality.It is essential to ensure that the tops are kept in good condition to maintain maximum
      carding power with the cylinder.Again, the only reliable approach is to examine the tops with the
      microscope and decide whether grinding is required or not.
    2. For cards fitted with regrindable tops, it is good practice to regrind the flats at regular intervals
      thus ensuring that the conditions of the two principal carding surfaces are always complementary one to other.

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