Showing posts with label Carding. Show all posts
Showing posts with label Carding. Show all posts
8 March 2013

Carding Setting Between Licker-in (Taker-in) to Cylinder, Cylinder to Flat and Cylinder to Doffer

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Speeds:
  1. Higher cylinder speed helps fiber transfer. Higher the production, higher should be the cylinder speed.
  2. Higher cylinder speed improves carding action, thereby imperfections are reduced.
  3. Higher Licker-in speed for coarse fibers and dirty cotton helps to remove the trash and improves,  the yarn quality. For fine and long cottons, higher speed results in fibre rupture, therefore, flat waste and comber noil will be more.
  4. Higher flat speed, improves yarn quality and at the same time increases the flat waste.
  5. With the same flat speed, higher the carding production, lower the flat waste and vice-versa.
  6. Very high tension drafts will affect carding U%. It is better to keep the draft between feed rollers to doffer around 75 to 95. The results are found better with these drafts. 
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8 November 2012

Carding Process | Setting of Carding Machine | Working Process of Licker-in, Cylinder, Doffer

Introduction:
Carding is the most important process in spinning. It contributes a lot to the yarn quality. The following process parameters and specifications are to be selected properly to produce a good quality yarn with a lower manufacturing cost cylinder wire(wire angle, height, thickness and population) flat tops specification licker-in wire specification doffer wire specification feed weight draft between feed roller and doffer cylinder grinding doffer grinding flat tops grinding cylinder, flat tops, doffer wire life Licker-in wire life Cylinder speed flat speed Licker-in speed setting between cylinder and flat tops setting between licker-in and feed plate setting between lickerin and under casing elements like, mote knife, combing segment etc. setting between cylinder and doffer setting between cylinder and back stationary flats setting between cylinder and front stationary flats setting between cylinder and cylinder under casing

Cylinder Wire and Cylinder Speed:
Cylinder wire selection is very important, it depends upon cylinder speed, the raw material
to be processed and the production rate. The following characteristics of cylinder wire should be considered.
 
1. wire angle
2. tooth depth
3. wire population
4. rib thickness
5. tooth profile
6. tooth pitch
7. tooth point
8. overall wire height

Wire front angle depends on mainly cylinder speed and coefficient of friction of raw material. Higher the cylinder speed, lower the angle for a given fibre. The cylinder speed in turn depends upon the production rate. Higher production means more working space for the fibre is required. It is the wire that keeps the fibre under its influence during carding operation. Therefore the space within the wire should also be more for higher production. Higher cylinder speed also increases the space for the fibre. Therefore higher cylinder speed is required for higher production. In the case of high production carding machines, the cylinder surface is very much higher, therefore even with higher number of fibres fed to the cylinder, the cylinder is renewing the carding surface at a faster rate. 
Higher the cylinder speed, higher the centrifugal force created by the cylinder, this tries to eject the fibre from the cylinder, along with the trash. It is the cylinder wire's front angle which overcomes the effect of this force. Low front angle with too low cylinder speed and with high frictional force will result in bad quality, because the fibre transfers from cylinder to doffer will be less. Hence recycling of fibres will take place, which result in more neps and entanglements. The new profile with less free blade avoids loading of the cylinder with fibre and/or trash. This helps in keeping the fibres at the tip of the tooth. The movement of the fibres towards the tip of the tooth coupled with centrifugal action demands an acute front angle to hold the fibre in place during carding. Lack of stiffness associated with fine and/or long fibres necessitates more control during the carding process. This control is obtained by selecting the tooth pitch, which gives the correct ratio of the number of teeth to the fibre length. Tooth pitch reduction is therefore required for exceptionally short fibres and those lack stiffness. Number of points across the carding machine is decided by the rib width. It is selected based on the production rate and fibre dimensions. Finer the fibre, finer the rib width. The trend is to finer rib width for higher production. 
The population of a wire is the product of the rib thickness and tooth pitch. The general rule is higher populations for higher production rates, but it depends upon the application. Sharp tooth points penetrate the fibre more easily and help to intensify the carding action. Cut-to-point wires are sharp and they have no land at all. The effective working depth of a cylinder wire tooth for cotton is approximately 0.2mm and for synthetic materials approx.0.4mm. Manmade fibres require more space in their cylinder wire than doe's cotton. More tooth depth allows the fibre to recycled, resulting in damaged fibres and neps. If tooth depth is insufficient, there will be loss of fibre control. This will result in even greater nep generation. Looking into the above details, the following specifications can be used as a guideline.
DOFFER, LICKER-IN AND FLAT TOPS:
  • The basic function of doffer is to strip the fibres from Cylinder. Please remember that the action between cylinder and doffer is carding action (or combing action or point to point action).
  • The doffer wire's front angle plays a very important role in releasing the fibre from the cylinder. For most carding applications the optimum angle is 60 degrees.
  • Increased population over 400 ppsi does not give any advantage in the production of quality yarn. For smaller doffers, 5 mm doffer wire height helps in transferring the fibres from cylinder to doffer.
  • If the fibre holding capacity of the doffer wire is less due to fibre friction or due to very high doffer speed, it is better to use a doffer wire with striations. For high production carding itis always better to use doffer wire with striations.
  • Licker-in plays a major role in opening the fibre tufts. In general 85 degrees is used both for synthetic and medium and long cottons. For coarse and dirty cottons 80 degrees can be used.
  • Strength, hardness and sharpness are very important for Lickerin wire. Licker-in wires should never be ground. Thinner blades penetrate the fibres more efficiently and increase the wire life.
  • Higher number of rows per inch gives better results. Now up to 12 rows per inch is being used. This is always better compared to 8 rows per inch.
  • · If the wire pitch is not sufficient, it can be compensated by increasing the licker-in speed. Higher licker-in speeds for fine and long cottons will rupture the fibres. Licker-in speed depends upon the fibre type and the production rate.
  • It is better to use a flat top with more than one population. The general combination is 280/450. This is suitable for both cotton and synthetics. Please remember that the rigidity of the fillets is different for cotton and synthetic. If cotton flat tops are used for synthetic processing, the load on the cylinder will be more, more heat will be produced and hence the probability of cylinder loading due to electrostatic charge will be high.
  • Instead of using Rigid type flat tops, it is better to use semirigid type flat tops while processing synthetic fibres.

SETTINGS:
  • The setting between cylinder and doffer is the closest setting in the card. This setting mainly depends upon the cylinder speed, hank of the delivered sliver and the type of wire. Cylinder speed up to 360, the setting should be 0.1mm. For cylinder speeds more than 450, the setting ranges from 0.125 to 0.15.
  • If the setting between cylinder and doffer is very close, the wires will get polished and this will affect the fibre transfer. If the setting is too wide, the fibres will not be transferred to doffer from the cylinder, hence cylinder will get loaded. While processing synthetic fibres cylinder loading will badly affect the yarn quality. Moreover, it is difficult to improve the wire condition if the loading is severe. The only solution would be to change the wire. Therefore enough care should be taken while processing synthetic fibres.
  • The most critical setting in a carding machine is between cylinder and flat tops. While processing cotton, it can be as close as 0.175 mm provided the mechanical accuracy of flat tops is good. Since most of the cards are with stationary flats at the licker-in side, the setting from the back to front for flats can be 0.25, 0.2.0.2, 0.2, 0.2mm.
  • Closer the setting between cylinder and flats, better the yarn quality. Neps are directly affected by this setting. Of course, very close setting increase the flat waste. For processing cotton the setting can be 0.25, 0.2, 0.2, 0.2, 0.2mm. For synthetic fibres it can be 0.3, 0.25, 0.25, 0.25, 0.25mm
  • Most of the cards are with 6 to 1 1 stationary flats at the licker-in side. This setting can start with 0.4 mm and end with 0.25mm.
  • The wire points can start with 140 ppsi and end with 320 ppsi. The work done by the first few stationary flats is very high; therefore the wear of these flats is also high. It would be better if the first 50% of the flats are changed after 100000 kgs of production and the rest after 150000 kgs of production.
  • These stationary flats open the material so that, the setting between cylinder and flats can be as close as possible.
  • The setting between feed plate and Licker-in depends upon the type of feed plate. Conventional feed plate setting is decided mainly by the feed weight and to some extent by the fibre length and type. With the latest feed plate and feed roller arrangements, the setting is decided mainly by the fibre length and to some extent by the feed weight.
  • Normally the setting between the feed plate and Lickr-in is around 0.45 to 0.7mm, depending upon the feed weight and fibre type.
  • The setting between Licker-in and the first mote knife is around 0.35 to 0.5 mm. This helps to remove the heavier trash particles and dust. Closer the setting, higher the wastage. The setting between Licker-in and combing segments is around 0.45 to 0.6. This helps to open the material.
  • Some cards have two mote knifes in the Licker-in under casing. The setting is around 0.4 to 0.5mm. This helps to remove the smaller trash and dust particles.
  • The setting between the cylinder and stationary flats at Doffer side helps to transfer the fibres to doffer by stripping the fibres to the top of the cylinder wire. This setting can be as close as 0.15mm. The number of wire points on stationary flats also plays a major role. It is normally around 300 to 400. For a high production application it can be as high as 600.
  • For cotton processing, the stationary flats are fixed with a knife attachment. The setting should be as close as possible, i.e. around 0.15mm. This helps to remove the trash particles of very small size.
  • The setting between cylinder and cylinder under casing should be as per the manufacturer's recommendation. The design of under casing is different for different manufacturers. This setting is very important, as wrong settings will affect the fibre transfer and can also create air turbulence.

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

WIRE MAINTENANCE:
  • For a modern cylinder wire of 2mm height, grinding with the normal grinding stone is not recommended. It is better to use TSG grinder to grind the wire every 2nd or 3rd month, so that the sharpness of the wire is always maintained.
  • TSG grinder does not grind the wire, therefore if the wire is worn out very badly the quality improvement using this grinding machine will be nil. Frequent grindings are recommended. If TSG grinder is not available, it is better not to grind 2mm wires.
  • The number of traverse should increase depending upon the life of the wire. The number of traverse for successive grindings should be like this 3, 5, 10, 17 etc. Anyway the best method is to confirm with the microscope. If the grinding is not sufficient, the number of traverse should be increased.
  • Doffer is still working with a concept of Land formation. A normal grinding machine will be good for doffer grinding. All the wire points should be touched by the grinding stone. A slow and gradual grinding with the grind-out concept will give the best results. Harsh grindings will result in burr formation on the land. This will increase the number of hooks in the fibre; thereby the effective length of the fibre from this card will be reduced.
  • Flat tops grinding is very important. Every time a flat top is ground, yarn quality is improved. It is better to use a grinding machine with the emery fillet. Frequent flat tops grinding will result in less neps and the yarn quality will be consistent.
  • Some mills increase the life of the flat tops compared to cylinder wire. But it is better to change flat tops and cylinder wire together for better and consistent yarn quality.
  • It is a good practice to check the individual card quality before changing the wire.
  • Licker-in wire should be changed for every 150000 kgs. Earlier changes will further improve the yarn quality.
  • Stationary flats should be changed for every 150000 kgs. But it is a good practice to change the first 3 or 6 stationary flats at Licker-in side for every 100000 kgs. This helps to maximize the carding effect between cylinder and doffer which is critical for better yarn quality.
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12 October 2012

Card Clothing | Flexible Card Clothing | Semi-rigid Card Clothing | Advantage of Flexible Card Clothing | Disadvantage of Flexible Card Clothing | Advantage of Semi-rigid Card Clothing

Card Clothing:  
The inclined wire set in base material which are covered around the surface of taker in. Cylinder, doffer and flat in the carding machine is called card clothing.

Card clothing is used on the surface of
  • Taker in;
  •  Cylinder;
  •  Doffer;
  •  Flat.
Flexible Clothing: 
These clothing have hook of round or oval wire which are set into elastic, multiple – ply cloth backings. Each hook is bent to a U-shape and is formed with a knee that flexes under bending load and return its original position when the load is removed.

Advantage of Flexible Card Clothing:
i. Point density being high, carding action is good.
ii. Wire point flexible so fibre damage is less.
iii. Fibre, yarn can produced.

Disadvantage of Flexible Card Clothing:
i. Carding angle cannot be choosen.
ii. Grinding action should be regular.
iii. Foundation material are required.

Semi Rigid Clothing:
In case semi-rigid clothing the sharp pointed wire are set in more rigid backings. This backing is made of multiple plies and the no of plies are more in number than that in flexible clothing. The wires have no knee & are deeply set inside the plies. The wire are much less capable yielding than flexible clothing.

Use: 
Semi-rigid clothing is found only in the flats.

Advantage of Semi-rigid Card Clothing:
  • No need of sharpening after short use.
  •  No dirt and dust in stored.
  •  No need to of frequent grinding.
  •  Grinding: It is process of retaining the original position of cloth wire after using for a long time.
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12 September 2012

Different Action in Carding | Carding Action | Stripping Action | Doffing Action

1. Carding Action:
When two close surfaces have opposite wire direction and their speed direction or relative motion is also opposite. Then the action between two surfaces is called carding action. 
Different Action in Carding
 

Function:

  • It is occurred between flats and cylinder.
  • Maximum individualization of fibers is achieved in this region.
  • Naps short fibers dirt and dust are removed by this action.
  • There always should be point against point action.
2. Stripping Action:  
When two close surfaces have same wire direction and their speed direction or relative motion is opposite then the action between two surfaces is called stripping action. 
Different Action in Carding  Function:
  • It is occurred between licker in and cylinder.
  • There are should be point against back action.
  • Individualization of fibre is also by this action.
3. Doffing Action:
When two close surfaces have opposite wire direction and their speed direction or relative motion is also opposite then the action between two is called doffing action

Function:
  • It is occurred between cylinder and doffer.
  • Web formation is accrued by this action.
  • There always should be point against point action. 
5 September 2012

Defects in Carding | Causes for Defects in Carding | Preventive Action in Carding Process.

Crding is a process in the manufacture of spun yarns whereby the staple is opened, cleaned,aligned, and formed into a continuous, untwisted strand called a sliver. A lot of defects occur during carding process. Defects or faults and their causes of carding are given below:
Defects in Carding:

  1. Sliver variation
  2. Cloudy web
  3. Hole in web
  4. High nep count
  5. Web slagging
  6. More cylinder loading
  7. Broken or malformed selvedge
  8. Excessive blowout
  9. Disappearing web
  10. Flat strip too heavy
  11. Taker-in snatch
  12. Loss in yarn strength
Causes for Defects in Carding
Important causes for defects in carding are mentioned below: 

Causes for Neps Formation
  • Insufficient stripping
  • Dirty under casing ( grid bar)
  • Uneven flats setting
  • Under casing chocked with fly ( waste)
  • High roller speed
Causes for Holes or Patches in Card Web
  • Poor flat stripping
  • Hooked or damaged wires on flats
  • Damaged cylinder
  • Cluster of cotton embedded on cylinder wires
Preventive Action in Carding Process
In order to avoid sliver variation draft calculation should be correct. Testing of sliver must be on time at least 3 times during shift.

High sliver variation problem may also be due to maintenance problem. So concentrate on maintenance. If our maintenance of machine will be there, then it will get more efficiency and better quality will be achieved. If expiry time of some part of the machine is there, then on time it must be replaced.

Now a days in advance technology the cards, auto leveler are electronic which adjust thesliver weight automatically. For getting better result with automatic auto leveler, it is also necessary to check sliver weight manually as well.

Preventive Action for Nep Formation
Over hauling of machine must be on time. During over hauling, setting of every part of the machine has to be checked. Flat setting play very important role for reducing nep formation. So flat setting must not be uneven.

Suction waste point should be properly working. This point must not be chocked. If there will be chock then neps formation will take place. Suction waste point also to be checked manually as well.

This problem is also related to maintenance. Over hauling of every machine must be on time. Wire of flats and cylinder have specific time limit of production. After that specific time limit it must be changed. As these play very important role by quality point of view. 

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10 May 2012

Carding Machine | Carding Process | Object/Task of the Carding | Action in Carding Machine

The card is the machine which is used for carding. In the card we put lap from blow room and after carding we get carded sliver. This is second stage machine operation in conventional spinning line. Carding may be defined as the reduction of an entangled ways of fibers to a filmy web by working between surfaces clothed with shirp wire point.

The proverbs of the experts ” The card is the heart of the spinning mill and well carded is half spun demonstrate the immense significance of carding for the final result of spinning operation." The importance of carding is still greater where new spinning system are concerned.

 Object or Task of the card:

Opening to individual fibres:  
The blow room only opens the raw material to flocks where as the card opens it to the stage of individual fibres. This enables the eliminations of impurities and good performance of the other operation.

Elimination of impurities: 
Impurities are mostly eliminated in taker in and a small portion of it is eliminated by flat stripping. Modern card removes 80 – 90% impurities from lap and sliver contain only 0.05 – 0.3% foreign matter.

Elimination of dust:  
Card is good dust removing machine. I t removes free dust as well micro particles by significant friction.

Disentangling of neps:  
Blow room increase neps from machine to machine, but card reduce it to a small friction. The card does not remove neps but disentangles it by opening them. Closer spacing between the clothing, sharper clothings optional speed of taker in, low doffer speed etc. Can improre the disentangling process of neps.

Fibre blending:  
The card scarcely improve long term blending as the residence time of the material in the machine is to short. The card improves traverse blending and fibre with fibre mixing.

Action in Carding Machine: 
The following 4 actions take place in a carding machine:
1. Combing action;
2. Carding action;
3. Stripping action;
4. Doffing action.

1. Combing action:  
Combing action takes place feed roller and taker in. Here the pin direction of the two surfaces are the same. Combing is the straightening and paralleling of fibre and the removal of short fibres and impurities by using a comb or combs which is assisted by roller and brushed.

2. Carding action:
Carding action takes place between flat and cylindex.
In carding action:
  •  Direction of wire in two surfaces are opposite.
  • The moving direction of roller are also opposite.
  •  One roller is slower and other is fast.
So carding action is known as point against point action.

3. Stripping action:  
Stripping action takes place between a. Taker in & Cylinder and b. Doffer & Stripper.
In stripping action:
  • Wire direction will be the same.
  •  Roller moving direction will be the same.
  •  One roller will be faster than another.
So stripping action is known as “Point back point” action.

4. Doffing action:  
This action take place between cylinder and doffer. In this place fibre is transferred from cylinder to doffer. Low speed doffer is called fibre from high speed cylinder and make a condensed web for formation of sliver.

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15 December 2011

Cotton Carding Process | Working Process of Cotton Carding

Carding
Carding is one of the most important operations in the spinning process as it directly determines the final features of the yarn, above all as far as the content of neps and husks are concerned. There are many objectives of the carding process and these can be summarised as:
  • Opening the tufts into individual fibres;  
  • Eliminating all the impurities contained in the fibre that were not eliminated in the previous cleaning operations;  
  • Selecting the fibres on the basis of length, removing the shortest ones; 
  • Removal of neps; 
  • Parallelising and stretching of the fibre; 
  • Transformation of the lap into a sliver, therefore into a regular mass of untwisted fibre.
Fig.A Section view of the card with hopper
The carding operation is carried out by the card, a machine that in practice is a system of rotating organs, mobile and fixed flats, covered with steel spikes that go by the name of wiring. It is a good idea to know what the wiring and its functions are before going onto a description of the card.

Wiring and Clothing 
There are different types of cylinder wiring, in particular:
  • rigid wiring, for rotating parts; 
  • elastic clothing, for mobile flats;  
  • clothing for fixed flats.
The most common on the machine are the wiring type. They are made up of a steel wire with sharp cutting teeth, the sawtooth like edge of the wiring is hardened in order to better resist wear caused by the abrasive action of the fibres. The base of the wiring is thicker than the toothed parts, both to guarantee support to keep the teeth in a vertical position, as well as to prevent lateral contact between the teeth and to permit the necessary momentary penetration of fibre into the wiring.

The sizes of the teeth vary notably and depend on how compact the material is, on the quantity and on the fineness of the fibre. The parameters which permit one type of wiring to be distinguished from another are: 
Concentration, meaning the number of teeth in a square inch of the wiring (for the various devices of the card the concentration is different and is strictly linked to the type of fibre used; for fine fibre, for example, wiring with a high concentration is used);
  • The height of the teeth, which can vary according to the wired element;  
  • The angle between the teeth and the base in a longitudinal sense.
It is a known fact that a wired element moves in:
  • a positive way when it moves in the same direction as the inclination of the teeth; 
  •  a negative way when it moves in the opposite direction to the inclination of the teeth
The fibrous material is found between the two wired elements which, by moving, act on the fibre in an alternate manner: first they trap it then they remove it. Depending on the layout of the teeth, the direction travelled and the speed of the devices, two conditions are possible, called:
  1. Carding position which is obtained when the teeth of the wired elements are inclined in an opposite direction and their movement occurs with a certain speed and in a direction that permits a reciprocal grasp of the fibre and then the disentangling of the neps and elimination of trash and dust.
  2. Position of cleaning or brushing , which is obtained, on the other hand, when the devices have converging teeth and their movement occurs with such a speed and in such a direction to permit the passing of fibre from one organ to another.
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