Tandem carding | How it works?

Limitations of single carding process are: 1 In a single carding process, when a thick sheet of flocks and tufts are fed, overloading of some areas of the cylinder surface and of the flats cannot be avoided with the result that wire points fails to control and card the fibres effectively.

When the skins and seeds are crushed by the purifying rollers or crush roller in High production cards, the liberated fibres remain entangled and unopened in the web as small fiber agglomerations resulted in uneven yarn appearance.

The levelling function of a single cylinder and doffer is not sufficient to completely eliminate the uneven distribution present in the carded web.

Tandem carding system is essentially a double processing of the web to eliminate the limitations in a single carding process. The tandem carding system has two high production cards linked together so that the second card is able to do a fine job of separating every fibre as well as removing the crushed impurities passed on by the first card namely breaker card. 

Principle and passage of material through Tandem carding:

After first carding, the stripping roller remove the web from doffer.

From stripping roller the web is stripped by the redirecting roller which assist in controlling the feeding of the web into the nip of the web purifying roller(pressure roller or crush roll)

From nip of the pressure roller the web comes under control of two transfer roller, which carry the web over the top so that the quality of the web produced by the breaker card is exposed for inspection.

The web now passes through finisher card which receives a fine film of fibres instead of flocks.

The tangled tuft of fibres still present after breaker carding which causes variations, is further reduced by extra carding action of the finisher card.

Any impurities, which protected by the thick fibre layer when passed through first pair of web purifying roller, is crushed and eliminated in the India roll unit mounted at the end of the finisher card.

Advantages:

Improvements of yarn qualities:

Increase of 3% CSP

Improvements in U %

Reduction of 50% neps;

Reduction pf 20 % Thick thin place:

Reduction of 35%end breaks in ring spinning.

Upgrading: No single card can match the Tandem's ability to produce high quality yarn from low grade cotton.

In open-end spinning, the operating efficiency is improved by unmatched degree of trash removal & fibre individualization achieved in tandem card.

Economy in combing process:

ft reduction of 3 to 5 % waste at combing will still yield yarn
of equal quality.

Waste blends:

Tandem card can operate at high speed with ultra short staple blends of waste fibre etc, which may be impossible to process on single cards.

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High Production card and conversion of conventional card into High Production card

Explain in detail how you will convert conventional card into High production card or what are the advantages of HP card: what are the special features of HP card & how these features improve productivity and quality Discuss the development that have taken place in carding.

SPECIAL FEATURES OF HIGH PRODUCTION CARD

Following alterations and additions have been made to conventional card, to convert the conventional card into HP card.

Rigid wire clothing known as Metallic wire clothing on cylinder and doffer gives the following advantages.

No frequent grinding & stripping

Saving of good fibres

No neps formation due to better wire condition

less variation in card sliver owing to reduced stripping cycle

Card can run at high speed due to rigid foundation of clothing.

Dynamically Balanced cylinder and doffer helps to achieve close setting and run the card at high speed.

Steel shaft with ball bearing to cylinder & Roller bearing to doffer(instead of cast iron shaft with plain bearing) for extra load of about 150 kg due to metallic clothing.

Rigid, well braced cast iron frames are provided with levelling screw to over come the problem like vibration, fly generation, due to High speed of HP card.

Changing of Existing licker-in under casing to a shirley type or by providing fibre retriever or by providing the comb bar with waste control knife attachment, below the licker in, the following advantages are claimed:

Opening of tuft at high rate of feed is improved

Tufts are distributed as evenly as possible on the cylinder.

Maximum trash extraction with minimum loss of spinnable fibres.

* Viking 200 Precarding segment (64 mm width & 60 points/sq inch) mounted on licker-in side of the cylinder open and card the fibres effectively and allow the flats to be set closer.

* Viking 400 Post carding segment (4 teeth segment with 128 mm width and 150 points/sq inch) mounted on the doffer side of cylinder produce remarkable improvement in yarn quality.

* Evener Roller placed in between cylinder and licker-in at the top, open the large unopened tufts and remove excess fibre on cylinder, and return to the feed Roller again.

* Comb bar- clothed with coarse pitch wire (instead of moteknife) positioned under the feed plate nose, improve the opening and give a pre carding action and gives high trash yield by permitting the trash to separate from the main stream of fibres in the large free space following the comb bar.

* Card cylinder is either made of thick sheet metal sufficiently reinforced and annealed or by special cast iron stabilised, rectified and reinforced by ribbed structure to withstand the stress & strain at high speed of cylinder like 600 PPM.

Many machinery makers has developed stationary flats in place of revolving flats in order to reduce the flat waste and provide maximum carding area and improve the carding quality.

Roller Doffing device in Hp card gives the following advantages

i) Smooth auto doffing at any speed of doffer with absolute web control, 3 to 5 times more production than con-card,

ii) Improved yarn quality by reduction of impurities and neps.

* By providing the latest flat top clothing like/Supra Top or
Rappo Top diamant top, & regid strato top metallic flat clothing,
the following advantages are claimed.

i) Intensive caring. ii) fibre protection, lii) Removal of more short fibres without increasing the amount of waste. iv) High stability suitable for higher production
v) Minimum flat waste, iv) No loading with fibres.

* Electronically controlled Auto leveller in the HP card continuously check the sliver weight and automatically correct the sliver variation and improve sliver and yarn evenness.

* Stop Motion in the feed Roll protect the feed roll and wire points of licker-in from damage due to metal part or thick place in feed. Also stop motion with signal light in calender Roller, coiler hood and coiler unit, stop the card whenever sliver is missing or too thick or thin sliver or chocking in coiler. Changing the coiler head bigger can (24" * 48 ")

Cross apron web doffing system effectively doff and control the web from crosrol unit.

Doffer slow motion drive facilitates the piecing up operation and eliminate the excess waste, during piecing work.

The shirly pressure point system and improved waste suction in card, reduces the dust load in the card room atmosphere by about 90%

Changing the coiler head to work bigger size can (24 inch dia, 48 inch ht) and accommodate more length of sliver and reduce the piecing and improve the efficiency of next machine

Peed region is adjusted for accommodating bigger size laps.

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Doffing System in carding machine | How it works?

officina Meccanica Montenero of Italy has exhibited a fly comb with motion boxes fitted on both sides to achieve 3000 strokes per minute without vibration. Further the comb shaft is made of special alloy of having 50 per cent reduction in weight. This reduction of 50 percent of reduced weight, resulted in less wear and tear of parts, low vibration and energy consumption.

Roller doffing device

Increase of speeds of licker-in, cyliner and doffer for achieving higher production rate, demands corresponding increase of doffer comb speed to avoid the loading of fibres on the doffer.

But the doffer comb fails to remove the fibres from doffer when the speed exceeds 16 RPM. Therefore many doffing devices have been developed to cope up with high production.

Roller doffing devices are of the wing two types.
1. crossrollvarga 2. India rolvarga Roller doffing device.

crosrol varga unit

India rol varga unit.

one set of stripping roller and pair of crush roll unit is provided.

Two sets of stripping roll &

pair of crush roll units are linked together so that the IInd set of crush roll is able to do a fine purification of web.

Crosrolvarga and India Rolvarga Roller doffing device

Stripping roller strip the web from the doffer under positive control at any production rate. The web is removed from the stripper by redirecting Roller.

Both the stripping and Redirecting Roller are covered with a specially designed Metallic wires.

Now, the web is carried into the nip of the pair of polished crush rolls or pressure roller or web purifying roller.

The pressure Roller crush the impurities and extract the if rash from the web and apply draft to the web.

Total draft applied between the doffer and calender roller is app. 1. 4

This draft parallelizes the fibres giving better exposure of trash to the crushing action.

This amount of pressure applied by the crush roll can be varied according to the quality of cotton being processed and rate of production of card.

Both top and bottom crushing rollers are provided with adjustable & replaceable steel scraper blade which removes dust particles, impurities and seed bits from the crushing roll.

A spiral groove cut into the surface of each crosrol prevents the accumulation of fly under the blade.

For synthetic fibre-plain crush roll with nylon blade. is used & should not be given any pressure.

For coarser sliver - crush Roll pressure has to be increased.

From the crushroll, the web coming out is collected and

condensed by the apron web doffing device and passed through trumpet and calender Roller.

In India Rol varga unit, There is no redirecting roller web from 1st stripping roll is carried into the nip of 1st set of crush roll directly, a second stripping roller collects the web from the 1st set of crush roller.

From 2nd stripping roll the web is now carried into the nip of the pair of 2nd set of crush roller.

Any impurities, which may have been protected by the thick fibre layer when it is passed through the first pair of crush roller now, have the chance to be crushed and eliminated by the 2nd set of crush roll. Then only the web is condensed and passed through the trumpet & calender Roll.

Calender Rollers are mounted on ball bearing and top calender roll is provided with spring weighting.

Sliver break stop motion is incorporated in the calender Roller unit.

Advantages of Roller Doffing Unit.

Smooth auto doffing at any speed of doffer with absolute web control

Improved yarn quality by the reduction of impurities.

3 to 5 times more production than conventional card.

Consistent doffer speed which enables uniform production rate.

Upgrading of dirty cotton by ironing the web.

Higher efficiency and reduction of end breaks at spinning frame.

Setting points in India Rol unit:

Cylinder to doffer 0. 004 "

Doffer to stripping roller 0. 005"

Stripping roller to crush roller 0. 032"

Crush rol to 2nd stripping roller 0. 022"

2nd Stripping roller to second crush Roller"

Apron web doffing device

Apron web doffing device is used for effective controlling and doffing the web which is delivered from crush roller of roller doffing unit of HP card i. e., the web delivered from the crush roller is gathered by the cross apron as shown and condensed to form a sliver. It helps to cope up with very high delivery speeds like 300 metre per minute.

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Production and waste control in Carding Machine

Doffer speed should be maintained as constant and arrange schedule for checking the same daily.

Fluctuation in power, belt slippage, should be avoided and there should be effective power transmission without any slip.

Apron web doffing should be provided for the effective doffing of web.

Stop motion should be provided to eliminate excess waste and maintain the production as constant.

Auto leveller not only maintain the evenness of the sliver, also maintain the production as constant.

Doffer slow motion drive should be provided to facilitate the piecing operation & eliminate excess waste.

To doff the web effectively from doffer, roller doffing device should be used to maintain the production rate. Also, coiler doffing helps to get consistent doffer speed which enable uniform production Rate. Different types of waste and waste control in card Mote waste: The angle of mote knives may range from

vertical disposition to about 30 to the vertical, but the nearer a knife approaches a tangential position. the greater is the extraction of waste. If the setting is too close, loss of good cotton may occur and it is too wide, the mote knives operate inefficiently.

Under casing waste: Cylinder under casing to cylinder setting influences air currents and prodution of fly and too wider setting causes loss of fibres. similarly, lickerin to cylinder under casing setting if more, loss of fibre may occur.

Closer setting of takerin to takerin grid, increases the fibre extraction with waste.

Too close setting of feed plate with takerin, damage the longer fibres and waste is increased.

flat Strips waste: Front top percentage plate control the flat strips waste, this strips waste ranges about 2. 5 % of the weight fed, depending upon the grade of cotton, card setting and metallic wire clothing condition of the cylinder. Flat strips has a fair market value.

Wider setting of top % plate of front plate with cylinder, Increases the flat strips waste.

The speed of the flat is also directly related to the amount of waste removed in the form of flat strips, i. e, the higher the flat speed heavier is the flat strips.

If the flat strips represents the greater loss, they are an important factor in the cost of making card sliver. Other wastes:

Lap end waste from full lap before they are fed to the running carding-Improved transport methods and increasing the lap diameter together with strict supervision, can bring down this waste.

Carding is very much sensitive to temperature and humidity condition which require to be maintained in every shift, otherwise rich web and sliver waste is created.

Bigger card cans and box-type springs do help in the reduction of sliver waste at draw frame.

Too narrow trumpet guide before the calender roller create web waste.

The pressure between cros rolls require to be checked up and regulated according to the material, weather condition as these rolls also become a source of wastages at the card.

Overfilling of card can should be totally discouraged. General practice is to over fill and after doffing from the card, turn the top layers of the coils inside the can to prevent swelling this tends to spoil sliver evenness and create breaks and waste at later stage.

Standard card waste % for semi-High production cards for given trash content in the lap:

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Carding | Maintenance program

From the point of view of maintaining, good yarn quality, carding is the most important process in spinning care should be taken to ensure high standard of maintenance in carding.

Preventive Maintenance means to check the machine regularly and defects are discovered and remedied before they cause a need for a major repair.

CHECKLIST FOR PREVENTIVE MAINTENANCE

Parts to be inspected(Once in	Rating &              Action taken/
15 days)	Remarks          Repaired/Replaced
* Feed Roller ends and bush	If the part is defective
conditions for wear.	write poor and needs.
* Examine licker-in, cylinder &	Correction in rating column
doffer wire for bent, blunt and	and the parts that are
broken wire.	replaced or repaired.
* Examine under grids for dents, broken grid & joints for soldering.	Will be entered by maintenance in charge.
* Check all the card settings.
* Check flat comb and Brush.
* Check crosrol pressure and

scrapper blade condition.

Check   the condition of all the condensing zone   and   coiler parts.

Check the stop motion and safety devices

Check flat chain tension.

Check feed Roll/Lap roll rotation for any intermittent rotation.

Check for side shaft eccentric

Check for cleanliness of card.

Ensure material handling equipment. and their condition and Availability.

check the sharpness of moteknife.

Lubrication system

condition of all bearings.

condition of all gear / stud/ chain / belt drives.

Check for Roller vibration/Eccentricity.

Check the speed of the all rotating organs.

Check the condition of auto leveller.

 

Routine   Maintenance:

As per maintenance schedule, works    are carried   out as per schedule so as to maintain the   M/C   imperfect  condition with minimum wear and tear.

Nature of operation                                               Frequency
General  cleaning                                                 15 days
Half settings (Dismantling and cleaning of licker-in, feed plate, setting of flats to cylinder, cylinder to doffer, cylinder                       15 days to under grid)
FULL SETTINGS: In addition to half setting jobs, Dismantling & cleaning of cylinder under grid, Back &   front plate, Cleaning of Roller doffing unit, apron doffing unit, stop motion checking, complete resetting                            1 month SI card)
petrol cleaning of cylinder and doffer
wire to remove wax and micro dust	2 month
Grinding the cylinder, doffer wire	6 month
Grinding of flat wire (ICCO 300, 400 type)	6 month
Burnishing of flat wire (ECC0, Rappo type)	1 month
(Grinding - need not be necessary )
Stripping the cylinder & doffer wire	Daily
Metallic wire Reclothing	3 years
flat chain changing	4 years.
Removal of fluff deposits on m/c with brush
Removal of waste under the under casings	Every shift

 

Shirley Nep counting:

 The template consists a 32 number of hole or cells. Take a web samples in a template and count the no   of neps in each cell.

n= (1. 531 - log(34 - x) x 100)/ 0. 434 Where, n = Neps per 100 sg. inches of web.

 x=No. of cells containing neps. Nep   count  (N)   is defined as the number of neps   per    100    sq. inches   of card web forming a standard hank sliver of 0. 12   on   a card 40 inches wide.

ie., N = n x (Sliver bank/0. 12) x (card width in inches/40)

 

NO. of cells with Neps ( for example)	1	4	10	15	20	25	32
Neps/100 sq. in	3	12	35	58	89	133	280

Nep Rating, according to Neps/100 sq inches: 1-15 Low neps, 16-25 Average: 26 -40 High: over 40: very high neps formation. Web count Ratings: 10 to 15 Good: 20-25 Average: above 30 - poor.

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Fibre hooks in carding and their effects on yarn quality.

Write short notes on Hook fibres in carding Discuss why always a leading hook should be presented to the comber?

Give the percentage of leading and trailing hook in card sliver

What are the different types of hooks formed in a card?

Give their proportion of formation Following are the two types of hooks present in card sliver:

1. Trailing hook. 2. Leading hook.

The bulk of fibres as they leave the doffer are found to have hook at their rear end (back end) are 'Trailing Hooks" and the fibres are found to be hooked at their forward ends termed 'leading hooks'.

Proportion of the fibre hooks in the card sliver
Trailing hooks = 55 % Both ends hooked = 15%
Leading hooks = 15 % No hooks =15 %

Machine vibration, improper settings, and disturbing air current in the drafting zone have adverse effects and fresh hooks tend to appear. Hook formation tendency is proportional to the length as well as fineness characteristic.

Due to the natural reversal of material at each stage of processing, the hooks can be fed either as leading or trailing.

Major hooks as leading hook should be presented to comber, otherwise trailing hook increases the waste percentage at comber. The increase in waste is not because of the comber extracting more short fibre, but because of hooked long staple fibre go into waste.

Even number of passages (two or four machines) should be provided between carding and comber for presenting major hooks as leading to the comber. Similarly,

Odd number of passages should be provided between card & Ring frame to feed major hook as Trailing hook, to the Ring frame.

Effect of cylinder speed on hook formation and yarn quality. Count 44s; Doffer = 7 RPM. 50 grains/yard of sliver.

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Dust extraction systems in Carding

The high pressure area in the card-at the junction between cylinder and flats at taken-in end-causes ejection of dust over top of the back plate and between the flats.

Another high pressure area- at the junction between the main cylinder and doffer -leads to ejection of dusty air over the doffer

Doffer comb produces air turbulences, which causes dust to rise and at the calender roller the air that is mixed with the cotton in the web is squeezed out, together with dust and fly.

Air escaping into the atmosphere from the high pressure zone carries dust with it and is responsible for most of the dust in the card room.

Modern HP cards are equipped with the dust and fly collector such as shirley pressure point system for extracting the dust, fly and fibres which are collected in a special chamber without rendering unhygienic the atmosphere in the card room.

This has low running cost and useful

1) to prevent the ejection of dust by suitably covering the regions of the machine where the dust is liberated.

2. To move the dust from several forces to a central region from which it can be conveniently removed.

An Exhaust fan, through suitable hoods fitted to critical regions of the card draw off air with fly and dust and after separating these from air, pure air is returned to the department.

The dust passing through the slits between the flats is retained (and then exhausted) by a flexible metal sheet across the full width of flats and placed inside the flat chain to cover about 2/3 of the flats

The region where flats take position on the bend is also boxed in and exhausted.

A deflector shield is fitted over the doffer comb and extends forward to the calender roller and the region under the calender roll is boxed in to collect the fly that falls from the under side of web.

A screen of perforated metal is fixed in front of the flat cleaning brush to catch any fly released there, and a similar screen is fitted on the coiler where the sliver turns through a right angle to proceed to the can.

The complete shirley pressure point system reduces the dust load in the card room atmosphere by about 90%.

Following are the improved waste removal system of latest high production carding,

Internal suction system:

The integral fan for internal suction creates a vacuum with in the outer shell. Thus no dust from the card escapes into. the workroom. the suction is very effective in the removal or fly waste, dust and micro dust which are released during carding. Dust and wastes are removed at all points of occurence, feed, flat entry, flar strips, web delivery and waste chamber under the card. The internal suction operates continuously there by maintaining constant autodymanic conditions in the card. 

The exhaust air is conveyed to air conditioning system. The amount of exhaust air is 2300 m3/h per card. Under card waste removal system.: . The under card waste are transferred by programmed periodic blasts of compressed air into the vicinity of a suction hood and collected in the rear most filter of the two filters built into the outer shell. The over card wastes including flat strips are collected in the foremost filter. The intermittently acting central suction system programmed to empty first the foremost filter and then the rear most filter.

The card can be connected to a continuously acting suction system in which case there is no need for fan and filters. manual cleaning of filter is necessary in the absence of central suction system.

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Developments in licker-in section of Carding Machine

Automation, higher production and improved quality of the products are the requisite of any recent developments.

Chute feeding is a recent development in feeding small tufts of cotton fibres directly from blow room to a series of cards, arranged in a circuit through ducts and chutes.

Already we have seen the working of chute feeding system in a third unit..

In this unit, we shall discuss some other developments in licker-in section of carding one by one in the following pages.

The objects of major developments in licker in section that have taken place are

To improve the opening of tuft at high rate of feed in H. P card.

To distribute the tufts as evenly as possible on the cylinder.

To extract the maximum trash with minimum loss of spinnable fibres.

Following are the developments that have taken place in the licker-in section.

1. Card analyser

2. Development in place of mote knife

3. shirley modification.

4. Fibre retriever.

Card analyser or uni opener.

M/S. Nagoya a leading card clothing manufacturer of Japan has offered an evener roller under the trade name of card Analyser. This may also be called as uniopener.

As shown in fig, this evener roller is placed above the licker in. It opens the large unopened tufts released by the licker-in and also remove the excess fibres on the cylinder which is returned to the feed roller again through a space provided between the taker-in and its cover.

Thus it helps to feed the tufts as evenly as possible on the cylinder. It is claimed that the neps formation and the waste are reduced.

Development in place of mote knife

M/S. Mafatlal Engineering has introduced comb bar and wast control knife attachment in their super card in place of mot knives, as shown in fig.

The arrangement consists of a small diameter cylinder clothed with coarse pitch wire. It replaces conventional mote knives when processing cotton and is positioned directly under the feed plate nose so that the material feed is immediately subjected to carding action.

This opens the cotton and gives high trash yield by permitting the trash to separate from the main stream of fibre in the large free space following the comb bar.

Shirley modification

The essential changes in the cleaning region are: 1. The replacement of conventional mote knives by a deflector plate which is provided under side of the feed plate.

The taker-in grid is replaced by a shorter grid usually 7" long, incorporating 3 bars and the normal perforations. & The Setting between grid and taker-in is made wider than the conventional card.

A safety guard is fitted under the feed plate to cover the exposed portion of the taker-in.

For short staple cotton 8" grid is usually suitable, for medium 7" grid and for long staple cotton 6" grid may be employed.

Advantages of shirley modification:

The amount of trash passed on to the cylinder was 31% less than normal resulted in cleaner sliver.

The dust generated during carding -is reduced.

The life of the metallic clothing is increased due to less trash on cylinder.

Increases the trash extraction of 10% with 24% less lint loss than conventional card.

Fibre retriver

This arrangement reduce the loss of spinnable fibres.

The nose of the fibre retriever deflects the heavier trash particles, downwards away from the licker-in.

Air drawn in by the fast rotating licker-in is channelled between the buffle plates of fibre retriever, so that the trash particles fall downwards in the up current of air, which detaches any spinnable fibre entangled with the trash particles and carries the good fibres back to the licker-in.

It is claimed that as much as 1 % waste is reduced.

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Developments in carding section

The important developments can be conveniently studied under the following heads:

Improvements in the cylinder construction.

Cylinder in high production cards must be capable of withstanding the stress and strain at speeds like 600 rpm.

The present day cards are either made of thick sheet metal sufficiently reinforced and annealed at low tension or by special cast iron stabilised, rectified and reinforced.

All the cylinders are provided with ball bearings and dynamically balanced so that accurate settings can be achieved.

In the cros Rolvarga MK 4 card, dia. of cylinder is 20 % smaller than the conventional cards to add stability and strength to cylinder and permit the cylinder rotates upto three times faster than the conventionally constructed cards. This also improves dust ejection and carding effectiveness for high quality sliver.

Developments in cylinder-flat zone:

The two major developments aimed at this zone are

1) To increase the effectiveness of flats

2) To reduce the flat waste

The important innovation is running the flats in the opposite direction to the cylinder as developed by SACM, FRANCE.

The following advantages are claimed due to change of direction of flats.

Thoroughly stripped, clean flats start their action at the delivery and of the cylinder. In this way the fibres are submitted to progressively cleaner flats, the final carding being performed by flats that have just been stripped. This results is more efficient carding than with flats loaded with wastes.

On the other hand the choke of the fibres against the flats encountered is dumped by the waste already collected by those flats. The large impurities contained in the web are retained by the first flats at the moment where they complete their carding cycle and just before being stripped. These impurities are therefore immediately removed and will not cling to the flats during the whole carding cycle with a risk of being taken up again by the cylinder.

Card Master:

M/s John Hollingsworth on wheels of Greenville has developed stationary carding plates in place of revolving flats under the trade name of CARD Master.

This consists of four strong, stationary aluminium plates with special metallic clothing applied to the inside surface. These plates, contoured to the shape of the cylinder, provide greater carding surface than revolving flats. The advantages claimed are

i) The weight of the card is reduced maintenance due to lock of moving parts.

ii) There is a power saving of 4%

iii) No flat waste

iv) provides maximum carding area.

v) Improves carding quality

vi) Long life since they can be re-ground.

4. Development in cylinder front zone:

i) viking 400:

It is the post carding segment to improve the parallalisation
of fibres. This is mounted on the doffer side of cylinder. It
consists of 4 teeth segments with a total width of 128 mm and a
teeth density of 150 points/sq inch. It produces remarkable
improvement in yarn quality.

ii). Trash master:

This is a system for the removal of vegetable matter, pepper trash, short fly, sticky particles, micro dust and : fused man made fibres. A special knife is set to the cylinder wire according the fibres to be processed. This knife, together with the centrifugal force and controlled air-currents, eliminate the trash. The extracted particles are collected in the low pressure chamber and removed the continuous suction cleaning.

It requires 165m3 air or 2 millibar low pressure, can be connected to all suction cleaning systems of high production cards.

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Auto leveler (autoleveller) in carding | How it works?

Careful control of sliver uniformity is necessary in the spinning process, to minimise the production of streaky fabrics. waste of raw material and  waste of production time.

So, continuous checking of sliver weight together with automatic correction of sliver weight variation at card is necessary.

The irregularity of card feed material is the important reason for sliver count variation ranging from very short(upto 25 cm) to very long term (more than 250 m ) variations.

Based on high spinning draft, even short term sliver irregularity leads to quite distinct count variation in yarn.

1. Graf 'Optima" card auto leveller:

Sliver passes between front draft controlling roller first, then passes between tongue and groove roller. Sliver variation cause the tongue (upper) roll to rise or fall. These very small movements of the tongue roll or the variations in mass per unit length of card sliver are amplified 20 fold and transmitted to an infinitely variable speed gear box. The out put shaft of the same drive the front draft controlling roller, calender roller, and coiler roller at variable speed so as to adjust the draft in accordance with the sliver thickness measurement.

2. RIETER C4 RR LEVELLER:

This system reduce long-term and short term variation., The weight of sliver leaving the card is sensed with a pair of stepped roll i. e., the number of fibres in the cross section is measured.

Deviations from the nominal count are processed by electronics into correction commands, which are executed at the card in take via the feed roll. 

3. INGOLSTADT ELECTRONIC LEVELLER

Of the two sensing roller, one is movable under spring pressure. The distance between centre of two rollers varies with the fluctuating sliver thickness. The amount of this lift is measured and converted into a voltage proportional to the sliver thickness.

Prom this measured value a set point speed is derived for the variable speed motor which drive the draft roll. If the actual speed differs from the set point, the variable speed motor is de-accelerated or accelerated untill the two speeds coinside i. e The output shaft of variable speed motor drive the draft roll at variable speed so as to adjust the draft in accordance with the sliver thickness measurement.

Stop motions in the carding

Stop motions are used in the following places of HP cards.

object:

1.To stop the doffer when sliver is missing or sliver is too thin or too thick or when the lap-up (choking) on coiler calender Roller.

If a sliver is missing or sliver is too thick/thin, the spacing between coiler calender roller changes. As the calender roll move, the aluminium disc is lifted and comes in contact with adjustable pins, it operate the corresponding electro pneumatic valve on or off the doffer driving mechanism.

2. Sliver break stop motion:

The sliver delivered from the calender roller passes beneath a guide located at the end of a lever. This lever drops when the sliver or the web breaks and, stop the card by the operation of the mechanism.

3. Coiler hood stop motion:

A limit switch is provided to prevent the starting of doffer when the coiler hood is opened.

4.Optical feeler in the coiler unit:

A photo cell monitors the sliver between the calender rollers and the coiler. The optical feeler is so arranged that the running sliver interrupts the beam of light and if the sliver breaks. light reaches the photo cell so the doffer drive is cut out and the fault signalling lamp lights up.

5. Peed Roller Stop Motion.

At both ends of the feed roller, microswitch is provided. During the entry of abonormal thickness of lap or metal pieces under the feed roll, the knob raises. When the knob raises by 1 mm the limit switch will act in such a way that the machine stop, and the white lamp burns, giving a signal to the operators.

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What are the Special features of modern beater in Blowroom?

What are the important features of the modern beater which make them suitable to process different varieties of cotton? Briefly explain them by taking example of a modern beater.

The latest approach is to open and agitate the cotton and remove the micro dust as and when generated before they settle down again.

In all modern beaters (like mono cylinder, Improved porcupine beater, ERM cleaner etc. , the grids can be adjusted individually. The grid can be adopted to handle any degree of impurity and opening in the cotton to be processed by means of the lever provided with scales.

The grid can be adjusted regarding spacing (0 to l2mm) between grid as well as inclination(0 to 30°) , it is thus possible to adjust the amount of waste and its quality to the requirements and the different types of raw material.

Effective control of feed by the electronic feed regulator like P. E cell in the feeding section of the modern beater.

The aero dynamic principle of separation of trash from lint is employed in shirly opener and Airjet cleaner.

Loose beating technique is employed in step cleaner for good opening without any harsh beating. Also Micro dust extraction, improve the processing performance of the O.E. spinning.

The advantage of modern beater is like mono cylinder is that the impurities are separated from cotton without being crushed and this proves favourable during subsequent operations.

Special feature of the axiflo cleaner is that fibre contained in large tufts can not get entangled or lost through the grid. They remain in the machine till they are transformed into small tufts and release their impurities. The position of the adjustable guide plate between the two cylinder decides how long the tufts remain under the influence of the each cylinder.

All modern beaters are simple in construction and efficient unit suitable for all classes of cotton.

Maximum trash extraction.

Adjustable grid bar profile to optimise cleaning efficienty and suitable to process different varities of cotton.

Opening and beating are combined in the same machine for effective cleaning.

Less nep generation.

Less floor space.

Minimum maintenance.

Reduced power consumption.

Good blending action,

Improved yarn strength.

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Proper selection and positioning of machines in blow room line

Feeding techniques of all the opener and cleaning machines can be broadly classified into two types.

1. Loose feeding (free beating points)

Examples: Vertical opener, step cleaner, mono cylinder, S.R.R.L. Opener, Axiflo cleaner, etc. ,

2. Semi-fast gripped feeding (controlled feeding)

Examples: Porcupine opener, 3 bladed beater, ERM cleaner,etc., Loose feeding beating technique is employed in the initial cleaning line so that heavy impurities are removed, otherwise they will be crushed into fragments while fed into gripped feeding through pair of feed roller and it is very difficult to Remove crushed impurities.

Certain machine gives its best in terms of cleaning efficiency, it must be fed with material that has been preopened to a certain degree.

The kirschner beater is a minor cleaning point and because
of its intensive combing action and it improve the evenness and
texture of lap. So it must be placed as the last machine of the
scutcher.

Proper speeds & settings:

This decides the amount of opening & cleaning that can be achieved by a machine. High beater speed & closer beater settings gives better cleaning. But, beater speed & setting depends upon type of cotton, maturity & trash content. Improper setting, speed results fibre damage, nep generation of cotton.

Type of raw material to be processed : Selection & No. of openers & beaters depends upon the type of cotton & trash in them Long, finer & immature cottons cannot be subjected to too many cleaning points, since over treatment will results fibre damage, and neps.

low grade cotton with high trash content will require more beating points.

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MONO CYLINDER CLEANER in Blowroom | working principle

Object : To open and clean the cotton.

Advantages : Impurities are separated without being crushed.

This proves favourable during subsequent operations.
Type : Loose feeding pin opener.

The well opened tuft of cotton from mixing bale opener enter the machine at right angles to the pin cylinder axis.

The pin cylinder has 8 rows of six pins each, arranged spirally -around its circumference.

Due to the collision of the cotton tufts with rapidly revolving pin cylinder against grid bar, impurities from cotton is extracted and passed through the spacing of the grid bar.

After the tufts come into the contact with the grids for the first time, they are flung into the top part of the housing. Owing to the guide plate, the tufts moves along a helical path, so that they fall on the pin of the cylinder again and retaken past the grid a second time. At the same time the tufts are turned over, so that all their surface are brought into contact with grid, assisting the removal of dirt. The spiral path is continued by the guide plate and the tufts pass over the grid a third time, after which they leave the machine at the outlet.

The grids are arranged in two separate section which can be adjusted individually. The grid can be adopted to handle any degree of impurities and opening in the cotton to be processed by means of the lever provided with the scales. The grid can be adjusted regarding spacing ( 0 to 12 mm) between the grid bar, as well as inclination ( angular setting of the grid bar -0° to 30°). It is thus possible to adjust the amount of waste and its quality to the requirements and the different types of raw material ,

Magnetic Double Elbow : This is installed in mono cylinder to remove larger or smaller solid foreign bodies of metallic and non-metallic origin. By deviating the fibre-air stream through a sharp angle, heavy particles are thrown in to the metal box by inertia. Light metallic parts are further more attracted by a permanent magnet plate.V

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Blow room - Maintenance program

Maintenance is a program to keep all the parts of the machine in perfect condition with minimum wear and tear.

Preventive Maintenance in Blow Room;

It means to attend and check the machines regularly and systematically and defects are discovered and remedied before they cause a need for, major repair and before the wear & tear of the machine starts affecting the quality and production,

	Parts to be inspected	Rating &   Action taken Remarks Repaired/replaced
	check the condition of
1	spikes on lattice &lattice   tension	If the part is defective, write   "poor & needs Correction" in the rate & Remark column.
2	Striking edge of all the beaters
3	Feed roller weighting & its setting with beater.	The parts that are replaced or repaired   will    be entered by maintenance incharge.
4	Position of damper & air current in the cage.
5	Sharpness of blade/spike/pins of    beater.	Importance of maintenance in Blow Room.
6	Stripping rail setting in beater.
7	Function of P.E. cell swing door  & other feed control mechanisms.	If   a     serious breakdown occur in Blow
8	Condition   of   pedal feed   control mechanisms.

 

9	Calender Roller bearing & its weighting.	Room, a high   proportion
		of a Mills production will
10	Racks condition & Effectiveness	be stopped causing the
	of brake.	subsequent process to   be
11	Timing and synchronisation of	short of material.
	auto doffing mechanism.	This can be avoided to
12	Lap length measuring motion.	some extent by a thorough
13	Lap hardening Mechanism.	inspection and systematic
14	Lubrication system	Programme of   maintenance.
15	Al1 bearings-condition.	which can also helps to
16	Belt,     gear,    chain,    Robe &	reduce     the      1ap
	all driving connection.	irregularities and improve
17	Motor & its pulley condition.	the cleaning efficiency.
18	Roller vibration/ Eccentricity
19	Speed & settings.
20	Pan whether chocked with dust,
	or not.
21	R.H.% & Temp condition.
22	Ratio of fan to beater speed &
	Air current.
23	Robe & Bls tension.
24	All nuts, Bolts, screws-tightening
25	Check for any rough places on
	various rollers or calenders

Routine Maintenance in Blow Room: It means to attend the machine and maintenance work is carried out as per the maintenance schedule so as to maintain the Machine in perfect condition with minimum wear & tear.

Nature of operation                                                              Frequency

 

1. Dismantling -Checking- thorough
cleaning & resetting of
i) Cage Unit, ii) Lap doffing unit                                  Every month

iii) Lap measuring Motion
	iv) Lap hardening Mechanism.
	v) Piano feed regulating Motion
2.	Cleaning of grid bar	Every shift
3.	Removal of droppings from beneath
	the grid bar.	Twice per Shift
4.	Straightening of bent pins of	Whenever needs
	kirschner beater and sharpening the
	beater blade.
5.	Polishing of grid bar.	6 months
6.	reversal of beater blade.	1 year
7.	Re dressing of beater blade	2 year
8.	Clean inside the cage	each shift.
9.	Applying Black-lead powder inside the
	cage	periodically
10	. General cleaning	.15 days
11	. Lubrication of all the gear wheel	Daily & greasing at
	&. bearing.	the time of frame cleaning.
12	correct the leakage places in the
	entire pneumatic duct line.	Every week.

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