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PROCESS PARAMETER IN BLOW ROOM - 4

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DEDUSTING:

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 effecive 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 opners 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, eventhough  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  turbulance  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 sawginned), 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 proudction 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 performace  , and to run the line without any electrical system breakdowns.

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