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Dedusting In Drawframe

  • During drafting , fibres are displaced longitudinally in relation to each other , & the attendant frictional action loosens  any dust particle adhering to the fibre surface .
  • A suitably applied suction device ,can ,be remove a substantial amount of liberated dust.
  •  Studies of the efficiency of dust removal at the drawframe have indicated that up to 90% of the liberated dust can be removed if suction is applied at the top & bottom rollers of drafting zones & that a further improvement is obtained if suction is applied at the sliver trumpet.
  •  This applied suction with two drawframe passages reduces rotor faulings by 30 -40 %.
  • If the drawframe is to be utilized for dedusting of sliver feed , it is essential to fit a flow control that can be varied to increase the rate of air-flow according to increased sliver weight or production speeds or both.
  •  It is also important that exhausted air is not discharged straight into the workroom , since very fine dust can pass through the filter cloth of machine & accompany the air back into the room .
  •  The exhaust duct should be coupled with the ducts of the cards  & piped into the controlled filter plant before the air is recycled.
  • The main task of drawframe is to ensure high sliver evenness over both short & long lengths.
  •  Sliver unevenness over short & medium lengths  leads to count variation in the yarn.
  • The third task of the drawframe lies in the creation of a high degree of parallelism.
  • The higher the parallelism of the fibres in the sliver, the better is the opening roller able to separate the strand into individual fibres, with a corresponding noticeable improvement in yarn quality & running performance .
  • Wherever possible , two drawframe passages should therefore be used.
  • Good coiling of the sliver in the can is also important, so that loops, knots & double slivers do not arise during withdrawl for infeed into the rotor spinning machine. Further , the fibres should not be permitted to split apart.
  •  Piecing of slivers leads to ends down or thick places in the yarn.

 



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