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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