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Opening Roller

  • The teeth of the opening roller [a] pass at high speed [ 35 m/s] through the fibre beard being slowly pushed forward by the feed roller .
  • By means of this continuous intensive combing action, the opening roller carries along by friction all fibres emerging from the clamping nip between the feed shoe & feed roller.
  •  The projecting fibre beard takes on a wedge shaped form.
  • Combing out will be more intensive & even if:
    • The thinner the fibre strand {sliver fineness},
    • The more parallel the fibres arrangement
    • The more highly straightened the fibres,
    • The smoother the fibres [lustrous or delustred] ,
    • The shorter the clamping distance
    • The optimum rotational speed of the roller high roller speed will damage the fibres while lower roller speed would deteriorates yarn quality].
  • The clothing on the opening roller naturally exerts a great influence on the opening of the fibre strand with drafts of up to 2000.
  • This influence depends mainly upon the type of clothing, the shape of the teeth  & the point density.
  • The opening roller rotates between 5000 & 10000 rpm, usually between 6500 & 8000rpm.
  • Higher speeds of rotation are chosen where material throughout is high of rotation are chosen where material throughput is high [coarse yarns] & lower speeds where material throughput is low.
  • The diameter of the opening roller lies between 60 & 80mm, depending upon the manufacturers.
  • The opening roller is  the part subject to wear & must be periodically reclothed or replaced , depending upon the respective wear rate. If this is too long delayed , then yarn quality & spinning conditions decline
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  • In processing synthetic fibres, a low tooth angle of rake is chosen so that the fibres are treated gently.
  •  In some cases, it is necessary to operate with low roller rates of rotation to avoid heat damage to the fibres.
  • The required high degree of opening can nevertheless be obtained by locating the clothing close together at the feet to give a higher point density.
  • Very sensitive fine fibres can be processed with an os25 clothing having an angle of rake of only 9 degrees.
  • The clothing of opening roller depends upon type of fibre, fibre characteristics & the material throughput {coarse or fine yarns}.
  • Basically a distinction is drawn between two clothing types : metallic clothing & needle clothing.
  • Metallic clothing are generally used today in short-staple spinning because they are robust & have a very good opening capability.
  • The use of needle rollers is generally limited to the processing of raw materials that do not separate easily from the clothing.
  • Two clothing types have found wide acceptance
    • OS20 ,with an angle of attack of 25degrees for cotton , viscose & blends of those materials &
    •  OS21, with an angle of attack of 12degrees for synthetic fibres & all blends  containing synthetic fibres.



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