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Rotor Spinning for Wool

  • The longer staple length of wool , its general coarseness as a fibre , the presence of the wool scales , burrs & remnant trash content, its crimp frequency , the greater sensitivity of wool with with respect to specific mechanical stresses causes troubles for rotor spinning of the wool fibres.
  •  Because its lead to a larger rotor diameter , lower rotor speeds & comparatively high twist factors  & also more rotor deposits.
  • Staple length should be less than rotor diameter.
  •  Spinning is limited to minimum of 90-120 fibres in the yarn cross section.
  •  There shouldn't be a residual fat content of 0.5-0.7% in the fed sliver. Also sliver should content fibres of low crimp frequency.
  • For this purpose back-washing in a solution of sodium bisulphite & drying under tension] should be carried out prior to spinning.
  •  Purity of fibre stock is very important.
  • Stretch breaking is an alternative method for preparing the spinning stock. Normal tops may be used for rotor spinning if the staple length is reduced by stretch breaking .
  • The staple diagram can then be altered by breaking the longest fibres in several draft zones.
  • Results have shown that  all other things being equal, broken slivers can be spun with about 20% less twist than for carded slivers.
  • The distance between the feed roller & opening roller has been increased by 40mm.
  • To avoid damage to fibres.
  • The opening roller has been widened.
  • Pinned type opening rollers are used.
  • The alternative opening process utilizes a fibre selector [it consists of a cylinder created by staggered lamellae, each of which takes the form of an equilateral triangle with rounded corners] in conjunction with a double-apron draft feed.
  • The selector cylinder presses against a rubber covered roller & acts as a draft cylinder , applying very high draft ratios.
  •  The fibre end is nipped between the selector & rubber covered & is removed from the sliver without a hooked configuration.
  •  Rotor with a diameter of 90-100mm., V-shaped groove & without additional surface coatings were found to give best results. A smooth doffing tube is also recommended.

 



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