Structure Of Rotor Spun Yarn

  • Open end spun yarns are basically three part construction. There is the core of substantially straight fibres , there is next the body of more loosely wound fibres , & then there are the tightly wound belts .
  •  some fibres may fall into more than one type.
A class 1 fibre
  • It  should become firmly embedded in the groove of the rotor before being picked up by the yarn tail & integrated into the yarn under considerable tension .
  •  class 1 fibres should therefore go into the yarn under tension. Class 1 fibres therefore go into the core of the yarn.
A class 2 fibre
  • It  starts to be integrated while it still lies mainly inside the transport tube , i.e. , Before it comes under the influence of the rotor & before it comes under the influence of the rotor & before it has any centrifugal force applied to it , so that the tension within the fibre is very low.
  • This type of fibre therefore starts as a rather loosely wound surface fibre .
  •  however , as its trailing end is withdrawn progressively from the tube, it makes increasing  contact with the rotor surface, & the tension in the fibre builds up so that the tail end of the fibre tends to work its way into the core of the yarn.

A class 3 fibre

  • It is picked up at some point along its length , the leading part being pressed onto the rotor surface by centrifugal force while the trailing part is still in the tube.
  •  This results in the formation of a leading hook. Furthermore , the original leading end , being under tension ,enters the core of the yarn , whereas the original trailing end starts on the surface but works its way into the core as in the case of class 2 fibres .
  • Class 3 fibres should therefore form leading hook such that both ends are in the core while the fold appears on the surface & may form a belt.
  • As the tail of bridging fibres ploughs round the groove , it disturbs or ruffles some of the fibres that are already in the groove & thus forms loops or folds in them. These loops tend to be held in place by frictional contract with neighboring fibres , so that many of them persist into the yarn. Small loops may appear in the yarn as such, but longer ones become folded over & either become trapped in the yarn as central deformation or wrapped around the outside in the form of belts.
  • Belts can contribute little to the strength of the yarn , but their presence may explain why open - end spun yarns have greater resistance to abrasion . furthermore , in the absence of a comprehensive pattern of fibre migration , it may be only the belts that hold the yarn together.


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