Open-End Rotor Spinning

This system differs to that of ring spinning in many ways. Unlike the conventional drafting and

spinning system there is a break in the continuity of the material and an open end is produced.

This open end must be rotated to introduce the necessary twist for the yarn formation. 

The fibre flow should be separated into individuals before being reassembled.

This system eliminates the ring, traveler, and spindle.

There is no ballooning to introduce problems in the air-drag. 

 It is rotate the yarn package at high speed is eliminated so power needed is thereby reduced.

      

Rotor Spinning 

Features

•         Ability to Automate
•         Rotor speed up to 150,000 rpm
•         Production speed up to 235 m/min
•         High speed, high strength piecing
•         Package size up to 5Kg
•         Flexibility – variable adjustment of draft, twist, and tension and rotor speed
•         High processing efficiency and lower downstream cost weaving/knitting
  Principles of OE spinning
  §Opening of feed sliver into individual fibres 
  §Assembling of individualized fibres 
  §Twist insertion 
  §Withdrawal of resultant yarn and winding onto a package  
  
  
  
  
  Opening/ Individualization and Fibre Feeding

  
  
  •Opening roller called opener or the beater
  •Opening roller speed =6500 – 9000 rpm
  •Surface speed =800 – 2500 m/min
  •Sliver count = 30 – 300 thicker than yarn count (draft)
   Fibre Assembling/Transport
           •The individual fibres are carried forward from the opening roller by an air

    current through the feed tube or transport tube. 

  •The conical shape of tube accelerates the air current leading to improved fibre 

    orientation and straightness.

  •The fibres carried by the air current are deposited at the grove in the form of a

    ring.

   
  
   
  

  Drafting
  
  
  •drafting from sliver to Final yarn count

  •Assembly of fibres in the spinning groove to give the linear density of yarn

    required.
  
  
                Twist Insertion
  •Centrifugal forces presses the fibre band against the inner peripheral surface

    of the rotor causing it to rotate and thereby inserting twist to the fibre assembly.

  •Rotor speed may vary between 50,000- 150,000 rpm depend on the fibre and

    yarn count

  •Theoretically one turn of twist is introduced for each revolution of the yarn end.

  •Direction of the twist is determined by the direction of rotation of the rotor.

   
  
  
  
  Twist (tpm) = Rotor speed (rpm) / Yarn delivery speed (m/min) 

  
  

  Yarn Piecing

  Yarn Properties

  •Structure

  –Fibres in the Rotor yarn are not well oriented as in the ring spun yarn

  –Core more twist, Sheath less twist

  –Bipartite Structure, Core contribute to strength and sheath for bulkiness

  –Wrapper fibres in the surface gives dull appearance

  
  

  •Strength and Extension

  –Due to inferior orientation, the fibre length utilization is lower, and therefore less strength than equivalent ring spun yarn (80-85%).

  –Higher extension at break than ring spun yarn

  
  

  •Yarn count

  –Yarn 15 tex or coarser.

  –Finer fibres are preferred. 

   
  

  •Unevenness and imperfection

  –Rotor yarn is relatively evener than equivalent ring spun

  –Fewer imperfection than ring

  
  

  •Flexural Rigidity

  –Higher flexural rigidity than ring spun (1.5-2.5 higher than ring spun)

  –Higher stiffness

  
  

  •Hairiness

  –Less hairy than ring spun

  
  

  •Abrasion Resistance/ Pilling

  –Higher abrasion resistance than ring spun.

  –Lower pilling resistance

  End uses of Rotor Spun Yarns

  
  

  
  

  
  

  •The rotor spinning has established very well in coarser and medium count

    sector to spin yarns economically in the range of 15 tex to 100 tex.

  
  

  •The marked evenness, abrasion resistance, and surface look enables these 

    yarns to find applications extensively in various products, like:

  –Denims, Jeans, knit fabric for inner wear, leisure wear, outer garments, T-shirts, sweaters, furnishing etc.