Yarn manufacturing

Yarn is a long continuous length of inter-locked fibers suitable for use is the production textiles.
Yarn may be defined as arrangement of fibers uniformly to a continuous mass of fiber bound together by trust. The yarn may be spun from staple fiber or continuous filaments.
A genetic term for a continuous strand spun from a group of natural or synthetic staple fibers or filaments used in weaving, knitting to torn fabric.

        Classification of yarn
Yarn can be classified according to

a) Length of fiber
         i) Spun yarn-- Short staple, Long staple
         ii) Filament yarn-- Mono filament, Multi filament
b) No of strand
         i) Single yarn
         ii) Double yarn or ply yarn
         iii) Cable yarn

• Ply yarn

All yarns are single ply unless twisted with another yarns. Terms used are two ply if two yarns are twisted together and three ply if three yarns are twisted together.

• Cable yarn

A cable yarn is made smaller plied yarns twisted together. The easiest cable yarn is a four ply and it is a nice way to use up a bunch of singles you have got lying around.
c) Spinning system
         i) Ring yarn
         ii) Rotor yarn
         iii) Worsted yarn
         iv) Woolen yarn
d) Types of blend
         i) Cotton + Polyester
         ii) Cotton + Viscose
         iii) Cotton + Acrylic
e) Process sequence used
         i) Carded yarn
         ii) Combed yarn

• Sliver

A loose of continuous untwisted strand or a strand of loose untwisted fibers produced in carding.

• Roving

A collection of relatively fine fibrous strands used in the later or final processing of preparation for spinning.

Flow chart of carded yarn

Blow room---> Carding--->First drawing frame---> Second drawing frame---> Speed frame---> Ring frame

Flow chart of combed yarn

Blow room---> Carding---> First drawing frame---> Lap former---> Comber---> Second drawing frame--->Speed frame---> Ring frame
   
Object of blow room

i) To open compress fiber tufts into smallest tufts.
ii) To mix or blend of fibers.
iii) To remove foreign materials like trash, dust, leaves or others.
iv) To produce a lip of definite weight per unit length.
v) To feed fiber tufts directly to the carding process.

Defects of blow room

1) Poor cleaning efficiency
      i) Poor cleaning efficiency is due to the less beater speed.
      ii) Irregular feed.
      iii) Higher distance between to beater to grid bar.
      iv) Blockage the cage.
      v) Damaged striker of beater.
     vi) Excessive moisture containing in fiber.
2) Soft lap
      i) Less calender roller pressure.
      ii) Low amount of moisture.
3) Conical lap
      i) Irregular suction in the cage.
      ii) Excessive moisture.
4) Barrel shaped lap
5) Lap licking
      i) Excessive moisture
      ii) Too low calender roller pressure.
6) High neps generation
      i) Condition of beater and associated components.
      ii) High moisture content
      iii) Closer settings
      iv) Excessive fan speed

Object of carding

i) To open the fibers tufts and clean again.
ii) To individual the fibers by carding action, reduction of neps.
iii) To produce a continuous strand of fibers slivers of definite weight per unit length.


Parts of the carding machine
i) Lap feed                                   
ii) Lap
iii) Feed plate
iv) Feed roller
v) Motes knife
vi) Licker in
vii) Under caging
viii) Back plate
ix) Cylinder
x) Revolving flats
xi) Front plate
xii)Doffer
xiii) Doffer comb
xiv) Trumpet
xv) Calender roller
xvi) Sliver guide
xvii) Coiler head
xviii) Sliver can
xix) Sliver can drivers

Action involved in carding machine

1) Carding action: When two closely space wire surfaces moves against each other and the surfaces have relative speeds for the reduction of fiber mass is called carding action e.g, cylinder and doffer; flats and cylinder action.

2) Stripping action:When two closely space wire surfaces move some direction and the surfaces have relative speeds for the reduction of fiber mass is called stripping action.

Object of drawing frame
i) To straight the hook fibers along the axis of the sliver.
ii) To parallel the fiber to each other.
iii) To reduce the weight per unit length of the sliver.
iv) To improve the regularity of the sliver.
v) To blend or mix the fibers for the homogeneous sliver. 

Object of comber

i) To remove short fibers below a preselected length so that the spinner enable to produce finer yarn then that can be spun from the same cotton in the carded step.
ii) To remove neps and impurities.
iii) To improve fiber parallelization and to make strength.

Object of simplex or speed frame

i) Attenuation of drawn sliver to roving form of required hank by drafting.
ii) Insert a small amount of twist to give required strength of roving.
iii) Winding the roving onto bobbin.
Build the roving such a form which will facilitate handling and transfer to the next process.

Object of ring frame

i) Draft the roving until the required count is achieved.
ii) Twist the drafted strand to form yarn of required count and strength.
iii) Wind the twisted yarn on to bobbin for suitable storage, transportation and further processing.