Blow room:
Blow room is the first stage of yarn manufacturing. In this section, fibre is opened, cleaned, mixed, and micro-dust is removed.
Objectives of blow room:
- To open the compressed bales of fibres.
- Remove dirt and dust, broken leaf, seed particles or any other foreign impurities from the fibres.
- To transfer the opened and cleaned fibres into a sheet form of definite width and uniform wt./ unit length which is called a lap.
- To roll the lap of predetermined length into a cylindrical shape around a lap pin.
- To transfer the lap from the lap pin to a lap road to suitably handle and feed it to the subsequent m/c (carding)
Wastage of blow room:
- Dropping
- Dust
- Filter waste
Faults in Blow Room:
These are the common faults occurred in the blow room section in yarn spinning.
- Uneven lap: Patchy, sticky, thick & thin places in the lap.
- Irregular lap: Lap of various shape, length & wt/unit length. This type of lap is not the same as required lap parameters.
- Soft lap: Less compact lap.
- Conical lap: If the width of lap increases or decreases with respect to its initial width.
- Barrel-shaped lap: If the thickness of the lap in middle is more than that of at the border sides.
- Others: Licking lap, defective selvedge, dirty lap etc.
Carding:
Carding is the second stage of the yarn manufacturing process in conventional spinning line. Carding is called the heart of spinning. The main function of carding is to break up locks and unorganized clumps of fibre. Blending, opening, parallelizing each fibre is also done by carding.
- Input: Fibre sheet or lap
- Output: carded sliver.
Objects of carding machine:
- To open the tuft of fibres.
- To make the fibres parallel and straight.
- To remove remaining trash particles.
- To remove short fibres.
- To remove neps.
- To produce a wave-like fibre called sliver, which is uniform in per unit length.
Wastage in carding:
- Taker in waste
- Flat strip
- Motes and files
- Sliver cut
- Filter waste
Carding faults:
- Sliver variation,
- Cloudy web,
- Hole in web,
- High nep count,
- Web sagging,
- etc.
Drawing:
In this stage, fibre are straighten and fibre blending can also be done. In drawing slivers are elongated when passing through a group of pair rollers, each pair is moving faster than the previous one.
- Input: carded sliver.
- Output: drawn sliver.
Objects of draw frame:
- Straightening of crimped and hooked fibres.
- Paralleling of fibres.
- To produce a more uniform sliver of definite wt./yds.
- To reduce the wt./yard of materials fed.
- To make perfect blending/ mixing of the component fibres.
Wastage in draw frame:
- Filter waste.
- Cleaner waste.
- Sliver cut.
Combing:
Combing operation is done by comber machine. Normally combing process is used to produce smoother, finer, stronger and more uniform yarns.
- Input: drawn sliver.
- Output: combed sliver.
Objects of comber:
- To remove the fibres shorter than a predetermined length.
- To remove remaining impurities in the comber lap.
- To remove neps in the carded sliver.
- To make the fibres more parallel and straight.
- To produce a uniform sliver of required per unit length.
Comber wastage:
The wastage which is removed from the comber machine during processing is known as combers noil. It is expressed as a percentage. It is mainly of short fibres and neps.
Combing faults:
- Thick and thin place across the width of the web.
- Group of curly fibres leaving the detaching roller.
- Cotton coming through at one head.
- Detached roller lapping.
- Irregular sliver.
- The long fibre in the waste.
Speed frame:
In yarn manufacturing technology, speed frame is situated after the comber. Speed frame or simplex machine draft the sliver to reduce weight per unit length. In speed-frame give some twist to give strengthen the yarn.
- Input: drawn (combed) sliver.
- Output: roving.
Objects of speed frame:
- Attenuation of drawn (combed) sliver to a suitable size for spinning.
- To insert a small amount of twist to strengthen the roving.
- To wind the twisted strand roving into a bobbin.
Wastage in speed frame:
- Slubs
- Snapping
- Dirt or oil strained roving
- Slack ends
- Incorrect twisting
- Irregular roving
- Stretched roving
- Cut roving
- Ridgy bobbins
- Soft bobbin
Ring frame:
Ring frame is the last machine to manufacture yarn. It gives draft to the roving until the required fineness is achieved. And give insert twist to the drafted strand to form yarn of required count and strength.
- Input: roving.
- Output: yarn.
Objectives of ring frame:
- To draft the roving fed to the ring-spinning frame.
- To insert the necessary amount of twist.
- To wind the twisted thread or yarn on a cylindrical bobbin or tube.
Wastage in ring frame:
There are two types of wastage in ring frame. They are:
(i) Soft waste:
- Pneumafil
- Bonda
- Roving
- Sweeping
(ii) Hard waste:
- Broken end of the yarn
- Yarn waste in the winding.