Yarn Manufacturing Process

Ginning:
The process of separating the seeds and debris from the cotton fibers is known as ginning. Cotton ginning process is done by cotton gin machine but before ginning was done by hand.

Types of ginning process:
There are three types of ginning. They are
  1. Knife roller gin for Indian and Pakistani cotton
  2. Macarthy roller gin for long staple cotton
  3. Saw gin- Used for American, west African, Pakistani cotton
Point should be considered for fiber during processing:

Main factors:
  • Length
  • Fineness
  • Maturity
  • Uniformity
  • Trash content
Other properties:
  • Pliability
  • Cohesiveness
  • Tensile strength
Mixing and blending:

Mixing:
In mixing, different grades of same fibers are kept together for yarn production. It is generally meant as the intermingling of different classes of fibers of the same grade. E.f USA pima grade 2, CIS.

Blending:
It is meant as the intermingling of different kinds of fibers are kept together for yarn manufacturing. E.g. polyester & cotton, Viscose & cotton.

Objectives of Mixing and blending:
  • Economy
  • Processing performance
  • Functional properties
Flow chart of yarn manufacturing process
Flow chart of yarn manufacturing process
Fig: Yarn production flow chart
Blow room:
Blowroom is the first stage of yarn manufacturing. In this section fiber is opened, cleaned, mixed , micro dust removed. Fiber bale is the input material of blow room and output product is uniform lap or fiber sheet.

Objectives of blow room:
  • To open the compressed bales of fibers.
  • Remove dirt and dust, broken leaf, seed particles or any other foreign impurities from the fibers.
  • To transfer the opened and cleaned fibers into a sheet form of definite width and uniform wt./ unit length which is called lap.
  • To roll the lap 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)
Action of blow room line:
  • Action of opposing spikes
  • Action of air currents
  • Action of beaters
  • Regulating action
Wastage of blow room:
  • Dropping
  • Dust
  • Filter waste
Faults in blow room:
  • Irregular lap
  • Knocking off before completion of full lap
  • Rough appearance of full lap
  • Lap sheet thicker at one side than at the others
  • Soft lap
  • Lap licking
  • Dropping under beater and grid bars
  • Formation of conical lap
  • Formation of split lap
  • Barrel shaped lap
  • Ragged lap selvedges.
Types of beater in blow room:
  • Porcupine beater
  • Bladed beater
  • Multiple beaters
  • Krishner beater
Carding:
Carding is the second stage of yarn manufacturing process in conventional spinning line. Carding is called heart of spinning . Main function of carding is to breaks up locks and unorganized clumps of fiber. Blending, opening, parallelizing each fiber is also done by carding. Fiber sheet or lap is the input material of carding and sliver is the output product of carding.

Objects of carding machine:
  • To open the tuft of fibers
  • To make the fibers parallel and straight
  • To remove remaining trash particles
  • To remove short fibers
  • To remove naps
  • To produce a rave like fiber called sliver, which is uniform in per unit length.
Main actions of carding machine:
  • Action between feed roller and taker in.
  • Action between taken in and cylinder.
  • Action between cylinder and flat.
  • Action between cylinder and doffer
Useful sliver hanks of different count:

Count of yarn:                10s       20s      32s      40s       60s      80s
Hank of carded sliver:    0.125   0.125    0.13    0.135    0.145    0.165

Wastage in carding:
  • Taker in waste
  • Flat strip
  • Motes and files
  • Sliver cut
  • Filter waste
Draw frame:
Draw frame is a machine for combining and drawing slivers. Carded slivers are fed into the Drawframe. In this stage fiber are straighten and fiber blending can also be done. In drawing slivers are elongated when passing through a group of pair rollers, each pair is moving faster than previous one.

Objects of draw frame:
  • Straightening of crimped and hooked fibers.
  • Paralleling of fibers.
  • To produce more uniform of sliver of definite wt./yd
  • To reduce the wt./yard of materials fed.
  • To make perfect blending/ mixing of the component fibers.
Wastage in draw frame:
  • Filter waste
  • Cleaner waste
  • Sliver cut.
Comber:
Combing operation is done by comber machine. Normally combing process is used to produce smoother, finer, stronger and more uniform yarns.

Objects of comber:
  • To remove the fibers shorter than a predetermined length.
  • To remove remaining impurities in the comber lap.
  • To remove naps in the carded sliver.
  • To make the fibers more parallel and straight.
  • To produce a uniform sliver of required per unit length.
Necessary of combing:
The essential requirements to produce quality yarn are-
  • Clean fiber
  • Uniformity in length of fiber
  • Absence of naps
  • More parallel arrangement of fibers.
  • Straight fibers.
  • The above quality of fibers can only be obtained by combing.
Comber noel:
The wastage which is removed from comber machine during processing ia known as combers noel. It is expressed as percentage. It is mainly of short fibers and naps. Noel is used for lower count as raw material.

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.

Objects of speed frame:
  • Attention of draw 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.
Operation involved in speed frame:
  • Drafting
  • Twisting
  • Laying out
  • Winding
  • Building motion
Ring frame:
Ring frame is the last machine to manufacture yarn. It gives draft the roving until the required fineness is achieved. And give insert twist the drafted strand to form yarn of required count and strength.
Fig: Yarn production
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.
Operation involved in ring frame:
  • Creel in.
  • Drafting
  • Twisting
  • Laying out.
  • Building
  • Doffing.
  • Winding.
Wastage in ring frame:
There are two types of wastage in ring frame. They are

Soft waste:
  • Pneumafil
  • Bonda
  • Roving
  • Sweeping
Hard waste:
  • Broken end of yarn
  • Yarn waste in winding
Factors governing optimum spinning condition:
  • Spindle speed
  • Ring dia
  • Lift
  • Traveler wt.
  • Relative humidity
Yarn quality assessment:
  • Yarn count and its variation
  • Twist and its variation
  • Evenness CV% or U% of yarn
  • Strength and its variation (csp of yarn)
  • Imperfections.
Causes of end breakage/ End down:
If spinning tension is grater than yarn strength in ring frame, then end breakage is occurred and also due to roller lapping.

A. Technological causes:
  • Insufficient twist in yarn
  • If traveler fly off.
  • Subbing through
  • Stretched roving
  • Faulty drafting roller setting.
  • Faulty traveler selection.
  • Excessive yarn tension.
  • Improper atmospheric conditions.
B. Mechanical causes:
  • Faulty drafting system
  • Worn out ring and traveler
  • Faulty gear and wheels
  • Worn out of rollers
  • Faulty apron
  • Spindle vibration
  • Eccentric ring.
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