Yarn Faults or Defects and Remedies?

Yarn Faults or Defects and Remedies?

Answer:

Introduction:
yarn quality is influenced by various types of yarn faults which also affects the quality of fabric produced. During the yarn manufacturing process, various types of irregularities are generated in the yarn diameter regularly or at intervals which are known as yarn faults.

Yarn faults, causes, and its remedies:

01. Slubs

02. Neps

03. Snarl

04. Thick & think places

05. Soft yarn

06. Oil stained yarn

07. Crackers

08. Bad piecing

09. Oily slub

10. Kitty yarn

11. Hairiness

12. Foreign matters

13. Spun in fly

14. Corkscrew yarn

15. Slough Off

16. Starting mark/Stops

17. Gout

18. Knots

19. Excessive Hard Yarn

20. Rust Stain

21. Low Strength of Yarn

1. Slubs:

An abnormally thick area or lump in yarn displaying less twist at that area.

Effect:

A. More end breaks in the next process.

B. Damaged fabric appearance.

C. Shade variation in dyed fabrics.

Causes:

A. Accumulation of fly and fluff on the machine parts.

B. Poor carding.

C. Defective ring frame drafting and bad piecing

D. Improperly clothed top roller clearers.



Rectification:

A. Machine surfaces to be maintained clean.

B. . Correct functioning of pneumafil/roller clearers to be ensured.

C. Broken teeth wheel to be avoided and correct meshing to be ensured.

D. Higher fiber discrimination at cards to be achieved.

E. Optimum prime roller pressure &back zone

F. Setting at ring frame to be maintained.



2. Neps
yarn containing rolled fibre mass, which may be clearly seen on black board at shut distance; measurable on uster imperfectness indicator to be ensured.

Effect:

A. Damaged fabric appearance

B. Shade variation in the dyed fabrics

C. An abnormally thick place or lump in yarn showing less twist at that place is called slubs

Causes

A. Accumulation of fly and fluff on the machine parts

B. Poor carding.

C. Defective ring frame drafting and bad piecing

D. Improperly clothed top roller clearers.

Rectification:

A. Machine surfaces to be maintained clean.

B. Proper functioning of pnemafil/roller clearers to be ensured.

C. Broken teeth gear wheel to be avoided and proper meshing to be ensured.

D. Better fiber individualization at cards to be achieved.



3. Snarl

Yarn with kinks(twisted onto itself) due to insufficient tension after twisting

Effect:

A. Entanglement with adjacent ends causing a break

B. Damaged fabric appearance

C. Shade variation in dyed fabrics

D. Improper meshing of gear wheels

E. Mixture of cottons varied wide in fiber lengths and use of immature cottons

Causes:

A. Higher than normal twist in the yarn

B. Presence of too many long thin places in the yarn

Rectification:

A. Optimum twist to be used for the type of cotton processed

B. Drafting parameters to minimise thin places in the yarn to be adopted

C. The yarn to be conditioned

D. Correct tension weights and slub catcher settings to be employed at winding



4. Thick and thin places

Measurable by uste rimperfection indicator and observable on appearance

Effect:

A. Eccentric top and bottom rollers

B. Insufficient pressure on top rollers

C. Worn and old aprons and improper apron spacing

D. Improper meshing of gear wheels

E. Mixture of cottons varied wide in fiber lengths and use of immature cottons



Causes:

A. Eccentric top and bottom rollers

B. Insufficient pressure on top rollers

C. Worn and old aprons and improper apron spacing

D. Improper meshing of gear wheels

E. Commixture of cottons variable wide in fibre lengths and use of immature cottons.

Rectification:

A. Eccentric top and bottom rollers to be avoided

B. Top arm pressure checking schedules to be maintained strictly

C. Wide variation in the properties of cottons used in the mixing to be avoided

D. Better fiber individualization at cards to be achieved.

E. Correct spacers to be utilized



5. Soft yarn

Yarn which is weak indicating lesser twist



Effect:

A. More end breaks in subsequent processes

B. Shade variation in dyed fabrics

Causes

A. Slack tapes dirty jockey pulleys

B. Improper bobbin feed on the spls

C. Less twist in the yarn

D. Bad clearing at the traveler

Rectification:

A. Vibration of bobbins on the spindles to be avoided

B. Proper yarn clearing to be ensured

C. Periodic replacement of worn rings and travelers to be affected



6. Oil stained yarn

Yarn stained with oil

Effect:

A. Damaged fabric appearance

B. Occurrence of black spot in fabric

Causes:

A. Careless oil in the moving parts,over head pulleys etc

B. Piecing’s made with oily or dirty fingers  careless material handlings

Rectification:

A. Appropriate material handling procedures to be followed

B. Oilers to trained in proper method of lubrication

C. Clean containers to be utilized for material transportation

7. Crackers:

Small growl like places in the yarn which vanish when pulled with enough strain or yarn with spring-like shape

Effect:

A. More breaks in winding

B. More noticeable in polyester and cotton blended yarn

Causes:

A. Mixing of cottons of widely differing staple length

B. Closer roller settings

C. Eccentric top and bottom rollers

D. Non-optimum temperature and relative humidity in the spinning shed

E. Over spinning of cottons

Rectification:

A. Optimum top roller pressure to be maintained

B. Mixing of cottons varying widely in fibre length to be avoided

C. Use of optimum roller settings

D. Use of properly buffed rollers free from eccentricity to be ensured



8. Bad piecing:

Unduly thick piecing in yarn caused by over end piecing

Effect:

A. More end breaks in subsequent process

B. Increase in hard waste

Causes:

A. Wrong method of piecing and over end piecing

B. Twisting the ends instead of knotting

Rectification:

A. Tenters to be trained in proper methods of piecing

B. Separators to be provided

C. Excessive end breaks in spinning to be avoided



9. Oily slub:

Slub in the yarn stained with oil

Effect:

A. More end breaks in the ensuring process

B. Damaged fabric appearance

C. Shade variation in dyed fabrics

Causes:

A. Accumulation of oily fluff on machinery parts

B. Poor methods of lubrication in preparatory processes

C. Negligence in segregating the oily waste from process waste



Rectification:

A. Yarn contact surfaces to be kept clean

B. Oilers to be trained in correct procedures of lubrication

C. Proper segregation of oily waste from process waste



10. Kitty yarn:

Effect:

A. Damaged fabric appearance

B. Production of specks during dyeing

C. Needle breaks during knitting

D. Poor performance during winding

Causes:

A. Ineffective cleaning in blow room and cards

B. Use of cottons with high trash and too many seed coat fragments

Rectification:

A. Cleaning efficiency of blow room and cards to be improved

B. Optimum humidity in the departments to be ensured



11. Hairiness

Protrusion of fibre ends from the main yarn structure

Effect:

A. More end breaks in winding

B. Uneven fabric surface

C. Beads formation in the fabric in the case of polyester/cotton blends

Causes:

A. Use of cottons differing widely in the properties in the same mixing

B. Use of worn rings and lighter travellars

C. Maintaining low relative humidity, closer roller settings, and very high spindle speeds

Rectification:

A. Use of travellers of correct size and shape and rings in good condition to be ensured

B. Periodic replacement of travellers and suitable

C. Roller settings to be maintained

D. Optimum relative humidity to be maintained in the spinning room

E. Wide variation in the properties of cottons used in the mixing to be avoided



12. Foreign matters

Metallic components, jute flannel, and totally extraordinary comparative remote issues spun along the edge of yarn.



Effect:
A. Breaks throughout winding
B. Formation of holes and stains in fabric
C. Damaged fabric look



Causes:
A. Improper handling of travelers
B. Improper preparation of mixings
Rectification:
A. Removal of foreign matters(such as jute fibres, color fabric bits) to be ensured throughout preparation of blending
B. Installation of permanent magnets at correct
C. Places in blow area lines to be ensured

13. Spun in fly
Fly or fluff either spun next to the yarn or inexactly implanted on the yarn.

Effect:

A. More breaks in winding

Causes:

A. Accumulation of fluff over machine parts

B. Fanning by workers

C. Failure of overhead cleaners

D. Malfunctioning of humidification plant

Rectification:

A. Machinery surfaces to be kept clean by using roller pickers

B. Performance of overhead cleaners and humidification plants to be closely monitored



14. Corkscrew yarn

It is a double yarn which one yarn is straight and other is coiled over it

Effect:

A. Breaks during winding

B. Causes streaks in the fabric

Causes:

A. Feeding of two ends (instead of one ) in ring frame

B. Lashing -in ends in ring frame

Rectification:

A. Tenters are to be trained in piecing methods(or) practices

B. Pneumafil ducts to be kept clean and properly set

15. Slough Off

Thick bunches of yarn are woven into the fabric in the weft direction due to slipping off of coils of yarns from the pirn during weaving.

Causes:

A.   Improper package characteristics.

B.    Softly wound pirns.

C.    Harsh picking and/or poor shuttle checking.

D.   Poor humidity conditions during the storage of pirns.

RECTIFICATION:

A.      Ring rail movement to be set right

B.      Optimum ratio of winding: bindings coils and optimum chase length to be maintained

Remedies:

A.   Employ correct package characteristics in pirn winding.

B.    Ensure proper yarn tension during pirn winding in the case of rewound weft and in spinning in the case of direct weft.

C.    Check the picking and checking mechanisms.

D.   Condition the weft before putting it on loom.

 16. Starting Marks

A thick or thin place is produced in the fabric due to variation in pick density while starting the loom.

 Causes:

A.   Weaver letting back the fell of the fabric too close to the reed by faulty adjustment of take-up motion.

B.    Faulty functioning of anti-crack motion.

Remedies:

A.   Instruct the weavers about the correct procedure.

B.    Ensure correct functioning of the motion.

17. Gout

Foreign matters like lint or waste or pieces of harness strapping and leather accessories are woven into the fabric.

Causes:

A.   Indiscriminate throwing of waste by weavers.

B.    Foreign matter getting into the shed during weaving.

Remedies:

A.   Ensure cleanliness of machines and surroundings in the loom shed.

B.    Keep the frequent check on harness strappings and leather accessories for undue wear and replace them, if necessary

18. Knots

The ends of yarn joined by knot is called knotting & the end of yarn joined by knotless join is called splicing. 

So there are two methods of yarn joining:- 

1.     Knotting

2.     Splicing

3.     Bends

4.     Hitches

What is Knotting?

§  Knotting is tying two threads to each other or to tie thread to any other object.

§  The joint between one thread to another or object is called Knot.

Hitches - used when attaching rope, cord and yarn to an object or when an object is used as an anchor for the knot.

There are two main purpose of introducing knots in textile. 

§  Continuity knots:- are used for continuity of yarn.

§  Clearing knot:- are to substitute yarn faults during yarns clearing.

A knot should satisfy various requirements for different uses in textile industry which areas under 

§  It should be easy to tie.

§  It should Have good resistance to slippage.

It should be of size & shape that gives a little chance of catching or jamming from warp beam to cloth fell.