Effect of Processing Factors on the Incidence of Yarn Faults in ...
Yarn manufacturing (yarn faults)
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Transcript of Yarn manufacturing (yarn faults)
Submitted by: Asif Ahmed TonmoyID: 131-23-3505 ; Sec: D(L 3T1)
Assignment topic: Different kinds of yarn faults.
Submitted to: Lecturer
Daffodil International University
Nadim Haider Maruf
Yarn faults
The defects of yarn is called Yarn faults.When an uneven place or impurities or any
other lack of minimum quality is found in a yarn is called yarn defects or faults.
Yarn content in the cop is less
EFFECTEfficiency loss in ring frame
•Drop in winding efficiency •More knots for a given length of wound yarn
CAUSESUnder utilization of bobbin height
Lower number of coils /inch Higher chase length Cop bottom bracket properly not set Improper selection of ratchet Ratchet pawl pushing number of teeth's /movement in the ratchet wheel Spinning empties wall thickness is high
RECTIFICATIONOptimum chase length, coil spacing and wall thickness of empty cops tobe ensured
1. Ratchet/pawl movement to be properly set 2. Free space of only 7.5mm to be maintained at the top and bottom of the
cop 3. Free space only 0.75mm only to be maintained between full cops and the
ring
An abnormally thick place or lump in yarn showing less twist at that
place.
EFFECTMore end breaks in the next process.
Damaged fabric appearance. Shade variation in dyed fabrics.
CAUSES
Accumulation of fly and fluff on the machine parts. Poor carding. Defective ring frame drafting and bad piecing Improperly clothed top roller clearers.
RECTIFICATION1. Machine surfaces to be maintained clean. 2. Proper functioning of pnemafil /roller clearers to be ensured. 3. Broken teeth gear wheel to be avoided and proper meshing to be
ensured. 4. Better fiber individualization at cards to be achieved. 5. Optimum top roller pressure &back zone 6. Setting at ring frame to be maintained.
Yarn containing rolled fibre mass, which can be clearly seen onblack board at close distance; measurable on Usterimperfection Indicator.
EFFECTDamaged fabric appearance
•Shade variation in the dyed fabrics •An abnormally thick place or lump in yarn showing less twist at that place is called slubs
CAUSESAccumulation of fly and fluff on the machine parts
Poor carding. Defective ring frame drafting and bad piecing Improperly clothed top roller clearers.
RECTIFICATIONMachine surfaces to be maintained clean.
1. Proper functioning of pnemafil/roller clearers to be ensured.
2. Broken teeth gear wheel to be avoided and proper meshing to be
ensured.
3. Better fiber individualization at cards to be achieved.
Measurable by Uster Imperfection Indicator and observable on appearance
EFFECTEccentric top and bottom rollers
•Insufficient pressure on top rollers •Worn and old aprons and improper apron spacing •Improper meshing of gear wheels •Mixing of cottons varying widely in fiber lengths and use of immature cottons
CAUSES Eccentric top and bottom rollers Insufficient pressure on top rollers Worn and old aprons and improper apron spacing Improper meshing of gear wheels Mixing of cottons varying widely in fibre lengths and use of immature cottons
RECTIFICATIONEccentric top and bottom rollers to be avoided
1. Top arm pressure checking schedules to be Maintained strictly 2. Wide variation in the properties of cottons used in the mixing to be avoided 3. Better fiber individualization at cards to be achieved. 4. Correct spacers to be utilized
Yarn which is weak indicating lesser twist
EFFECT:
More end breaks in subsequent processes
•Shade variation in dyed fabrics
CAUSES:Slack tapes dirty jockey pulleys
Less twist in the yarn
Bad clearing at the traveller
RECTIFICATION:Vibration of bobbins on the spindles to be avoided
1. Proper yarn clearing to be ensured
2. Periodic replacement of worn rings and travellers to be effected
Yarn stained with oil
EFFECTDamaged fabric appearance
•Occurrence of black spot in fabric
CAUSESCareless oil in the moving parts, over head pulleys etc
Piecing's made with oily or dirty fingers
Careless material handlings
RECTIFICATIONAppropriate material handling procedures to be followed
1. Oilers to trained in proper method of lubrication
2. Clean containers to be utilized for material transportation
Very small snarl-like places in the yarn which disappear when pulled with enough tension or Yarn with spring –like shape
EFFECTMore breaks in winding
•More noticeable in polyester and cotton blended yarns
CAUSES Mixing of cottons of widely differing staple length Closer roller settings Eccentric top and bottom rollers Non optimum temperature and relative humidity in the spinning shed Over spinning of cottons
RECTIFICATIONOptimum top roller pressure to be maintained
1. Mixing of cottons varying widely in fibre length to be avoided
2. Use of optimum roller settings
3. Use of properly buffed rollers free from eccentricity to be
ensured
Short thick place