16. What is the main yarn fault caused by the Bobbin Holders?

The main yarn fault contributed by bobbin holders is long thin fault caused by creel stretch.

Generally in classimat results, the readings of H1, and I1 faults denotes the long thin faults. Long thin fault as per classimat system is defined as faults which have 30 to 40% cross sectional area of normal cross sectional area and extends to 32 cms. There are various reasons for occurrence of the long thin faults, as listed below.

CONTRIBUTORY CAUSES FOR YARN IMPREFECTION

IN RING SPINNING PROCESS: (source- SITRA)

  1. High fiber length variation and immature fibres.
  2. Uneven roving.
  3. Eccentric top and bottom rollers in ring spinning.
  4. Insufficient pressure on top rollers.
  5. Too high a draft in ring frame.
  6. Worn out rings.
  7. Traveler clearer set closer.
  8. Improper setting of tension bar.
  9. Excessive fly liberation in ring frame.
  10. Damaged top/bottom roller clearers.
  11. Jerky movement of ring rail.
  12. Cracked and worn bobbins.
  13. Incorrect bobbin diameter and fit of bobbins.
  14. Loose and worn out aprons.
  15. Incorrect shore hardness of top rollers.
  16. Incorrect apron nip opening and settings.
  17. Excessive twist in roving.
  18. Lack of control in temperature and humidity.
  19. Creel stretch in ring frames due to the obstruction in free rotation of bobbin holders.

CONTRIBUTORY CAUSES AT PREPARATORY PROCESS FOR YARN FAULTS:

  1. Excessive incidence of web falling (partial or full) or lap licking at cards.
  2. Higher drafts at creel and coiler zone in draw frame.
  3. Excessive variations in top roller pressure in draw frames.
  4. Faulty stop motion of draw frames.
  5. Loose top roller and bushes in draw frames.
  6. Disturbance in the free rotation of creel calender rollers in draw frames.
  7. Sliver stretch of the creel in speed frames due to too high a creel draft.
  8. Too high a break draft in speed frame.
  9. Excessive roving stretch due to improper function of builder mechanism.
  10. Use of bobbin at speed frame with wide variation in bare bobbin diameter.
  11. Sliver splitting in speed frames while drafting.
  12. Use of excessive tension weights in single end winding.