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Air Covered Yarn – Faults and Diagnosis

Jun 15, 2018

Posted in Air Covered Yarn

 
Air Covered Yarn - Faults and Diagnosis
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Just like any other yarn, Air Covered Yarn also experiences some faults which are caused mainly by two issues – Positional Faults and General Faults. Below are some of the faults that are seen in Air Covered Yarn.

  1. 1. Filamentation:
    1. a. Positional causes:
      1. i. Damaged/worn guides
      2. ii. Dirty heaters
      3. iii. Damaged friction discs
      4. iv. Waste on feed rollers/bowl
      5. v. Misthreading
      6. vi. Mechanical damage to supply yarn
    2. b. General Causes:
      1. i. Draw ratio too high
      2. ii. Heater temperature too high
      3. iii. Speed ratio too high
      4. iv. D/Y ratio too low
      5. v. Supply type/finish unsuitable
  1. 2. High break rate
    1. a. Positional causes:
      1. i. Worn nip rollers
      2. ii. Supply package misaligned
      3. iii. Damaged friction discs
      4. iv. Misthreading
      5. v. Damaged or badly wound supply yarn
    2. b. General Causes:
      1. i. Speed too high
      2. ii. Draw ratio in correct
      3. iii. D/Y ratio too high or low
      4. iv. Heater temperature too high
      5. v. Ambient conditions incorrect
      6. vi. Supply type/finish unsuitable
  1. 3. Tight spots
    1. a. Positional causes:
      1. i. Worn nip rollers
      2. ii. Incorrect threading
    2. b. General Causes:
      1. i. Unstable process specification
      2. ii. D/Y not optimum
      3. iii. Supply irregularity
  1. 4. Dye/Bulk variation
    1. a. Positional causes:
      1. i. Heater temperature fault
      2. ii. Heater cold top (dark dye)
      3. iii. Damaged friction discs
      4. iv. Incorrect twisting unit speed
      5. v. Damaged or worn guides
      6. vi. Take-up tension variation (bulk)
      7. vii. Worn/damaged nip roller
    2. b. General Causes:
      1. i. Unsuitable process specification
      2. ii. Dirty heaters
      3. iii. Supply irregularity
  1. 5. Webbing/ overthrows
    1. a. Positional causes:
      1. i. Misaligned cradle
      2. ii. Stroke too long
      3. iii. Loose or worn traverse guide
      4. iv. Wear or damage in traverse box
      5. v.Cradle catching on feed, back arm
      6. vi. Point of origin guide not central
    2. b. General Causes:
      1. i. Take-up tension too high
      2. ii. Wind angle too low
      3. iii. Taper angle too low
      4. iv. Radial disturbance too high
      5. v. Axial displacement very high
  1. 6. Poor package unwinding
    1. a. Positional causes:
      1. i. Stroke length incorrect
      2. ii. Cradle settings incorrect
      3. iii. Filamentation in textured yarn
      4. iv. Yarn coming out of traverse guide
      5. v. Package webbed
    2. b. General Causes:
      1. i. Take-up tension too slow
      2. ii. Wind angle too high
      3. iii.Taper angle too low
      4. iv. Incorrect oil
      5. v. Filamentation in textured yarn
      6. vi. Radial / axial disturbance link out of phase
 

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