Saturday, December 31, 2016

Yarn Faults in Spinning | Common Types of Yarn Faults

Yarn Faults:
Yarn faults are very important characteristics which affecting spun yarn ability process and fabric appearance. Not only affect the appearance of fabric but also create hamper in spinning operation. Thick places in yarn are often caused by soiling or damaged machine parts. Thin places can occur, excessive drafts in the drafting assembly. Yarn faults are responsible for rejection and down grading of yarn and low productivity due to higher end breakage in further process. If yarn quality become poor then it is not possible to make good quality fabric. So, maintaining yarn defects are very important for spinners.
Various types of yarn faults
Fig: Various types of yarn faults
It is still not possible to produce a yarn without faults though you use the most sophisticated spinning machineries but it is difficult to produce defect free yarn due to the lacking in the manufacturing processes and raw material quality.

Types of Yarn Faults:
There are various types of yarn faults. Yarn faults are defined according to their length and width. The length is specified in centimeters and the width as multiple of the normal diameter of a yarn.

We can classify yarn faults according to causes of time:
  1. Frequently Occurring Faults( Analyzed by Uster Evenness Tester)
  2. Seldom Occurring Faults( Scanned by Uster Classimat Tester)
1. Frequently occurring faults:
Frequently occurring faults include thick and thin places, neps which are measured by evenness tester. These faults occur in the range of 10-5000 times per 1000 meters.

2. Seldom occurring faults:
These types of faults include slubs, spun in fly, long thin places in yarn. Seldom occurring faults for at least 100 km of the yarn. The seldom occurring faults can be grouped into four main types, viz. Short thick, long thick and long thin faults.

We can also can get idea about classification of yarn faults.
Classification of yarn faults
Fig: Classification of yarn faults
Common Types of Yarn Faults:
Following types of yarn faults occur in different process of spinning.
  1. Neps
  2. Slub
  3. Sarl
  4. Thick and thin places
  5. Soft yarn/loose yarn
  6. Oil Stain yarn
  7. Crackers
  8. Bad piecing
  9. Oily slub
  10. Kitty yarn
  11. Hairy yarn
  12. Foreign matters
  13. Spun in fly
  14. Cork screw yarn
  15. Slough Off
  16. Knots
  17. Excessive Hard Yarn
  18. Rust Stain
  19. Low Strength of Yarn
Though faults free yarn is not possible to manufacture. But many of these faults can be avoided by keeping the spinning machine clean as well as using optimized settings. If cotton quality become good then also possible to produce comparatively less faulty yarn.