Sunday, 3 May 2009

Common Yarn Faults in Manmade Fibres



Common Yarn Faults in manmade fibres

1. Slubs:

Slub like thick faults seriously mar the appearance of fabrics made from manmade fibres. The following measures can be taken

A. In Blends with cotton

a. properly select the cotton component
b. ensure proper grinding of wirepoints at cards
c. regularly check the ringframe drafting system.

B. In 100% manmade fibres

a. Ensure adequate number of doublings
b. avoid too wide a roller setting and inadequate weighting on rollers.
c. Select correctly the fibres in regard to their compatibility in length.

2. Crackers

This defect is characterised by the cracking sound produced when the yarn is pulled. The sound is produced due to sudden rupture of fibres curled around the yarn.

- Crackers are caused mainly by the presence of very long fibres due to improper cutting of the two.

- They can also be caused due to high vairability in the elongation of the constituent fibres in the blend.

- Ensure wider roller setting in the back zone, adequate roller weighting and avoid too narrow a spacing between the aprons.

- It is helpful to have low roving twist and higher spinning tension through the use of heavier traveller.

3. Neps

This can also mar the appearance of a fabric

- In man made fibres longer and finer fibres tend to produce more neps.
- Other reasons of neps are
- Excessing beating of fibres in the blow room
- Loading of licker-in or cylinder at card
- Blunt wire points on various carding elements
- excessive lap weight

4. Fluffy Yarn

In general presence of short fibres and proneness to static accumulation tend to produce this defect.

The fault can be corrected by maintaining proper atmospheric conditions and reducing the fluff on roving.

5. Smoky Yarn

- The yarn containing synthetic fibres get smoky through long exposure of the running bobbin in a dirty atmosphere in the ring spinning system.

- Installation of smoke filters in H-plant can correct the problem

- Use of roving build can check this defect.


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