WindingLimitations of Spinning Technology Progress in spinning – automation and productivity Despite of progress, it is still not possible to produce a

fault-free yarn Depending on the raw material and state of the

machinery park, there are about 20 to 100 events over a length of 1000 km yarn

Yarn exhibits a yarn faults every 1 to 5 km. Yarn faults – too thin, too thick, foreign fibre and dirty

places Spinning process leads to formation of disturbing

faults

1. Machine parts - worn out or out of tolerance

2. Contamination – trash, dust, seed coat fragments

3. Foreign materialThese yarn faults cause disruptions in subsequent

processes – productivity and qualityHence spinner has to fulfill the demand of fault free

yarn by two measures

1. Prevent origin of yarn faults by adequate measure- Choice of raw material, m/c maintenance and cleanliness in

mill

2. Remove yarn faults by the aid of yarn clearers - Winding process

Reasons for Disturbing Yarn Faults

Winding Machine

Objects of Winding:

1. Extraction of disturbing yarn faults

2. Conversion of smaller package to bigger

package

3. Waxing of the yarn during winding process

4. Clearing foreign fibres

5. Clearing of Polypropylene

6. Detection of off-standard bobbins

7. Monitoring frequent yarn faults

8. Monitoring & documentation of quality data

Passage of Yarn through Winding Machine

Yarn Faults

Textile industry is dividing the yarn faults in

1. Frequently occurring faults

- Tested on Evenness Tester

- Expressed per 1000 m of yarn

2. Seldom occurring defects

- detected & eliminated during winding

- expressed per 1,00,000 m of yarn

Difference between Frequent faults & Seldom occurring

defects is mainly larger mass or diameter deviation and size

Classification of Yarn Faults1. Neps• Faults that are less than 1cm and having a mass

increase of more than 100% are called Neps

• They are basically produced due to immature fibres / seed coat fragments in the raw material, very short entanglements of fibres and yarns.

2. Short Thick Places• Faults with a length of 1 cm to 8 cm and having

a mass increase of more than 100%

• These faults are basically produced due to short

fibres, improper draft control, bad piecing, flies in spinning

Neps

Short Thick

3. Long Thick Places• Faults with a length of more than 8 cm and

having a mass increase of more than 45% are called Long Thick places.

• These faults are basically produced due to thick places in sliver, roving etc.

4. Thin Places• Faults with a length of more than 8 cm and

having a mass decrease of more than 30% are called Thin places

• These faults are basically produced due to missing sliver in drawing, stretches in sliver and roving etc.

Long Thick

Long Thin

5. Count variations

• Faults with a length of several meters and

having a mass increase / decrease of more

than 5% are called count variations

6. Foreign matters

• Faults with a length of more than 1 mm and

visibility level of more than 5% are called

foreign matters

• They are primarily produced due to mix up

of colour fibres, jute, hair, seed particles etc.

Count

Foreign Fibres

Yarn Fault Classification Matrix

Fault length in (cm)

Fau

lt s

ize

(%)

Spectrum of Yarn Faults

Fault Length (cm)-100%

0

+100%

+200%

+300%

+400%+500%+600%

0.1 21 4 8 16 32 64 . . . . . . . .

Unevenness

Imperfections

Short Thick Places

Long Thick Places

Long Thin Places

Basic setting of N S L T For an easy setting of clearing limits Thick places are divided in to

NSL classes and Thin place expressed as T N – channel - Less than 1 cm (to clear nep faults)

S – channel – 1.0 to 8.0 cm (to clear short thick place faults)

L - channel – up to 200 cm (to clear long thick place faults)

T - channel – up to 200 cm (to clear thin place faults)

Class Clearing Curve

Electronic Yarn Clearing

Yarn Faults Removing Principle1.Yarn faults monitored by an

electronic device

2.As soon as yarn clearer detects a

yarn fault, the yarn will be

separated by the cutter

interrupting winding

3.Yarn fault removed by the suction

of the winding machine

4.Yarn splicing or knotting

5.Winding process continues up to

next fault

Yarn Fault Measuring Principle• Thickness of the yarn monitored and converted into a

proportional electrical voltage signal• Sensor monitors a yarn running up to 120 km/hr and , the

yarn is measured every 2 mm• Signal conversion is carried by – Capacitive measuring principle or Optical measuring principle

1. Electrical measuring condenser

2. Two electrodes

3. Electrical alternating voltage

4. Yarn

5. Electrical signal

Capacitive Measuring Principle

Electrical signal corresponds to the yarn cross-section yarn mass

Changes of the yarn mass cause a proportional change of signal

1. Infrared light source

2. Diffuser

3. Photocell

4. Yarn

5. Electrical signal

Optical Measuring Principle

Electrical signal corresponds to the diameter of the usually round yarn

Changes in yarn diameter cause a proportional change of signal

• Cotton can be contaminated the cotton field to the spinning mill

• Human and animal hair, feathers, strings, packing material, stems, leaves and oil stains

• Foreign fibers –cause fabric defect, lower the efficiency of the following processes

Foreign Fiber Clearing

Detection of Foreign and Polypropylene Fibers

• Optical measuring system

• Comparison between the reflection of the foreign fiber and the normal yarn color

Classification Matrix - Uster

Classification Matrix - Loepfe