Winding Limitations 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
Reasons for Disturbing Yarn Faults 1. Machine parts - worn out or out of tolerance 2. Contamination – trash, dust, seed coat fragments 3. Foreign material
These yarn faults cause disruptions in subsequent processes – productivity and quality
Hence 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
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 Faults 1. 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.
Neps
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
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.
Long Thick
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 Thin
5. Count variations •
Faults with a length of several meters and having a mass increase / decrease of more than
Count
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.
Foreign Fibres
Yarn Fault Classification Matrix
)
%( ez is tl
u a F
Fault length in (cm)
Spectrum of Yarn Faults
+ 6 0 0% + 5 0 0% + 4 0 0%
Short Thick Places
+ 3 0 0%
L o n gT h i c k P la c e s
+ 2 0 0% +100% Imperfections
Unevenness
0
-100%
L o n gT h in P la c e s 0 .1 1
2
4
8 16 32 64
.
.
.
.
. . . .
F a u lt L e n g th ( c m )
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 Principle
1.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
Capacitive Measuring Principle 1. Electrical measuring condenser 2. Two electrodes 3. Electrical alternating voltage 4. Yarn 5. Electrical signal
Electrical signal corresponds to the yarn cross-section yarn mass
Changes of the yarn mass cause a proportional change of signal
Optical Measuring Principle 1. Infrared light source 2. Diffuser 3. Photocell 4. Yarn 5. Electrical signal
Electrical signal corresponds to the diameter of the usually round yarn
Changes in yarn diameter cause a proportional change of signal
Foreign Fiber Clearing • 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
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
