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Whilst in the spinning plant the moisture content can
be controlled continuously, the moisture evolution is
totally out of control during the stocking and transporting
period. Therefore, it is imperative for a good quality
management to ensure that the yarn leaves the spinning
plant with an appropriate degree of moisture. The better
the moisture level, the better will be the workability
of the yarn in weaving or knitting. Often, the moisture
level is the "forgotten quality criteria".
Therefore, moisture regain becomes essential in the textile
industry. High speed spinning machines generate more friction
thus giving additional heat to the yarn. As a result of
such heat transfer the yarn moisture content is vaporised
and disappears.
| It is well known that dry yarns have worse properties
in subsequent processing. Rising speeds in spinning
result in decreased yarn quality for other processes.
For quality reasons, it is absolutely important to
have an even distribution of this |
Influence of the
parameters on the conditioning results
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recuperated moisture throughout the entire yarn package.
Conditioning room or vacuum technology?
Only the vacuum technology provides
moisture regain with the appropriate evenness of distribution.
Traditional conditioning rooms are obsolete for both
economic and quality reasons. High residual times
of up to 24 hours, energy consumption and space requirements
with high investment costs in line with a bad moisture
distribution are their main disadvantages. Welker
provide state-of-the-art conditioning systems for
economic and efficient moisture regain to improve
yarn quality. |
Cold saturated steam process |
The variables
Looking superficially, the vacuum technology appears to
be quite simple. However, the moisturising quality is
primarily influenced by the equipment and its resources
to provide appropriate results. Variations in process
temperature, moisture distribution and moisture level
have direct influence on the yarn quality.
If the interdependence of these elements is not observed
in production, the moisture efficiency will not be satisfying
and the quality will not be sufficient.
The better the vacuum, better the
yarn treatment
There is an obvious interdependence between the vacuum
and the penetration of saturated steam. Additionally,
the deeper the pressure, the lower the boiling point
of water and therefore, the smoother will be the treatment
of yarn at 95% vacuum (High vacuum), the process starts
at 32.9°C and rises continuously up to the recommended
final temperature. By this phenomenon, systems with
vacuum rates above 90% can provide better results
than others with less vacuum.
Saturated steam |
Better Vacuum leads to better
yarn treatment*-*
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All conditioners work with saturated steam under
vacuum. This steam is an invisible gas and is very
appropriate for the treatment of cops, bobbins and
fabrics. Saturated steam is formed between 18°C
in 98% vacuum and 99.7°C at atmospheric pressure.
Conditioning with saturated steam
Vacuum generated by high-performance pumps initiates
the conditioning cycle inside the autoclav, exhausting
the existing air, Due to the vacuum pressure, the
saturating point of steam decreases at very low
boiling levels.
Feeding in a given quantity of heated water, immediately
an atmosphere of low temperature saturated steam
is formed in equilibrium with vacuum. The deep vacuum
makes steam to penetrate deeply into the yarn packages.
The temperature difference between steam and yarn
causes steam to condense inside the yarn package.
Moisture is absorbed by the yarn and the package
is heated up.
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At the end of cycle, the last phase of conditioning takes
place. A sophisticated air saturating system applies a
finishing spray to the yarn bobbins in combination with
the depressurising of the machine. With this exclusive
device, better conditioning results can be achieved. Prior
to packaging the yarn needs to be cooled down after the
conditioning cycle for approx. 20-40 minutes, depending
on the temperature and climate.
Applications
Welker conditioning systems are designed for moisturising
in the temperature range between 50 and 70°C. Due
to the soft starting temperature of 20.0°C, they are
ideal for conditioning of waxed yarns. We recommend to
use waxes with melting points between 60 - 65°C.
Welker Conditioning Systems also allow heat setting at
temperatures up to 95°C, thus offering an excellent
price/performance ratio.
· Pressure Range: -1 bar to 0 bar
· Temperature Range: 45° to 95°C
Advantages of conditioning
For spinning mills
· Increase of the moisture content of the yarn,
thus compensating the loss of water during the spinning
process
Increase of yarn quality, thus providing a better market
position against competitors with dry yarns.
For knitting mills:
· Reduction of fly and dust up to 50%
· Decrease of needle breaks up to 25-35%.
· Increase of efficiency up to 10% by decrease
of thread tension and machine down-times
· Support of dimensional stability of knitted goods.
· Improvement of feel and volume of the goods
· Improvement of friction values
· Improvement of uniformity of the goods by improved
appearance
· Reduction of electrostatic
effects.
For weaving mills:
· Reduction of fly and dust up to 30-40%
· Decrease of thread breaks during the weft
insertion, depending on the insert system, up to 15%
· Increase of efficiency up to 2%
· Improvement of feel and volume of the goods
· Improvement of friction values
· Improvement of uniformity of the goods
· Further improvement of efficiency, if conditioned
yarn is used in warping room.
Courtesy: Welker GmbH |
Differnt Yarn applications
by Welker Conditioning systems
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