What is Yarn Conditioning?
The ultimate concept of the yarn conditioning process is to supply the yarn with increased strength and elongation, reduced snarling of yarn, improved working at post spinning processes like warping, weaving, knitting, etc.
Textile fibers are subjected to various physical operations to make in to a yarn. For example cotton fiber passes through opening, carding, drawing and spinning to become a yarn. During these phases the original moisture content on the fiber would have been lost and some static electricity would be carried by the fiber. The amount of static current carried by yarn changes from fiber to fiber. Similarly the strength of any fiber depends up on how close the present moisture content is to the original natural value.
Similarly some high twist yarn would tend to loose its twist as and when it is allowed freely, making a lengthwise elongation.
Some fibers would tend to shrink when exposed to hot atmosphere or any treatment that involves heat and hence higher temperature. For example polyamide, polyester etc. Some blends like Cotton/Lycra, Viscose/Lycra require conditioning to make the width the fabric stable. So all the above said factors, if not addressed properly would reflect badly on the final quality of yarn or fabric.
Moisture in atmosphere has a great impact on the physical properties of textile fibers and yarns. Relative humidity and temperature will decide the amount of moisture in the atmosphere. High relative humidity in different departments of spinning is not desirable. It will result in major problems. But on the other hand, a high degree of moisture improves the physical properties of yarn. Moreover it helps the yarn to attain the standard moisture regain value of the fiber. Yarns sold with lower moisture content than the standard value will result in monetary loss. Therefore the aim of conditioning is to provide an economical device for supplying the necessary moisture in a short time, in order to achieve a lasting improvement in quality.
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The relative humidity in turn affects the properties of the fiber via the moisture content of the cotton fiber. The fiber strength and elasticity increase proportionately with the increase in humidity. If the water content of the cotton fiber is increased the fiber is able to swell, resulting in increased fiber to fiber friction in the twisted yarn structure. This positive alteration in the properties of the fiber will again have a positive effect on the strength and elasticity of the yarn.
A process that addresses all the above parameters is called conditioning. Conditioning process differs from fiber to fiber. So conditioning is a preliminary process in any processing that improves and maintains the quality of yarn.
Conditioning may be done in yarn stage on perforated paper or plastic cones/cheeses in an Auto Clave or Horizontal beam dyeing machine as shown above.
Sometimes yarn conditioning prior to weaving is required. Yarn exposure to the room air during the weaving process is as short as 15 min. or less. The weaving process would run best with a very high room humidity level in the range 85–95%, but operator comfort imposes a limit, usually of 60–65%. Room temperature is normally kept within the range 24–26°C. Therefore, the concept of localized humidification is beneficial.
Types of Yarn Conditioning:
Yarn conditioning at the end of spinning processes is mostly done by using steam. But another option of conditioning is available which is mostly used in different spinning processes to control humidity and temperature is to use humidifiers. Humidifiers are very less used for yarn conditioning at the end of spinning. So, conditioning has two types:
- Conditioning by steam
- Conditioning by humidifiers
Conditioning Process for Various Yarns:
- 100% Polyester yarn: Load the yarn in the form cones wound on plastic cones, in to a beam dyeing machine. Introduce steam and raise the temperature to 100°C at 3°C per minutes. Steam for 15 minutes at 100°C followed by 15 minutes cooling = 1 cycle. Repeat the cycle for 4 times.
- 100% Nylon: Load the yarn in the form cones wound on plastic cones, in to a beam dyeing machine. Introduce steam and raise the temperature to 100°C at 3°C per minutes. Steam for 15 minutes at 100°C followed by 15 minutes cooling to a temperature of 50°C = 1 cycle. Repeat the cycle for 4 times.
- Silk yarn: Load the yarn in the form cones wound on plastic cones, in to a beam dyeing machine. Introduce steam and raise the temperature to 70°C at 3°C per minutes. Steam for 15 minutes at 70°C followed by 15 minutes cooling to a temperature for 30°C = 1 cycle. Repeat the cycle for 4 times.
- Cotton/Lycra (40’s Lycra) or Viscose/Lycra (60’s): Conditioning the yarn as mentioned for silk.
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Benefits of Yarn Conditioning:
- Increase in moisture content of yarn that enhances the mechanical properties of yarn
- Reduction in fluff and fly generation in subsequent processes such as weaving and knitting up to 30%–50%
- Reduction in needle breaks in knitting process up to 35%
- Improvement in machine efficiency in weaving and knitting
- Improvement in uniformity and appearance of the yarn
- Reduction of electrostatics effects
- Reduces the visible loss to the spinner by increasing yarn weight
- Reduces the wear and tear of needle at knitting machine
- Reduction in end breakage in weaving and knitting
- Increases softness of cloth
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Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
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