Yarn Conditioning Process | After Treatment of Yarn

In which process yarn is conditioned for better performance (such as strength, serviceability, luster, handle etc) is called yarn conditioning.
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 fibres and yarns. Relative humidity and temperature will decide the amount of moisure in the atmosphere. High relative humidity in different departments of spinning is not desirable. It will result in major problems. But on the otherhand, 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 fibre. 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.

The relative humidity in turn affects the properties of the fibre via the moisture content of the cotton fibre. The fibre strength and elasticity increase proportionately with the increase in humidity. If the water content of the cotton fibre is increased the fibre is able to swell, resulting in increased fibre to fibre friction in the twisted yarn structure. This positive alteration in the properties of the fibre 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.

Conditioning Process for various yarns:

1) 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.

2) 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.

3) 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.

4) Cotton/Lycra (40's Lycra) or Viscose/Lycra (60's) : Conditioning the yarn as mentioned for silk.

The following effects would be envisaged by steam-conditioning of yarn:

  • Twist Setting - Preventing Snarling (yarn loops)
  • Better Dye affinity - Eliminating static electricity
  • Influencing the Cloth handle - Preventing crease-proneness
  • High bulking - Humidifying
  • Dye - fixing - De-crinkling
  • Determining residual boiling shrinkage.
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