The goal of sizing is to join the fibres and coat the yarn to enhance strength and abrasion resistance while also making it smooth and uniform. This may be accomplished by various mechanical procedures such as dipping the yarn in size paste and drying. The yarn sizing process employed is determined by the scale on which the warp yarn is required for weaving. When just a tiny scale is necessary, the hank sizing method is used. This method is primarily used by hand loom weavers in India. Ball warp yarn scaling, also known as chain warp sizing, is a somewhat sophisticated method used when a little bigger scale sized warp is required. This approach is rarely seen in our nation, although it was popular in Europe when spinning mills offered yarn in the shape of a sized warp ready for weaving. However, slasher sizing or tape size is the most widely used yarn sizing technique all over the globe.
Yarn sizing Process
The most essential phrase in weaving technique is sizing. During beam preparation, Yarn is sized after winding and warping. Sizing is accomplished by adding various size materials to the yarn. The application of sizing materials necessitates the use of steam. Sizing is a protective measure. Sizing is the process of adding a protective adhesive covering on the surface of the yarn. This is the most important step in attaining maximum weaving efficiency, especially with mixed and filament yarns. Sizing is referred to as the “heart of weaving.”
Sizing is done during beam preparation in order to get some weaving advantage. Sizing encompasses a wide range of items, some of which are listed below:
- To increase the weave ability of warp yarn by making it more resistant to weaving actions such as absorption, friction, tension, and so on.
- To preserve high fabric quality by decreasing hairiness and frailty while enhancing yarn smoothness and absorbency.
- Sizing increases the tensile or breaking strength of cellulose yarn.
- The yarn’s elasticity is also enhanced. The weight of the yarn is enhanced by adding larger materials.
- To improve frictional resistance.
- This procedure removes projected filaments.
- Reduce the development of electrostatic charges.
Sized yarn properties: Size components are often employed in warp yarn, although they can also be utilised in weft yarn. In any case, the following qualities are produced by applying size components to the yarn.
- Higher elasticity
- Higher yarn strength
- Lower flexibility
- Lower extension or elongation
- Lower frictional resistance
- Increased smoothness
- Less weakness Insensible to over drying
- Less hairiness
As a result, size components alter the physical characteristics of cellulosic fibres, which are utilised to create a weavers beam.
Necessity of sizing:
The interlacement of warp and weft is accomplished with the use of a machine known as a loom. On the loom, several motions are given to carry out the interlacement. Because the motions employed on the loom are numerous, they are categorised into three groups: major, secondary, and auxiliary motions. This action puts numerous pressures and strains on the warp yarn, which tends to break it. When a broken end loom needs to be halted. This decreases machine efficiency and output, increases the workload on weavers, and results in cloth of sub standard quality. Thus, in order to judge the weavability of warp, a commonly accepted criterion is the warp breakage rate, which is generally due to the various stresses that are imposed on warp during the textile weaving process. The primary goal of the entire process is to reduce the warp end break, which will weave a quality fabric with maximum loom efficiency.
Different fibers, different sizes:
The resistance of yarns to the various stresses and strains mentioned above is not the same for all fibres; nevertheless, different fibres react differently to these stressors. Silk and continuous filament manufactured fibres, for example, have high cohesion due to the continuity of the filaments and exhibit good elastic behaviour when subjected to cyclic extension. As a result, these yarns should be protected primarily against abrasion rather than cyclic extension. Wool fibres are very extensible but have poor tenacity, whereas flax and jute have great tensile strength but low elongation at break and relatively limited resistance to cyclic extension. Thus, the toughness of yarns, rather than its strength or elongation, is more significant than its strength or elongation alone.
Precautions of sizing process:
During the sizing procedure, the following measures should be taken:
- Tension on the beams should be kept to a minimum.
- Beam alignment must be done correctly.
- The temperature of the sow box should be between 80 and 85 degrees Celsius.
- It is necessary to calculate the condensation percentage of steam in the sow box. It should be kept to a bare minimum. A high steam condensation percentage might have a negative impact on the refractometer value of size liquid and dilute it.
- The level of sizing liquor in the sow box should be adequate to ensure continuous liquor circulation.
- The viscosity of the liquor should be kept as low as possible.
- The temperature of the first cylinder should be greater, while the temperature of the last cylinder should be lower.
- Always utilise a water eliminator in the sow box’s steam line.
- To avoid using an excessive quantity of sizing liquor, the squeezing pressure should be correctly set.
- Stretch percentages should be kept as low as feasible.
- The moisture percentage in the sized warp sheet should be around 8 – 9 percent.
- During the size process, the machine should not be halted for an extended period of time, since this may produce sizing liquor markings on the warp sheet, resulting in end breakage.