Knitting requires a higher stem (i.e.high uniformity of yarn thickness), good softness, strength and elongation, and twist (yarn twist is low). In the process of forming a knitted fabric on a knitting machine, the yarn is subjected to complex mechanical effects such as stretching, bending, twisting, and friction. To ensure proper production and product quality, yarns for knitting should meet the following requirements.
Yarn should have a certain strength and elongation
The strength of the yarn is an important quality indicator for knitting yarns. Since the yarn is subjected to certain tensions and repeated loads during preparation and weaving, yarn must have a certain strength. In addition, the yarn is subjected to bending and twisting deformation during the knitting process, so it is also required to have a certain elongation to facilitate the bending of the yarn into a loop and to reduce yarn breakage.
Yarn should have good flexibility
The softness of knitting yarns is higher than that of woven yarns. Because soft yarn is easy to bend and twist, and make the loop structure in knitted fabric even, clear and beautiful appearance, and softy yarn also can reduce the breakage and damage to the looped machine parts during the weaving process.
Yarn should have a certain degree of twist
Generally speaking, knitting yarn has a lower twist than weaving yarn. If the twist is too high, the yarn will be less soft and less likely to be bent or twisted during knitting, and yarn will easily produce kinks and cause faults and damage to knitting needles. In addition, a yarn with too much twist will affect the elasticity of the knitted fabric and make the loop crooked. However, the twist of knitting yarn should not be too low, otherwise it will affect its strength and increase the breakage of knitting, and the yarn will be puffy, making the fabric easy to pilling and reduce the taking performance of knitted fabric. Therefore, the correct choice of twist is an important way to reasonably choose the yarn. Knitted fabrics have different applications and different twist requirements.
For sweat cloth, which requires smoothness, tightness, surface finish and clear pattern, the twist of the yarn should be larger and can be close to the standard of warp yarn for weaving with the same line density.
The twist of yarn for outerwear should be larger to enhance the stiffness and improve the pilling phenomenon. Cotton woolen cloth and elastic cloth requires a soft feel and elasticity, the twist of the yarn should be slightly lower, generally using the same line density of weft yarn twist deviation.
For pile knitted fabric yarn, in order to facilitate the pulling of the pile, and make the pile head thickness uniform, twist requirements are smaller.
In addition, the size of the twist also varies with the yarn density.
Uniformity of yarn density and few defects
The uniformity of yarn density is an important quality indicator for knitting yarn. A uniform yarn is good for the knitting process and for the quality of the fabric, so that the loop structure is uniform and the fabric surface is clear.
If the yarn has coarse knots, the knitting will not pass smoothly, it will result in yarn breakage or damage to the machine, and it is easy to form “horizontal strips” and “cloud spots” on the fabric surface, reducing the quality of the knitted fabric.If the yarn has thin knot , it is not strong enough here and easy to break the head, it will affect the quality of the fabric and reducing machine productivity.
Because the knitting machine has a multi-way loop system at the same time into the yarn into the loop, so not only require each way yarn thickness uniform, and the difference between the yarn thickness between the road also need to be strictly controlled, otherwise yarn will form on the surface of the cloth horizontal stripes, shadows and other defects, reducing the quality of fabric.
Yarn should have good moisture absorption
The ability of yarn to absorb moisture in the air is called moisture absorption. The ability of various fibers to absorb moisture varies greatly, and the amount of moisture absorption varies with the temperature and humidity of the air.
Yarn used for knitting production should have a certain moisture absorption. Under the same relative humidity condition, the yarn with good hygroscopic property can not only have better electrical conductivity, but also help to improve the stability of yarn twist back and the elongation, so that the yarn has good knitting performance.
Yarn should havegood smoothness and small coefficient of friction
Yarn for knitting should be as free as possible of impurities and oil stains, etc., and should be very smooth. That is not smooth, the friction of the machine is strong, easy to damage the machine, will be in the workshop products flying fibers, Both affecting the health of workers, but also affect the productivity of the knitting machine and the quality of the fabr
