Introduction: Knitting yarn requires higher evenness, good softness, certain strength, extensibility, and twist. In the process of forming knitted fabric on the knitting machine, the yarn is subject to complex mechanical actions, such as stretching, bending, and twisting. , Friction, etc. In order to ensure the normal production and product quality, the knitting yarn should meet the following requirements:
1. The yarn should have certain strength and extensibility
Yarn strength is an important quality indicator of knitting yarn. Since the yarn undergoes certain tension and repeated loads during the preparation and weaving process, the knitting yarn must have a certain strength. In addition, the yarn is also subject to bending and torsion deformation during the knitting process. Therefore, the knitting yarn is required to have a certain degree of extensibility, so as to bend into a loop during the knitting process and reduce yarn breakage.
2. The yarn should have good softness
The softness of knitting yarn is higher than that of weaving yarn. Because the soft yarn is easy to bend and twist, the loop structure in the knitted fabric is uniform, the appearance is clear and beautiful, and the yarn breakage during the weaving process and the damage to the loop forming machine can be reduced.
3. the yarn should have a certain twist
Generally speaking, the twist of knitting yarn is lower than that of weaving yarn. If the twist is too large, the softness of the yarn will be poor, it is not easy to be bent or twisted during weaving, and it is easy to produce kinks, causing weaving defects and damage the knitting needles; in addition, the yarn with too large twist will affect the elasticity of the knitted fabric. , And make the coil skew.
However, the twist of the knitting yarn should not be too low, otherwise it will affect its strength, increase the breakage during weaving, and the yarn is bulky, making the fabric easy to fluff and pilling, and reduce the wearability of the knitted fabric. Therefore, the correct choice of twist is an important way to select yarns reasonably. The use of knitted fabrics is different, and the twist requirements are also different.
(1) Single jersey requires smoothness, compactness, smooth surface and clear texture. The twist of the yarn should be larger, which can be close to the warp yarn standard for weaving with the same linear density.
(2) The twist of the yarn for outer clothing should be larger to enhance the crispness and improve the phenomenon of pilling.
(3) Cotton wool cloth and elastic cloth are required to be soft and flexible, and the twist of the yarn should be slightly lower. Generally, the lower deviation of the twist of the weft yarn for weaving with the same linear density is used. The yarn used for piled knitted fabrics is to facilitate the pile, and to make the pile thickness uniform, and the twist requirement is smaller.
In addition, the amount of twist varies with yarn linear density.
4. the linear density of the yarn should be uniform and the yarn defect should be less
The uniformity of yarn linear density, that is, the uniformity of yarn evenness, is an important quality indicator of knitting yarn. Evenly even yarn is good for knitting and ensuring the quality of the fabric, so that the loop structure is uniform and the cloth surface is clear.
Yarn defect is also an important indicator of card clothing yarn. If there are thick knots on the yarn, the knitting cannot pass smoothly, resulting in yarn breakage or damage to the machine parts, and it is easy to form "stripes" and "clouds" on the cloth surface, reducing the quality of the knitted fabric; For details, the strength is insufficient here, and the ends are easily broken, which affects the quality of the fabric and reduces the productivity of the machine. Because there are multiple loop forming systems on the knitting machine to feed yarn into loops at the same time, it is not only required that the yarn thickness of each path is uniform, but also the thickness difference of the yarns between the paths must be strictly controlled, otherwise horizontal stripes will be formed on the cloth surface. Defects such as shadows reduce the quality of the fabric.
5. Yarn should have good moisture absorption
The ability of yarn to absorb moisture in the air is called hygroscopicity. The moisture absorption capacity of various fibers is very different, and the amount of moisture absorption varies with the temperature and humidity of the air. The yarn used for knitting production should have a certain degree of moisture absorption. Under the same relative humidity, the yarn with good hygroscopicity, in addition to its good electrical conductivity, is also conducive to the stability of the yarn twist and the improvement of the extensibility, so that the yarn has good weaving properties.
6. the yarn should have a good finish and a small coefficient of friction
The knitting yarn should be as free of impurities and oil stains as possible, and should be very smooth. The non-smooth yarns can damage the machine parts severely, easily damage the machine parts, and there are many flying flowers in the workshop, which not only affects the health of the workers, but also affects the productivity of the knitting machine and the quality of the fabric.