Knitting requires higher evenness (that is, the uniformity of the thickness of the yarn), good softness, certain strength and extensibility, Twist (yarn twist is relatively low) In the process of forming knitted fabrics on a knitting machine, the yarn is subject to complex mechanical effects, such as stretching, bending, torsion, friction, etc. In order to ensure the normal production and product quality, knitting yarn should meet the following requirements:
The yarn should have a certain Strength and extensibility
The strength of yarn is an important quality indicator of knitting yarn. Since the yarn is subjected to a certain amount of tension and repeated loading during preparation and weaving, the yarn used for knitting must have a certain strength. In addition, the yarn is also subject to bending and torsional deformation during the knitting process, so the knitting yarn is also required to have a certain extensibility to facilitate bending into loops during the knitting process and reduce yarn breakage.
The yarn should have good softness
The softness of knitting yarn is higher than that of weaving yarn. Because soft yarn is easy to bend and twist, it can make the loop structure in knitted fabrics uniform and clear and beautiful in appearance. It can also reduce yarn breakage and damage to knitting machine parts during the weaving process.
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, and it will be difficult to bend and twist during weaving. It will also easily produce kinks, causing weaving defects and damaging the knitting needles. In addition, the yarn with too much twist will affect the elasticity of the knitted fabric. , causing the coil to skew. However, the twist of the knitting yarn cannot be too low, otherwise it will affect its strength, increase breakage during weaving, and make the yarn bulky, making the fabric prone to pilling and reducing the wearing performance of the knitted fabric. Therefore, the correct selection of twist is an important way to rationally select yarn. Knitted fabrics have different uses and different twist requirements.
Jersey cloth requires smoothness, tightness, smooth surface, and clear texture. The twist of the yarn should be larger, which can be close to the same linear density woven warp standard. The twist of the yarn used for outerwear should be larger to enhance the stiffness and improve the pilling phenomenon. Cotton fabrics and stretch fabrics are required to feel soft and elastic, and the twist of the yarn should be slightly lower. Generally, the lower deviation of the twist of the weft yarn used for weaving with the same linear density is used. The yarn used for fleece knitted fabrics is to facilitate brushing and make the pile thickness uniform, and the twist requirement is smaller.
In addition, the degree of twist also varies with the linear density of the yarn.
The yarn should have uniform linear density and few yarn defects
Yarn linear density uniformity That is, the uniformity of yarn stems is an important quality indicator of knitting yarn. Uniform yarn is beneficial to knitting processing and ensures fabric quality, making the loop structure uniform and the cloth surface clear. If there are thick spots on the yarn, the knitting will not be able to pass smoothly, causing yarn breakage or damage to the machine parts, and “horizontal stripes” and “cloud spots” will easily form on the cloth surface, which will reduce the quality of the knitted fabric; if there are thick spots on the yarn Details, the strength is insufficient here and ends are easy to break, affecting the quality of the fabric and reducing machine productivity. Because there are multiple loop-forming systems on the knitting machine that feed yarn into loops at the same time, not only is the yarn thickness of each loop required to be uniform, but the difference in yarn thickness between each loop must also be strictly controlled, otherwise horizontal stripes will be formed on the cloth. Defects such as shadows reduce fabric quality.
Yarn should have good hygroscopicity
The ability of yarn to absorb moisture in the air is called hygroscopicity. The moisture absorption capabilities of various fibers vary greatly, and the amount of moisture absorption varies with the temperature and humidity of the air. Yarn used in knitting production should have certain hygroscopicity. Under the same relative humidity conditions, yarns with good hygroscopicity, in addition to their better electrical conductivity, are also conducive to the stability of the yarn twist and improvement of extensibility, so that the yarn has good weaving performance.
The yarn should have good smoothness and a small friction coefficient
Knitting yarn should be as free from impurities and oil stains as possible etc., and should be very smooth. Unsmooth yarns cause severe wear and tear on machine parts and are easy to damage machine parts. There are also many flying flowers in the workshop, which not only affects the health of workers, but also affects the productivity of knitting machines and the quality of fabrics. </p
