Knitting requires higher dryness (that is, the uniformity of the thickness of the yarn), good softness, a certain strength, elongation, and twist (yarn twist is relatively low). In the process of forming knitted fabrics on the knitting machine, the yarns are subject to complex mechanical effects, such as stretching, bending, twisting, friction, etc.In order to ensure the normal progress of production and the quality of the product, the yarn used for knitting should meet the following requirements：

1. The yarn should have a certain strength and extensibility

The strength of the yarn is an important quality index of the yarn used for knitting.Since the yarn is subjected to certain tension and repeated loads during the preparation and weaving process, the yarn for knitting must have a certain strength.In addition, the yarn is subject to bending and torsional deformation in the process of weaving into circles, so it is also required that the knitting yarn has a certain extensibility in order to bend into circles during the weaving process and reduce yarn breakage.

2. The yarn should have good softness

The softness of knitting yarn is higher than that of woven yarn.Because the soft yarn is easy to bend and twist, the coil structure in the knitted fabric is uniform and the appearance is clear and beautiful. At the same time, it can also reduce the broken ends of the yarn during the weaving process and the damage to the circled parts.

3. The yarn should have a certain twist

Generally speaking, the twist of knitting yarn is lower than that of woven yarn.If the twist is too large, the softness of the yarn is poor, it is not easy to be bent or twisted during weaving, and it is also prone to kink, causing weaving defects and damage to the knitting needle; in addition, the yarn with too large twist will affect the elasticity of the knitted fabric and skew the coil.However, the twist of the yarn used for knitting should not be too low, otherwise it will affect its strength, increase the breakage during weaving, and the yarn will swell, making the fabric easy to fluff and pilling, and reducing the wear resistance of the knitted fabric.Therefore, the correct choice of twist is an important way to choose yarn rationally.The uses of knitted fabrics are different, and the twist requirements are also different.

Jersey requires smooth, tight, smooth surface, clear lines, and a larger twist of yarn, which can be close to the standard of warp yarns for weaving with the same linear density.The twist of the yarn used for outerwear should be larger to enhance the stiffness and improve the phenomenon of pilling.Cotton wool cloth and elastic cloth require softness and elasticity to the touch, 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.Yarn for fleece knitted fabrics, in order to facilitate the drawing of the fleece and make the thickness of the fleece uniform, the twist requirements are smaller.

In addition, the size of the twist also varies with the linear density of the yarn.

4. The linear density of the yarn should be uniform and the yarn defects should be less.

The uniformity of yarn linear density, that is, the uniformity of the dryness of the yarn, is an important quality index of yarn for knitting.Evenly dried yarns are conducive to knitting processing and ensuring fabric quality, so that the coil structure is uniform and the cloth surface is clear.If there are thick joints on the yarn, the weaving will not pass smoothly, causing the yarn to break or damage the machine parts, and it is easy to form “horizontal bars” and “cloud spots” on the cloth surface, reducing the quality of the knitted goods; if there are details on the yarn, the strength is insufficient here, it is easy to break the head, affecting the quality of the fabric and reducing the productivity of the machine.Because there is a multi-channel winding system on the knitting machine that enters the yarn into a circle at the same time, it is not only required that the thickness of each yarn is uniform, but also that the thickness difference between the yarns must be strictly controlled, otherwise it will form horizontal stripes, shadows and other defects on the cloth surface, reducing the quality of the fabric.

5. The yarn should have good moisture absorption

The ability of yarns to absorb moisture in the air is called hygroscopicity.The moisture absorption capacity of various fibers varies greatly, and the size of the moisture absorption varies with the temperature and humidity of the air.The yarn used in knitting production should have a certain moisture absorption.Under the same relative humidity conditions, yarns with good moisture absorption, in addition to their good electrical conductivity, are also conducive to the stability of yarn twisting and the improvement of elongation, so that the yarns have good weaving properties.

6. The yarn should have a good finish and a small coefficient of friction.

The yarn for knitting should be as free of impurities and oil stains as possible, and it should be very smooth.Non-smooth yarns have severe friction on the parts, which can easily damage the 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.