Where can I find the quality index of knitting yarn?

In the process of circular knitting, the yarn is subjected to many complicated mechanical actions. For example, when knitting into a circle, it will be deformed by stretching, bending and twisting. At the same time, when the yarn passes through the yarn guide device and its coil, it will be subjected to different forms of friction. Therefore, the quality of yarn has a great influence on the output of circular knitting machine and the quality of grey cloth. The main quality indexes of yarn are briefly introduced below.

First, the strength of yarn, in layman's terms, refers to the "fastness" of yarn. Because the yarn is subjected to certain tension and load in the production process, the yarn must have certain strength to ensure the normal knitting process. The strength of yarn can be measured by a single yarn strength machine, which is generally expressed by breaking strength (the force used at the moment when the yarn breaks on the strength machine, the unit is CN/tex(gf/tex). The strength of yarn is related to the kind, thickness, twist, uneven count and quality of yarn fiber.

Second, evenness refers to the degree of yarn thickness uniformity. The thickness of yarns with the same count should be uniform in theory, but in the spinning process, due to the influence of operation and technology, the thickness of yarns is uneven. Yarn with uneven thickness will produce horizontal stripes on the surface of grey cloth, which will affect the quality of grey cloth. Yarn evenness is one of the important quality indexes of yarn.

Third, yarn defects refer to defects on cotton yarn. For example, roving, colored yarn, neps, impurities, oil yarn, rust spots and so on. Yarn defects on cotton yarn can be measured by a yarn defect instrument. In the production process, yarn defects will be directly brought to the cloth surface, which will affect the quality of the cloth surface.

In spinning (spinning frame), the yarn is stretched and stretched at the same time. The purpose of stretching is to make the yarn have better strength. There are two drawing directions of yarn: Z drawing and S drawing. S-stitch (also called reverse stitch) is often used in knitting mills. When the yarn is too high, it is not easy to bend in knitting production, and it is easy to twist and knit the yarn, which will reduce the elasticity of the fabric and easily form braids on the surface of the fabric. In addition, the loop forming part of circular knitting machine is also easy to be damaged where the yarn passes. Too low yarn will affect the yarn strength, increase the broken end rate of circular knitting machine, increase the labor intensity of the car stopper of circular knitting machine and reduce the output. Too many knots will affect the quality of fabric. Generally speaking, cotton yarn used in knitting factories has lower twist requirements than woven yarn, because knitted products require soft and bulky feel. Yarn twist can be measured by a twist tester.

5. When the yarn is stretched on the strength machine, it will be stretched until it breaks. The percentage of the stretched length to the original length is called the elongation of cotton yarn. Cotton yarn with good elongation can buffer the action of external force in the production process and reduce the broken end rate.

Good quality cotton yarn, its color is white and bright. The color of cotton yarn is related to the quality of cotton itself and the grade of cotton blending. For example, cotton with poor maturity has many spinning knots; The color of over-ripe cotton is poor, and there are more dead cotton (uncolored) on the woven grey cloth. Knitting yarns should have colors that meet the quality requirements, especially cotton yarns used for dyeing yarns, which require higher colors.

Seven, other indicators of other yarns are hairiness.