Knitting enterprises’ requirements for yarn quality
Knitting is divided into two categories: warp knitting and weft knitting. Cotton yarn is mainly used on weft knitting machines. Weft knitting is a weft knitted fabric. The yarn is sent to the loop knitting area of the knitting machine with a certain tension wheel, and is bent into loops and strung together to form a knitted fabric. From a weaving perspective, the yarn count is required to be soft and smooth, with appropriate and uniform twist, a certain strength and elongation at break, uniform evenness, and fewer details. Because the structure of knitted fabrics is relatively loose, there are many gaps between yarns, and uneven raw yarns directly affect the appearance of the fabric, and details are more harmful. There should be less flying flowers.
The main problems currently existing in knitted yarn
The quality and performance of knitted fabrics depend on the performance of knitted raw materials, the structure and specifications of knitted fabrics, dyeing and post-processing Organizing and other factors. Among them, the performance of knitted raw materials is the main factor affecting the properties of knitted fabrics. Knitted fabrics have different uses and different raw materials. At present, most knitted fabrics for underwear are made of cotton yarn; the raw materials of hosiery products are cotton yarn, wool and chemical fiber; wool sweaters are mainly made of wool, acrylic fiber, acrylic blended yarn, etc.; the main raw materials of knitted outerwear are polyester, nylon, acrylic fiber and blended yarns. Yarns and new textile materials (such as tencel fiber, differentiated fiber, etc.); raw materials for special industries are mainly glass fiber, metal wire, aramid fiber, etc. The raw material components can be pure spinning yarn containing only one fiber or blended yarn with two or more fibers; (such as colorful yarn, slub yarn, knot yarn, core-spun yarn, etc.). In addition, the emergence of new raw materials such as chemical fiber special-shaped fibers, composite fibers, especially ultra-fine denier fibers, has opened up new ways for knitting yarns.
The yarn count tested in the laboratory basically reaches the first-class level. Only carded yarn has more neps and impurities, and a few twist coefficients exceed 360. The second is uneven dryness, which is not reflected in the blackboard dryness. The 0.9.1.0 blackboard will have more cloudy shadows on the actual object. This has happened whether it is carded or combed, and even long-staple cotton yarn has appeared. The third is foreign fibers, both carded and combed. Foreign fiber yarn can only be covered by dyeing products. Fourth, neps have white spots and uneven coloring, which is more prominent on carded yarns and uneven coloring on blended yarn fabrics. The fifth is hairiness. Cotton yarn has a lot of hairiness, and there are many floral patterns during weaving. If the floral patterns are rolled in, it is a weaving defect. Bad needles, rough finished fabrics, and cloth surface are hairy and not smooth.
The quality requirements of knitting enterprises for yarn count
In a large weft knitting machine, more than 100 yarns are fed into the knitting machine at the same time. If there is a slight deviation, it will be The surface of knitted fabrics is exposed, especially single-sided knitted fabrics, ribbed fabrics, and double ribbed fabrics. Due to different organizational structures, the reflection is not obvious. First-class physical inspection is the basic condition, mainly for weaving services. Not only must the rough fabric meet the requirements, but the physical quality of the bare gray fabric after dyeing and finishing is no problem. Both unit strength and twist coefficient can meet the requirements. (1) The twist coefficient should not exceed 340 (2) The yarn count should be uniform (3) There should be as few foreign fibers as possible (4) The number of neps and impurities should be small, there should be no white spots with low coloring rate, and the dyeing uniformity should be good , it is best to reach level 4~5. (5) Less hairiness can reduce flying flowers during weaving and improve the surface finish of the finished fabric.
During 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:
1. The yarn should have a certain strength and extensibility
The strength of the yarn is the key to knitting. Important quality indicators of 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.
2. 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.
3. The thread 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 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 is required to be smooth, compact, with a 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 bias of the weft twist of the weft yarn 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.
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