Linear density and length of fibers and yarns

Linear density and length of fibers and yarns

Linear density and length of fiber The linear density of fiber refers to the thickness of the fiber. Fiber length refers to the length of the fiber.
Textile fibers must have a certain linear density and length so that the fibers can cohere with each other and be spun into yarn relying on the friction between the fibers. Therefore, textile fibers have a certain linear density and length, which is one of the necessary conditions for textile processing and making the product valuable.
The linear density of textile fibers is closely related to textile processing and the properties of the yarns and fabrics made. Generally speaking, lower fiber linear density and better uniformity are beneficial to textile processing and product quality. Among the effects of fiber linear density on the wearing properties of fabrics, fabrics made of finer fibers are softer and have a softer luster. Finer fibers can be used to produce lighter and thinner fabrics, and can also produce good breathability and silk-like effects. Good clothing fabrics. However, fabrics made of fine fibers are prone to fluffing and pilling, while fabrics made of coarse fibers can be made into stiff, rough and thick fabrics.
Similarly, the length of textile fibers is also closely related to textile and product quality. Longer fiber length, good length uniformity and less short fiber content are beneficial to textile processing and product quality. Under the same conditions, if the fiber is longer, the yarn will have high strength, uniform evenness, and the surface of the yarn will be smooth. The fabric will have good fastness, smooth appearance, and will not be prone to fluffing or pilling. In addition, under the premise of ensuring a certain yarn quality, the longer the fiber, the finer the yarn that can be spun, which can be used to make thinner fabrics. For short lengths, length is more important than linear density. For example, in the grade and pricing of cotton, length is an important indicator.
In textile fibers, the linear density and length of natural fibers are not uniform, and sometimes the differences are large. They vary with fiber varieties, growth conditions, etc. Chemical fibers are artificially manufactured, and the linear density and length of the fibers can be artificially controlled and determined within a certain range according to the requirements of fiber processing and use.
Bulk yarn Bulk yarn is first blended into yarn from two fibers with different shrinkage rates, and then the yarn is placed in steam or hot air or boiling water for treatment. At this time, the fibers with higher shrinkage rates produce larger The shrinkage is located in the center of the yarn, and the mixed low-shrinkage fibers are squeezed on the surface of the yarn to form a loop due to the small shrinkage, thereby obtaining a fluffy, plump, and elastic bulked yarn.
Core-spun yarn Core-spun yarn is generally made of a synthetic fiber filament with good strength and elasticity as the core filament, and is wrapped with cotton, wool, viscose fiber and other short fibers and twisted together. Core-spun yarn combines the excellent properties of filament core yarn and outer short fiber. The more common core-spun yarn is polyester-cotton core-spun yarn, which uses polyester filament as the core yarn and is wrapped with cotton fiber. There is also spandex core-spun yarn, which is a yarn made of spandex filament as the core yarn and wrapped with other fibers. Knitted fabrics or jeans made from this kind of core-spun yarn can stretch freely and fit comfortably when worn.
Linear density of fibers and yarns
Linear density is one of the most important physical and geometric characteristics of fibers. It not only affects textile processing and product quality, but is also closely related to the wearing properties of the fabric. Similarly, linear density is also an important indicator of yarn. The linear density of yarn affects the physical and mechanical properties, feel, style, etc. of textiles. It is also one of the important basis for fabric design.
The linear density of fibers and yarns has many expressions, and is generally expressed by indirect indicators proportional to the cross-sectional area of ​​the yarn. Commonly used indicators include Tex (number), metric count, imperial count, denier, etc. Generally speaking, the linear density indicators of fibers and yarns are mainly divided into two categories: fixed length and fixed weight.
Customized length refers to the weight of a certain length of fiber or yarn. The larger the value, the thicker the fiber or yarn. Currently commonly used are tex, decitex (dtex), millitex (mtex), denier (D), etc. my country’s legal unit of measurement is the special number system.
Tekes, referred to as “Tekes”, refers to the weight in grams of a 1,000-meter-long fiber or yarn at a publicly determined moisture regain. Tekes is commonly known as number for cotton yarn.
In addition, the diameter can also be used to express the linear density of the yarn. The diameter of the yarn is an important basis for fabric design and manufacturing process parameters. It can be measured under a microscope, but in actual production, the diameter of the yarn is converted by the special number or count of the yarn and the density of the yarn. And get.
In the expression of linear density of strands, the special number system is expressed by multiplying the special number of single yarns that make up the strand by the number of plies, such as 14×2. When the special numbers of the single yarns in the strands are different, it is expressed by adding the special numbers of the single yarns, such as 16+18. The count system is expressed by dividing the count of the single yarns that make up the strand by the number of strands, such as 50/2. If the counts of the single yarns that make up the strands are different, the counts of the single yarns should be juxtaposed and divided with a diagonal line, such as 24/48.
The multifilament linear density of chemical fiber is expressed by the number of single filaments that make up the multifilament and the total tex number. For example: 16.5 tex/30 f, which means the multifilament bus density is 16.5 tex and the number of single filaments is 30. The multifilament linear density of chemical fiber or silk is the sum of the linear densities of the single filaments that make up the multifilament.

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