Textile fiber generally refers to the diameter of a few microns or dozens of microns, the length of many times larger than the diameter, can be used to process the object of textiles, thin and long characteristics. Textile fibers must have a certain fineness and length so that they can be held together and spun into yarn depending on the friction between fibers. It is also one of the necessary conditions for textile processing and making products of use value.

Length is one of the main quality indexes of fiber material and an important factor to determine the spinning value of fiber material.

    The relationship between fiber length and yarn qualityFiber length is closely related to yarn quality. Mainly in the following aspects:

    1. fiber length and yarn strength in the yarn, if the fiber length is longer, the contact length between the fiber and fiber is longer, when the yarn is affected by external force, the fiber is not easy to slip, then the number of fibers slipping in the yarn due to tension is less, so the yarn strength is higher. The variation of fiber length has different effects on the strength of yarn. When the fiber length of the yarn is short, the length has a greater influence on the strength of the yarn. Among the commonly used textile fibers, the length of cotton fiber is relatively short, so its length has a greater impact on the yarn strength. Fiber length uniformity also affects yarn strength. The yarn strength of raw cotton will decrease significantly when the staple ratio is higher than 15%.

      2. Fiber Length and yarn density There is a limit value for the yarn density of fibers of all lengths. On the premise of ensuring the strength of the yarn, the longer the fiber length, the smaller the limit linear density of the spun yarn, that is, the thinner the spun yarn. The shorter the fiber length, the greater the limit linear density of the spun yarn, that is, the thicker the spun yarn. For example, the length of fine wool cotton under 25mm, generally can only spin more than 30tex medium, coarse special yarn; The limit linear density of fine cotton yarn with a length of about 29mm is 10tex. If you want to spin fine yarn with a length of less than 10tex, you must use long staple cotton. The longest fiber of long staple cotton can be spun to 3tex yarn.

      3.fiber length and yarn evenness the longer the fiber length, the higher the length uniformity, the better the yarn. When the fiber length is very short and the length uniformity is very poor, the yarn quality decreases.

     4. fiber length and yarn hairiness fiber is longer, the fiber head on the yarn is less exposed, yarn hairiness is less, the surface is smooth, on the contrary, yarn surface hairiness is more. Fiber fineness reflects the degree of fiber thickness. Like length, fiber fineness also has heterogeneity.

      Fiber fineness and yarn strength

Other conditions remain the same, the finer the fiber, the higher the strength of the yarn, the finer the fineness of the spinning yarn. This is because the fiber is fine, the number of fiber roots contained in the yarn cross section is more, the contact area between fibers is large, the chance of slippage between fibers is less, and the yarn strength is high. Cotton fiber due to thin wall and poor maturity of the fiber is relatively fine (single fiber strength is very low), then the yarn strength decreases.

        Fineness of fiber and evenness of finished yarn

Generally, the finer the fiber, the more uniform the number of fiber roots in the yarn section, the better the yarn evenness. Especially in spinning the thin yarn with fewer fiber roots, if the use of finer fiber, it is particularly significant to improve the yarn strength and yarn dryness. Fiber length is also closely related to the spinning process. From the structure and size of the spinning equipment to the technological parameters of each process, it must be matched with the fiber length used. For example, when the length of raw cotton is different, the beater form of the cleaning machine and the length of the feeding board of the card should be changed. Roller spacer in cotton spinning machine can be adjusted, when fiber length is long, roller spacer increases, fiber length is short, roller spacer decreases. The twist coefficient of spun yarn should also vary with the length of the fiber. In order to make the spun yarn have a certain strength, when spinning with short fiber, the spun yarn twist coefficient should be larger. When spinning with long fiber, the twist coefficient of spun yarn is generally small. Low twist coefficient can increase the yield of spinning frame.

Because of this, the fiber length is different, its corresponding spinning process should adopt different process parameters.