1、 Hairiness factors
1.1 raw material performance
Such as fiber length, uniformity, maturity, torsional strength, bending resistance, short fiber rate, etc.
1.2 process conditions during spinning
The degree of carding looseness, the degree of blow to the fiber, the degree of short fiber increase, the degree of fiber separation, the degree of parallelism, etc.
1.3 mechanical condition
(1) The smoothness of yarn channel, the contact area between yarn and channel, the tension of yarn passing through channel, etc.
(2) The size of the spinning triangle area has a great impact on the hairiness. According to relevant data, the spinning hairiness produced by the spinning triangle area accounts for 80-85% of the whole yarn hairiness. Almost 80% of the flying flowers in the spinning workshop are produced by the spinning triangle area.
(3) The ring and coil are in poor condition, with short service life and inconsistent matching, resulting in yarn tension difference and hairiness increase.
(4) Spinning components, roller, apron, roller, yarn guide hook, upper and lower pins, and buncher all have an impact on hairiness.
2、 Harm of yarn hairiness
(1) Hairiness will affect the gloss of the yarn appearance, and also reduce the strength and wear resistance of the yarn. Hairiness above 3mm will seriously affect the production of the subsequent process and the hand feel, appearance and service performance of the product. Excessive hairiness will also affect the normal sizing.
(2) Uneven hairiness distribution on the yarn or new neps formed by hairiness in the weaving process will affect the appearance quality of dyed fabrics, and some will form rung defects; The yarn hairiness difference produced in the spinning process is easy to cause the dyeing difference of grey cloth, forming the rung defect and dyeing defect.
(3) When producing high-density fabrics on air-jet looms, the hairiness will cause the adjacent warp yarns to intertwine with each other, resulting in unclear openings. The hairiness of more than 3mm on the warp will also make the warp guide fail. Taking 30 British count yarn as an example, if the hairiness length on the yarn is 3mm, the yarn diameter will increase by 18 times, and the opening height of the air-jet loom will be 3.5mm. The existence of hairiness will reduce the effective height of the loom opening, make the warp opening unclear, block the weft flight, and cause a stop. According to statistics, 75% of the stoppages of air-jet looms are related to yarn hairiness.
(4) The hairiness on the yarn is easy to fall off and form flying flowers due to friction in the downstream processes, polluting the environment and endangering human health; It is also easy to produce new defects, which will reduce the quality of yarn and fabric.
3、 Methods and measures for controlling hairiness
3.1 raw material properties
3.1.1 fiber length
Length one: it will reduce the number of fibers per unit length of yarn, thus reducing hairiness; Second: the fiber is easy to be twisted, making the yarn structure compact and less hairiness. On the contrary, hairiness will increase. See Table 1 for comparison test.
3.1.2 fiber uniformity and maturity
If the fiber maturity is too large, the fiber rigidity increases and the holding force decreases, resulting in the increase of yarn hairiness; When the maturity is too small, the fiber strength is small and easy to break, resulting in the increase of short fiber and yarn hairiness. There are many short fibers, the corresponding fiber uniformity is poor, and the number of fibers per unit section increases, resulting in the increase of yarn hairiness; Good fiber regularity leads to less yarn hairiness. See Table 2 for comparison test.
Note: the yarn type is cfcj9.72te x
3.1.3 single fiber strength and breaking strength
When the single fiber strength is large and the breaking strength is increased, the cotton fiber is not easy to break during processing, and the yarn hairiness is small. The cotton fiber strength is not only related to the fiber thickness, but also related to the fiber variety and maturity. For example, the long staple cotton has small thread density, long fiber length, good maturity, and large single fiber strength, so the yarn hairiness is small. See table for comparison test.
Note: the spinning type is cfcj9.72tex
3.1.4 short fiber rate
The higher the fiber shortness rate, the more unfavorable it is for the drafting mechanism to effectively control the fiber movement and improve the fiber straightening parallelism in the whisker, resulting in excessive shift deviation in the drafting process, resulting in excessive concentration of fiber speed change points, resulting in easy slippage and hairiness between fibers. See Table 4 for comparison test.
Note: the spinning type is cfcj9.72tex
3.1.4 linear density
The smaller the linear density, the more fibers in the yarn section, the greater the holding force and friction between fibers, and the fibers are not easy to slip under the action of external forces. Short fibers are easy to be controlled by the drafting mechanism, so that the fiber speed change points are concentrated, the number of floating fibers is reduced, and the yarn structure is compact, the surface is bright and clean, and the yarn hairiness is less. See Table 5 for comparison test.
3.1.5 cotton blending method
Control the proportion of back flower. The fiber is seriously damaged after repeated blows, which is easy to increase hairiness. The amount of back flower should be controlled within 5%. Before packing, loosen the package in advance to make the fiber hygroscopic and balanced, which is conducive to the control of hairiness. Selection of raw materials: according to the above comparison results, the fineness, length and regularity of the fiber should be well controlled to create good conditions for reducing hairiness. When spinning chemical fiber, attention should be paid to the content of oiling agent. If the content is small, it is easy to generate static electricity and cause the yarn to hair; High content is easy to contaminate the roller and cause the top of the channel, which will increase the hairiness. At the same time, it will also cause poor carding and drafting, and reduce the quality of semi-finished products.
3.2 influence of process and special equipment on Yarn Hairiness
3.2.1 cotton cleaning process
The key point is to reduce fiber damage, keep the air flow unobstructed, and avoid traffic jam and choking. Avoid large amounts of twine and neps. The low impurity raw materials adopt the process principle of "reducing the speed of the thugs and enlarging the distance between holding strike points". The cotton grabbing machine shall be "light, fine, small, full and even", which is conducive to loosening, mixing, efficient impurity removal and fiber damage reduction. The air flow at the inlet and outlet of the cotton opener shall be well controlled, and the dust stick shall be kept smooth without burr, rust and cotton wax, so as to prevent the dust stick from being burnt and excessive recycled lint impurities. The process principle of "thin feeding, fast feeding, soft opening and strong elimination" shall be adopted for the holding and striking equipment to reduce the growth of neps and short fibers. For multi warehouse equipment, the pressure for changing warehouse shall be optimized. Under the condition of ensuring smooth operation and normal supply, it is better to control the pressure slightly. It is also necessary to ensure the operation efficiency of each single machine, especially the cotton grabbing machine and multi bin cotton mixer. On the premise of ensuring normal supply, the higher the better, so as to meet the process requirements of uniform and continuous feeding.
3.2.2 carding process
The technological idea of carding process is to reduce fiber damage, eliminate short fibers, and improve fiber straightness and parallelism. Follow the process principle of "appropriate carding and transfer, consideration of impurity and short pile, reasonable air flow parameters, and reasonable clothing matching". The sliver weight shall be reasonably controlled, the weight shall be fixed, the feeding cotton layer shall be thick, and the load of the cylinder card cloth shall be large. Light weight, high carding degree and large fiber damage. In addition, we should grasp the main speed and spacing.
α、 The speed shall be reasonably selected according to the carding degree requirements. For the speed of cylinder and take-up roller, high speed and strong carding effect will cause large fiber damage, increased short fiber and more hairiness. The determination of tin to thorn ratio is very important to control hairiness. With the increase of the speed of the movable cover plate, the carding degree and the fiber transfer rate of the fibers are correspondingly increased, which is beneficial to eliminate short fibers and reduce impurities.
b. The spacing shall follow the process principle of progressive carding, properly handle the relationship between holding carding and free carding, give full play to the role of each spacing, balance the relationship between all spacing, and ensure to reduce the production of short fibers and increase the elimination of short fibers under normal carding conditions.
c. Reasonably select the needle cloth, and adopt the new needle cloth which is short, shallow, small, sharp, thin and dense. Their characteristics are that the needle tip is sharp, the surface is smooth and smooth, and the consistency is good, which can not only ensure the carding and transfer of the fiber, but also relatively reduce the damage of the fiber.
d. Control the equipment status of the carding machine, avoid ignoring the equipment status, unilaterally pursue high-density and strong carding, and increase fiber damage. The mechanical state and process of the equipment shall meet the basic requirements for installation, "flat, straight, stable, accurate and smooth".
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