1. Basic overview
Yarn hairiness is caused by the fibers exposing the surface of the yarn body during the yarn forming process. Cotton yarn is formed by twisting and condensing short fibers one by one. It is inevitable that hairiness protrudes from the yarn body. According to the different shapes of fibers extending out of the yarn matrix, hairiness is divided into three types: end hairiness, loop hairiness and floating hairiness; according to the yarn direction, it is divided into: head hairiness, tail hairiness, two-way hairiness, loop hairiness and random hairiness. wait. Generally speaking, hairiness with a length of 0.5~1mm accounts for about 60% of the total number, hairiness with a length of 1~3mm accounts for about 35% of the total number, and hairiness with a length of 3mm or more accounts for about 5% of the total number of hairiness.
Hairiness is an important quality indicator that affects the appearance and style of yarn. The state of yarn hairiness directly affects weaving efficiency, fabric style and dyeing effect. In particular, hairiness above 3mm will seriously affect the subsequent production, affecting the appearance, feel and performance of the yarn and its final product.
For example, the yarns are easily tangled, causing the yarns to fail to pass through the stopper, heddle eyelets and reed teeth smoothly during weaving, resulting in unclear openings or increased ends breakage. When used on shuttleless looms, because the looms mostly operate with small sheds, large tension, and high speeds, if the yarn hairiness problem is serious, it will cause warp yarn breakage and reduce the weaving efficiency.
With the rapid changes in textile products and people’s diverse consumer needs, newer requirements have been put forward for the hairiness problem of yarns in recent years.
Due to the irregular shape of hairiness of ring yarn, the distribution on the yarn surface is random. Even if the lengths of large, medium and small yarn sections of the same tube yarn reflect various hairiness values, the hairiness values of various lengths are often very different. Therefore, how to analyze and evaluate the hairiness status of ring-spun yarns in our factory, and establish and strengthen the quality control and management of yarn hairiness, we must proceed from the actual situation of the enterprise, make full use of advanced yarn hairiness detection methods, and formulate quality standards related to hairiness. Prevent the occurrence of hairiness and meet user requirements.
2. Several phenomena of poor hairiness:
Yarn hairiness problems include the following phenomena:
1. The overall value of hairiness is high and the cloth surface is not clear, which seriously affects the dyeing effect;
2. The CV value of hairiness is high and the cloth surface is not smooth, causing dyeing differences;
3. A few yarns have dense hairiness, which results in the formation of cotton balls and neps in the weaving channel, affecting end breaks and fabric surface quality.
3. Factors affecting yarn hairiness
Hairiness is mostly produced during the drafting and twisting and winding processes of the spinning frame. The amount of hairiness after winding is 2-4.5 times that of the original yarn, seriously affecting the processing quality and production efficiency of subsequent processes. Many textile companies We have racked our brains and tried our best on how to solve the problem of yarn hairiness, but the results are not ideal. Let’s briefly analyze the factors that affect yarn hairiness:
1. The influence of raw materials on hairiness. The fiber length, fineness, maturity, short staple rate, and impurities carried by the fiber of raw cotton will have a direct impact on the generation of hairiness during the yarn formation process.
The fiber length is long, the uniformity is good, the cohesion between fibers is large, and the probability of hairiness formation is small; when the fiber length is short, the fiber cannot be covered normally during the spinning process, leaving one end of the fiber exposed. The outer end of the “spiral” of the yarn body has more opportunities to form hairiness; the impurities carried by the fiber itself are prone to defects during the spinning process, affecting the normal operation and straightening of the whiskers, increasing the chance of the fiber being exposed to the yarn body. Hairiness is produced; the higher the lint rate of raw cotton, the greater the probability of hairiness formation due to more floating fibers during the drafting process; the higher the maturity of raw cotton, the stronger the cotton fibers, the fibers are relatively uniform in thickness and longer in length. The number of fibers per unit length of the yarn is reduced, and the fiber ends are reduced. Moreover, long thin fibers are easily affected by twisting torque and friction between fibers, which shortens the length of the fiber ends that may protrude from the yarn body. Therefore, the yarn body is smooth and has less hairiness; when the micronaire values between the marks in the same batch of raw materials are greatly different and the consistency is poor, the controllability of the fiber decreases during operation and hairiness is likely to occur. Therefore, in the daily production process, the quality of cotton and the usage rate of returned flowers should be strictly controlled to improve the consistency and stability of raw materials.
2. The influence of each pre-spinning section on yarn hairiness
The joint cleaning line of steel cleaning will also have a certain impact on the hairiness of the yarn. It is required that the channel parts of each equipment are smooth and free of burrs, and there is no hanging phenomenon (hairiness is formed due to scratching). Beaters, dust sticks, and cotton conveying curtains There should be no burrs or burrs on the card to reduce scratches and damage to the fibers; the card clothings of the carding machine should be sharper to enhance carding efficiency and reduce the chance of short lint, and the cylinders, doffers and cover plates should be properly positioned The configuration of speed, gauge and draft further straightens the fibers and reduces the chance of hairiness formation. The blowing and carding process has a relatively strong impact on the fibers. During the high-power drafting process of the spun yarn, more fibers are broken, which makes the wear resistance of the yarn worse and the hairiness increased.
Combing section:
Generally speaking, carded yarn has 30% to 40% more hairiness than combed yarn. Through the combing process, a large number of short fibers in the cotton sliver are eliminated, and the straightness and parallelism of the fibers are improved, so the hairiness of the yarn will be reduced.
During the combing preparation process, attention should be paid to reducing the sticking phenomenon.It is necessary to increase the waste, keep the top comb, cylinder and brush in good working condition, and the entire cotton conveying channel should be smooth and free of burrs.
In the drawing section, attention should be paid to the draft distribution to promote the straightening of the hook fibers, thereby reducing the probability of hairiness formation. The bell mouth should not be hung, and the pressure rod should be checked regularly to ensure it is in good condition.
In the roving section, the hairiness of the finished yarn will decrease as the twist of the roving increases. The more hairiness of the roving, the hairiness of the fine yarn will also increase. All places where cotton slivers pass must be kept smooth and there should be no hanging flowers. .
The plastic sliver cans and slivers used in each section of the pre-spinning process are prone to static electricity due to friction with each other. The fibers repel and attract each other. Some short velvet cannot be covered normally and form hairiness. The plastic sliver cans must be smooth and burr-free.
The hairiness of the yarn is mainly produced in the spinning and troughing processes.
1. The influence of the spinning process on hairiness. Spinning is a key process in spinning, and the quality of its spinning equipment has a greater impact on the hairiness of the finished yarn.
The main manifestations are:
(1) The diameter of the ring is inaccurate, the roundness and flatness are poor, or there are ripples, burrs, unevenness and roughness. The ring plate is uneven or deformed due to movement, and the up and down movement is not vertical, which will cause fluctuations in the spinning tension. Increased friction effects lead to increased yarn hairiness;
(2) Poor coordination and intarsia between the traveler and the steel ring will cause a significant increase in yarn hairiness;
(3) The friction between the guide yarn hook and the yarn strip will increase the hairiness;
(4) The center of the spindle tip is not accurate, causing the spinning tension to fluctuate and increase the amount of yarn hairiness;
(5) The spinning spindle speed is also an important factor affecting hairiness. The number of yarn hairiness increases in proportion to the spinning spindle speed;
(6) The process conditions and equipment status of the twisting part of the spinning machine are poor. The yarn is scratched, which will damage the yarn structure and increase the hairiness. During the twisting process, foreign flying flowers and short velvet adhere to the yarn body and partially twist it. Hairiness will also form in the yarn.
(7) The draft of the spinning frame has a particularly great impact on hairiness. The greater the draft multiple in the rear area, the hairier will increase accordingly. In addition, as the twist coefficient of the spun yarn increases, the hairiness will decrease;
(8) The weight of the traveler directly affects the hairiness. During the twisting process, the traveler makes rapid jumping motion (not frictional motion) along the ring track. When the ring plate is in the small yarn position, the balloon tension is too tight. , this is the best time for hairiness to occur. The traveler is too heavy, the spinning tension is high, and the balloon is small, which increases the friction between the traveler and the yarn, causing the yarn to collide with the top of the bobbin and produce hairiness. At the same time, the yarn is also easily scratched and neps are formed. If the traveler is too light, the spinning tension will be small, and the balloon will be too large, causing the yarn to collide with the spacer plate and produce hairiness.
2. The influence of winding process on hairiness
The winding process is a key process for hairiness growth and has a great impact on hairiness. The main manifestations are:
(1) Once all the components in the winding channel have burrs, grooves, or damage, and the surface where they contact the yarn is not smooth, the cotton yarn will experience greater friction during movement and generate static electricity, resulting in an increase in cotton yarn hairiness;
(2) When the pagoda tube, bobbin and grooved tube are not well matched, the package yarn will jump and slip during movement, which will lead to local increased friction of the package yarn, and the cotton yarn hairiness will increase significantly;
(3) Process parameters: The higher the vehicle speed, the greater the friction between the yarn and the groove drum, the greater the damage to the yarn, and the increase in hairiness; the greater the winding tension, the greater the friction between the yarn and various components of the winding channel As the force increases, the hairiness of the cotton yarn becomes longer and increases; the package volume also has a certain impact on the hairiness of the cotton yarn. If the package is too large, the weight of the package will be large, the friction between the package and the grooved tube will be large, the yarn will be damaged, and the cotton yarn will be damaged. The amount of hairiness will increase.
Temperature, humidity and other effects
Theoretically, humidity is one of the main causes of changes in hairiness. However, in actual production, due to the instability of various conditions, it is difficult to quantify its impact on hairiness. It can only be seen from long-term monitoring. Its influence on hairiness trends.
If the humidity is high, the fiber volume will expand, the air permeability will be poor, the single fiber strength will increase, the yarn can withstand increased strength and friction resistance under the same conditions, and the hairiness will tend to decrease. Therefore, during the spinning and doffing processes, the processing environment should be appropriately increased. Humidity is conducive to the reduction of hairiness. When the relative humidity in the spinning workshop is lower than 50%, the hairiness of the yarn will increase sharply.
Hairiness will also occur when the yarns themselves rub against each other, and when the bobbin yarn dropped from the spinning machine or the package yarn that has been wound up rubs against each other during unwinding, transportation, and storage, hairiness will also occur. Therefore, during the production process, care should be taken to handle it with care to minimize the chance of hairiness.
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