Yarn hairiness refers to the fiber ends or loops that protrude from the main body of the yarn
my country Japan, the United Kingdom, Germany, the United States and other countries all use hairiness index to characterize the amount of hairiness. The definition of hairiness index is: on a certain side of the plane view of a single-sided yarn of unit yarn length, exceeding a certain projection length (vertical distance ), the unit is root/10m (the value of this indicator is affected by factors such as test length and projection length).
Have an impact
Hairiness causes the plush appearance of the yarn , reducing the glossiness of the yarn appearance. Excessive yarn hairiness will affect normal sizing and cause unclear openings and increased end breaks during the weaving process. The amount and distribution of yarn hairiness have a significant impact on the quality of the cloth and the dyeing and printing quality of the fabric. It will also cause pilling problems during fabric consumption. In particular, hairiness of more than 3 mm will seriously affect the subsequent production and affect the appearance, feel and performance of the yarn and its final product. Therefore, yarn hairiness index has become an important current quality assessment index.
Let’s briefly analyze the main factors affecting yarn hairiness:
01 The influence of raw materials on hairiness
The fiber length, fineness, maturity, short staple rate, impurities carried by the fiber, etc. of raw cotton play a role in the formation process of the yarn. , will have a direct impact on the generation of hairiness.
The greater the torsional stiffness and bending stiffness of the fiber, the more hairiness the yarn will have;
The torsional stiffness and bending stiffness of the fiber will be The greater the bending stiffness, the more hairiness the yarn will have;
The finer the fiber, the greater the number of fibers in the yarn cross section, and the greater the possibility that the fiber head end will be exposed, then The more likely it is to cause hairiness in the yarn;
The impurities carried by the fiber itself are prone to defects during the spinning process, affecting the normal operation and straightening of the whiskers, causing the The chance of fibers exposing the yarn body increases and hairiness occurs;
The fiber has good maturity, long length and good uniformity, and the fewer the number of fibers per unit length, the lower the yarn hairiness will be. The less.
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.
02 The influence of various pre-spinning processes on yarn hairiness
Keep all parts of the blowing and carding unit in good condition and set parameters reasonably. Reduce scratches and damage to the fibers to prevent more fibers from being broken during the high-power drafting process of the spun yarn, which will worsen the wear resistance of the yarn and increase hairiness. Enhance carding efficiency while minimizing the chance of short lint, straightening fibers and reducing the chance of hairiness.
Generally speaking, carded yarn has 30% to 40% more hairiness than combed yarn. Combing eliminates a large amount of short fibers in the cotton sliver, improves the straightness and parallelism of the fibers, and reduces the hairiness of the yarn. During the combing preparation process, attention should be paid to reducing the phenomenon of curling, combing should appropriately increase waste, keep the top comb, cylinder and brush in good working condition, and the entire cotton transport channel should be smooth and free of burrs.
During the drawing process, attention should be paid to draft distribution to improve fiber straightness and reduce the probability of hairiness. The bell mouth should not be hung, and the pressure rod should be checked regularly to ensure good condition.
The roving process should appropriately increase the roving twist coefficient to reduce yarn hairiness. At the same time, 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 process of pre-spinning 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.
03 Effect of post-spinning process on yarn hairiness
Spinning yarn It is a key process of spinning, and the quality of its spinning equipment has a greater impact on the hairiness of the yarn. For example: the diameter of the steel ring is inaccurate, the roundness and flatness are poor, or there are corrugations, burrs, unevenness and roughness, the ring plate is uneven or deformed due to movement, and the up and down movement is not vertical; the wire ring and the steel ring have poor coordination and embeddedness. Flowers; grooves in the yarn guide hook, friction on the yarn strips; misalignment of the spindle tip center, etc. will all lead to an increase in yarn hairiness. Spinning spindle speed, twisting area process conditions and equipment status, draft distribution, and twist coefficient will all affect yarn hairiness.
The weight of the traveler directly affects the hairiness. If 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 The tops of the bobbin collide and rub together to 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.
The winding process is the process where hairiness increases the most. The reason is mainly caused by the friction of the winding machine parts on the yarn. As the winding speed increases, the hairiness tends to increase, so the winding speed must be selected reasonably. During the winding process, all components in the winding channel must be kept intact and smooth to avoid friction and static electricity generated by the cotton yarn during movement, resulting in an increase in cotton yarn hairiness.
04 The influence of temperature, humidity and other factors
Theoretically Generally speaking, 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. Only long-term monitoring can see its impact on hairiness.Feather influence trends.
When the humidity is high, the fiber volume will expand, the air permeability will be poor, the strength of the single fiber will increase, the strength and friction resistance of the yarn will increase under the same conditions, and the hairiness will tend to decrease. Therefore, in the spinning and doffing processes, appropriately increasing the humidity of the processing environment is beneficial to reducing hairiness.
The mutual friction of the yarns themselves will also produce hairiness, and the friction of the bobbin yarn falling from the spinning machine or the package yarn that has been wound up will also occur during the unwinding, transportation and storage processes. Produce hairiness. Therefore, during the production process, care should be taken to handle it with care to minimize the chance of hairiness. </p
