Small slub defects are common in the production process. To eliminate small slub defects, supervision must start from the front process of the fabric. Such defects all appear as small slubs when observed from the fabric surface. According to the evenness tester test data analysis and fabric After observing and comparing the physical quality of the disassembled cloth, it was determined to be cotton ball defective cloth. Once such defective cloth appears, it will be a large number of yarn defects, which will bring serious losses to the enterprise. They are generally distributed in the carding process and the spinning process. Now. The production process and control measures of small slub defects are analyzed as follows.
Pre-spinning and carding process
01 Causes of small slub defects And control measures
The characteristics of the cotton ball defective cloth in the carding process are that the slub defects are very small, and the cloth surface is distributed in long segments of “starry sky”. After dismantling and analyzing the fabric, it was found that the fibers at the slub knots were twisted into cotton balls and attached to the surface of the yarn sliver, which were easily removed. The main reason for the small slub defects was that the cotton rolls fed into the carding process were wet flowers, and the fed tow fibers ､Grease easily sticks to the card clothing, the distance between the cylinder and the doffer is incorrect or too small, the surface of the card clothing is uneven and the card clothing is degraded, etc. Sometimes the oil content of the polyester fiber is too low or the relative humidity in the production workshop is too high, which can also cause problems in the carding machine. Cylinder winding leads to poor fiber transfer and small slub defects. Control measures: Strictly control the quality of raw materials, first-in-first-out, wet bags are not allowed to be put on the machine; roving end processing Then mix it with raw cotton; the relative humidity cannot be greater than 60%.
02 Causes and control measures of large cotton ball-shaped slub defects
Some of the cotton ball defects in the carding process are in the shape of large cotton balls on the cloth surface, and the larger slub defects are scattered over a wider range of the cloth surface. Most of them are slub fibers. These problems mainly occur in the front part of the carding process and are caused by operational factors; when disassembling and analyzing some bamboo sections, the fibers are short and have no kinks, which mainly occur in the large drain bottom part, which is blocked by the drain bottom. Caused by hanging flowers.
Control measures: scrub the cotton peeling apron regularly to eliminate hanging flowers; carding machine has front upper and front lower iron plates, rear upper and rear lower iron plates. The board should be cleaned and polished regularly; all channel parts and the doffer cover are found to be greasy and not smooth, so they should be cleaned regularly; the wallboard should be wiped clean, and if the cotton net is found to have broken edges, it should be dealt with in time. Defects in the cotton ball during the carding process ” The small slub defects of “Gypsophila” or “Cotton Neps” are analyzed on the cloth surface using the method of removing cloth and picking yarn. The small slub defects of “Cotton Balls” are easy to peel off, but cannot be moved.
Combing, drawing and roving processes
01 Combing process
Combing process channel and cylinder The top combing brush and other parts are not smooth, and there are burrs hanging on the looping plate channel, resulting in rag silk. When the bamboo joints on the cloth are disassembled and analyzed, the fibers are short and unkinked, and the color is yellowish.
Control measures: Check carefully during the handover of each shift, and provide timely feedback if any problems are found.
02 Drawing process
The drawing frame is brought in by the scraper blade or velvet board flower of the pressing roller, and the cloth surface is also in the shape of bamboos, but such bamboos are densely distributed. The bamboos are large and heavy. When the bamboo joints are decomposed, most of them are short velvet and velvet board. The color is yellower and darker, which is easy to distinguish during analysis.
Control measures: Check the draw frame velvet regularly. Check the condition of the board to prevent the accumulation of velvet board; do the cleaning work lightly, frequently and at any time.
03 Roving process
The top rollers of the roving have velvet attached to them, and the upper and lower aprons of the roving do not rotate. There are too many random fibers and velvet, which easily attach to the yarn strips. When disassembling the fabric and analyzing it, the cloth surface appears as a slub. After decomposition, there are kinks and random fibers. After being spun into fine yarn, the small slub defects are attached to the yarn and can move back and forth, but the yarn with adhered fibers is hairy, not smooth, and easy to break when pulled lightly, making it easy to distinguish it from other processes.
Control measures: Check whether the upper, lower apron and pile rollers of the roving are operating normally at any time, and deal with any problems in a timely manner.
Post-spinning process
01 Spinning process
In the spinning process, small slubs form stripless white slubs on the cloth surface. , that is, the fabric with neps (white stars) defects is also distributed in a “starry sky”. Due to the poor heat dissipation of the wire rings in the spinning process, it is easy to be wedged outward, which increases the number of flying rings; the model does not match the model, and the replacement cycle of the wire rings is too long, resulting in winding The tension is too high.
The cotton ball defects in the carding process and the neps (white stars) defects in the spinning process are often easily confused on the cloth surface. The only way to remove the cloth is to pick it out. Yarn analysis shows that the cotton ball defective fabric belongs to the spinning process. Small slub defects can move left and right on the yarn sliver, the yarn is continuous, the sliver is smooth and clean, and the twist is normal, but the small slub defects cannot be removed.
According to the analysis method of dismantling and yarn picking and the concentration of spinning machines, the cotton ball defect in the “Gypsophila” in this example is caused by the poor heat dissipation of the wire ring in the spinning process, which causes the yarn to be scraped by the wire ring like a blade. The inner ring foot of the scraper is scraped into details. Details are produced where the yarn strips are scraped. The unscraped yarn strips are covered by the excess neps of the scraped yarn strips, resulting in thick spots and neps. Since the linear speed of the traveler is 40m /s, so the thick spots, neps, and details on the cloth surface are distributed in short segments of “starry sky”.
Control measures: Selection of the number of travellers. The replacement cycle and the principle of controlling the severity are based on maintaining a normal air ring.
02 Winding and self-winding process
The speed of the trough drum is too fast. Every centimeter of yarn traveling in the curved channel of the trough drum sticks to the passage with grease and cotton wax, and is then wound around the yarn. S groove of the trough drum The smoothness must be checked frequently, otherwise after this process, the “white stars” and “neps” will multiply, and these “neps” cannot be removed or moved. The yarn is easy to break after light touch. This type of yarn has a large amount of defects, and�Resulting in uneven dyeing.
Control measures: winding and regular cleaning of the drum in the self-winding process.
Conclusion
To sum up, in order to control small bamboo defects, the following aspects should be paid attention to: quality control must be carried out in each process after raw cotton enters the factory, and wet packaging is strictly prohibited from entering the workshop; key processes The temperature and relative humidity of the middle workshop must meet production needs; all channels of the front and rear spinning processes should be cleaned regularly and inspected by designated personnel, and must be kept smooth and free of hanging flowers; the physical quality of cloth and knitted fabrics should be stabilized to reduce small slub defects and satisfy users Required.</p
