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 Observation and comparison of the physical quality of the disassembled fabric determined it to be a cotton ball defective fabric. Once such defective fabrics appear, they are large-scale yarn defects that will cause serious losses to the enterprise. They are generally distributed in the carding process and the spinning process. Now. The process and control measures for producing small slub defects are analyzed as follows.
Pre-spinning and carding process
01 Causes and control measures of small slub defects
The characteristic of cotton ball defects on the cloth surface in the carding process is that the slub defects are very small, and the cloth The surface distribution is long segments of “Gypsophila”. After dismantling and analyzing, the fibers at the bamboo joints are twisted into cotton balls and attached to the surface of the yarn, which are easy to remove. The main reason for the small bamboo defects is: the cotton rolls in the carding process The feed is wet flower, and the fed tow fibers and grease are easy to stick 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 declining, etc. Sometimes the oil content of the polyester fiber is too low or the production If the relative humidity in the workshop is too high, it will also cause the carding machine to wind around the cylinder, resulting in poor fiber transfer and the formation of small slub defects.
Control measures: Strictly control the quality of raw materials, first use first , wet bales are not allowed on the machine; the roving ends are processed before being mixed with raw cotton; the relative humidity cannot be greater than 60%.
02 Causes and control measures of large cotton ball-shaped slub defects
The cotton ball defective cloth in the carding process has a large cotton ball shape on the cloth surface, and the slub defects are larger. are scattered over a wide range of the cloth surface. Most of the bamboo fibers are in a kink shape. These problems mainly occur in the front part of the carding process and are caused by operational factors; when some bamboo fibers are dismantled and analyzed, the fibers Short and without kinks, it mainly occurs in the large drain bottom part, which is caused by blockage of the drain bottom and hanging flowers.
Control measures: peel off the cotton apron and scrub regularly to eliminate hanging flowers. ; The front upper, front lower iron plate, rear upper and rear lower iron plate of the carding machine should be cleaned and polished regularly; all channel parts and doffer covers are found to be greased and not smooth, and should be cleaned regularly; the wall panels should be wiped clean and found to be If the cotton net has broken edges, it must be dealt with in time. The cotton ball defects in the carding process include small slub defects such as “gypsophila” or “neps” on the cloth surface. They are easy to peel off but cannot be moved.
Combing, drawing and roving processes
01 Combing process
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The combing process channel and the cylinder top combing brush are not smooth, and the coiling disc channel has burrs and burrs, resulting in rag silk. When the bamboo sections on the cloth are removed and analyzed, the fiber Short and without kinks, the color is yellowish.
Control measures: Check carefully during each shift handover, and provide timely feedback if any problems are found.
02 Drawing process
The scraper or fleece board of the pressing roller of the drawing frame is brought in, and the cloth surface also becomes Bamboo-shaped, but these bamboo joints are densely distributed. The bamboo joints are large and heavy. When the bamboo joints are decomposed, most of them are short velvet and velvet. The color is yellower and darker, which is easy to distinguish during analysis.
Control measures: Regularly check the condition of the pile board of the draw frame to prevent the accumulation of pile board; do the cleaning work lightly, frequently and at any time.
03 Roving process
The velvet pattern of the top roller is attached to the front of the roving, and the upper and lower aprons of the roving do not rotate. It is messy. There are too many fibers and pile fibers that are easy to attach to the yarn strips. When disassembling the fabric for analysis, the cloth surface is in the shape of a bamboo. After decomposition, there is a kink phenomenon, and there are random fibers. After spinning into fine yarn, small bamboo defects are attached to the yarn and can go back and forth. It moves, but the yarn with adhered fibers is hairy, not smooth, easy to break when pulled lightly, and is easy to distinguish from other processes.
Control measures: Check the upper, lower apron and pile of the roving at any time Whether the roller is running normally, and if any problems are found, deal with them promptly.
Post-spinning process
01 Spinning process
In the spinning process, small slubs form stripless dry-shaped white slubs on the cloth surface, that is, cotton neps (white stars) defective cloth, which also appears as “full” “Star” distribution. Due to the poor heat dissipation of the wire ring in the spinning process, it is easy to wedge outward and increase flying rings; the model is not matching, the replacement cycle of the wire ring is too long, and the winding tension is too high.
The cotton ball defects in the carding process and the cotton nep (white star) defects in the spinning process are often easily confused on the cloth surface. We can only analyze the cotton ball defects in the spinning process by disassembling the cloth and picking yarn. Small slubs Defects can move left and right on the yarn, the yarn is continuous, the yarn is smooth, and the twist is normal, but small slub defects cannot be removed.
According to the yarn picking analysis method and the spinning machine To distinguish them, the “Gypsophila” cotton ball defect 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 into details by the inner leg of the wire ring like a blade. The place where the yarn is scraped. Details are produced. The unscraped gauze is covered by the excess neps of the scraped gauze, resulting in thick spots and neps. Since the linear speed of the traveler is about 40m/s, the thick spots and neps on the cloth surface are The knots and details are distributed in short segments of “sky stars”.
Control measures: Selection of number of travellers, replacement cycle and weight control principles to maintain a normal air ring.
02 Winding and self-winding process
Trough speed Too fast, every centimeter of yarn traveling in the curved channel of the grooved drum will stick to the passage with grease and cotton wax, and then be wound around the drum.The S groove of the groove barrel must be checked frequently for smoothness, otherwise the “white stars” and “neps” will multiply after this process, and these “neps” cannot be removed or moved. The yarn is easy to break after light touch. This type of A large number of yarn defects can easily lead to uneven dyeing.
Control measures: winding and regular cleaning of the drum in the self-winding process.
Conclusion
In summary, to control small bamboo knot defects, the following aspects should be paid attention to: Raw cotton entering the factory Quality control must be carried out in each final process, and wet bags are strictly prohibited from entering the workshop; in key processes, the workshop temperature and relative humidity must meet production needs; all channels in the front and rear spinning processes should be cleaned regularly and inspected by designated personnel, and they must be kept smooth and free of lint; Stabilize the physical quality of cloth and knitted fabrics to reduce small slub defects and meet user needs.
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