The new normal development of the textile industry, the market competition is extremely fierce, the textile industry product quality requirements are getting higher and higher. After manufacturing, dyeing and finishing, downstream customers often complain about textile mills for quality problems and defective products. The thorny problem that plagues spinning mills is the analysis and treatment of fabric rungs, which is a complex situation.

 

At present, there is no testing institution in China to make a conclusive judgment on the quality of the cross-piece cloth. It is relatively easy to analyze the crosspieces of woven fabrics, while it is difficult to analyze the causes of crosspieces and bar defects of circular woven fabrics and how to analyze and judge them. Exploring and mastering the causes of the formation of the relevant fabric crosspieces and their analysis methods will help the production management of each link in the industrial chain, and provide a reliable objective basis for reducing the occurrence of crosspiece defects and avoiding unexpected economic losses.

 

Characteristics of fabric rungs and their hazards
 

Bars with different color and luster appear on the surface of the natural gray fabric or after dyeing and finishing. The rungs of round woven fabrics are mostly characterized by regular bars. The abnormal cloth bar is composed of one or more yarns. There will be some differences between the yarn at the crosspiece and the yarn at the normal cloth surface in terms of color difference, thickness, composition, twist, hairiness, loop, density, stretch yarn tension, etc. The factors that form the crosspiece of circular woven fabrics are caused by yarn, circular machine manufacturing, and dyeing and finishing.

 

There are many situations such as the wrong manufacturer, the wrong variety, the fluctuation of raw materials, the uneven mixing of cotton, the use not according to the order of production time, the mixed batch use of yarn or spandex, the uneven yarn feeding tension of the round machine, etc. The occurrence of circular woven fabric rungs defective cloth, generally a large number, less a few cloth, more than a few dozen. If the downstream process is not used in time, the consequences will be more serious. The harm caused by the crosspiece defect is relatively large, plus the base material, auxiliary materials, processing fees and dyeing and finishing fees of the weaving factory, the cost of defective products is much higher than the value of the original yarn, and even doubled the value of the original yarn.

 

Round woven fabric rungs are inferior cloth, difficult to trim. Because there are many cycles between cloth veil roads, the spacing between rungs is only about 3cm ~ 5cm, which cannot be cut, and the color fading treatment will also incur a lot of expenses. To master the causes and analysis methods of the formation of fabric crosspiece, and to find the objective and real factors that form the inferior products of the crosspiece, so as to prevent and reduce the occurrence of crosspiece defects and reduce accidental economic losses.

 

1. Factors Causing Rings of Round Woven Fabrics by Spinning Mill

① The origin, batch, color, whiteness, performance, cotton maturity, micronaire value difference and other factors of spinning raw materials are affected by the quality difference of raw materials, which will cause fabric crosspiece.

The use of raw materials for the transition batch processing is improper, especially the quality of the batch of raw materials with the previous batch of large differences, the longer the transition time, the smaller the incremental amount of raw materials into the batch, resulting in the less the probability of fabric crosspiece, the more vice versa.

③The uneven mixing of raw materials of different origins, different batches and different specifications, and the uneven mixing of raw materials of different components of blended varieties will cause fabric crosspiece.

④ There are two ways of mixing raw materials: bag mixing and strip mixing. Strip mixing is more accurate than bag mixing and fiber mixing. However, it is important to control the weight unevenness of carding strips and add the process when necessary to control the accurate blending ratio.

⑤ When wrapping on the cotton table, pay attention to the uniform arrangement of the wrapping, cut the height and fill the wrapping, especially the cotton roll at the end of the wrapping head is easy to mix unevenly, so it should be unrolled for use. Roll back, strip back and flower back should be uniform in the longitudinal direction. Cotton catchers should catch less and more frequently, and keep the operation rate of cotton catcher above 92%.

⑥ When the method of mixing cotton with raw materials is implemented, under the condition that there is no multi-bin cotton blender, secondary rolling shall be implemented when necessary, and primary rolling shall be carried out on the cotton platform, middle and lower layers. It is necessary to classify and discharge evenly so that the mixing of different fibers will be more fully consistent. Or add a cotton blending process, pack the pre-mixed raw materials into a package, then go to the chartering machine and enter the flower cleaning process.

⑦ When implementing the mixed fiber mixing mode, the feeding positions of different fibers should be fixed and consistent, and the position structure of various fibers in the yarn should be kept the same.

⑧ When producing multi-component blended varieties with more than 3 kinds of fibers, a combination of bag blending and strip blending can be adopted. After some fibers are selected to be mixed into strips, they are mixed with another part of fiber strips to ensure uniform mixing of multi-component fibers.

⑨ Production of the same variety, arrange the same model of equipment production, to maintain process consistency, to avoid differences in cotton yarn quality due to differences in models, inconsistent processes. Different types of equipment to produce the same variety of cotton yarn, mixed on the same circular machine, due to the weight deviation of cotton yarn, twist, dry, hairiness, etc. have certain differences, the cloth surface will appear crosspiece, especially light and thin fabric cloth surface is more obvious.

⑩ When the weight deviation of cotton yarn is more than 3.5 and above, the difference of blending ratio is more than 2.5, and two or more similar yarns are used together, bleached cloth will have obvious rungs. When the twist difference is more than 4%, the fabric rungs will also appear on the bleached or dyed fabric surface.

All kinds of equipment should be clearly distinguished in the process of use. All kinds of finished products and semi-finished products should be stored in different categories. It is strictly prohibited to mix, mix and beat, and mix, so as to prevent the cloth crosspiece caused by quality accidents of wrong varieties.

 

2. Factors Causing Rings of Circular Woven Fabrics in Knitting Factory

① Not according to the order of cotton yarn production date, mixed batch, mixed factory use. The pretreatment management is chaotic, the singeing quality control is poor, and the batch and production date are not marked after singeing.

② Poor operation of the car blocker, wrong yarn arrangement, wrong yarn replacement, wrong yarn wearing after breaking, spandex elastic yarn without patching after breaking.

③ Poor equipment running state and poor equipment debugging state. The sinker, sedimentation triangle and knitting needle triangle are seriously worn, and the centricity of the needle cylinder is poor.

④ Inappropriate tension of bobbin yarn lead will result in regular fabric crosspiece, and poor state of circular machine yarn feeding plate and yarn feeder will result in fabric crosspiece with wide spacing.

⑤ During the use of spandex elastic yarn, there are wire leakage, broken wire, reverse wire and double wire. The spandex yarn bobbin of the same circular machine is inconsistent in size and large in difference, resulting in inconsistent tension of spandex yarn. The fabric rungs with regularity and wide spacing are closely related to the uneven tension of the circular machine spandex.

The circular machine production process, there is a yarn coil size is not consistent, the coil is large, there will be a large fabric density, otherwise the fabric density is small.

⑦ The yarn in the round woven fabric is horizontal patrol, and the longitudinal defects are mostly caused by knitting needles, which are generally not directly related to the yarn quality.

⑧ The installation position of the clutch is different, the yarn feeding speed is different, and the cross gear of the cloth surface is easy to appear.

 

3. Factors Caused by Dyeing and Finishing Factory to Cause Rings of Circular Fabric

① Poor condition of dyeing and finishing equipment, eccentric and bent pad dyeing stick, poor roundness, and poor printing machine set net will cause cloth crosspiece.

②The crosspiece caused by printing and dyeing parking is not paid attention to operation, the parking time is long, the roller stays on the cloth surface, the mark appears in the color liquid, and the crosspiece is more obvious after the cloth surface is dried.

③ Direct dyeing without pretreatment or improper pretreatment, dyeing time, temperature, pressure, dyeing material ratio is unreasonable, and the color of the cloth surface is uneven.

④ The fibers in the cotton yarn have hygroscopicity, the moisture regain is inconsistent, the cloth surface is locally wet and dry, and the coloring is inconsistent, resulting in dyed crosspiece of varying depth.

⑤ When the water evaporates and lacks water during scouring, the dyed cloth surface is partially exposed to the dye solution, and the coloring is uneven. There is no obvious regularity in the spacing between the rungs of this kind of cloth surface.

⑥ In the finishing process, improper handling of high temperature tenter, resulting in tenter tooth mark fabric crosspiece. The fabric crosspiece caused by dyeing and finishing factors generally disappears after fading.

⑦ When pre-baking after padding and dyeing solution, due to the inconsistent drying rate, the dye will have different degrees of swimming and the distribution of dye on the surface of the fabric will be inconsistent.

 

4. Fabric rung analysis method and operation steps

① Most of the rungs on the cloth surface do not appear on the white gray cloth, and horizontal stripes appear on the cloth surface after dyeing. Regular horizontal formation of a single yarn is generally caused by wrong yarn. Regular wider horizontal strips, with multiple yarns forming horizontal formation, are generally caused by fluctuations in the quality of raw materials, mixed batch use of yarns or inconsistent tension of spandex stretch yarn.

② When receiving the crosspiece fabric sample, first visually inspect the distribution state of the bars, and comprehensively analyze the cause of the fabric crosspiece by means of cloth removal, instrument test and chemical dissolution. To grasp the color difference characteristics, further analysis of mixed batch, twist, yarn branch, wrong yarn, uneven elasticity and other factors caused by the cloth cross.

③ Cut a piece of cloth of equal length from the bar cloth surface. After removing the cloth, measure the yarn length at the bar and the normal place under the state of natural elongation. If there is any difference in yarn length, it may be caused by the inconsistency of coil size or tension.

④ After unpacking, test the twist, yarn count, strand and hairiness of the yarn at the crosspiece with a spinning test instrument, and compare whether there is any difference between the yarn at the crosspiece and the yarn at the normal place.

⑤ According to FZ/T 01057.4-2007 standard, the "chemical dissolution method" is used to dissolve the spandex in the fabric for the rung fabric sample containing spandex elastic yarn, and then washed and dried. Judging from the cloth surface with only yarn fibers left, whether the characteristics of the rung are consistent with the characteristics of the original cloth surface. If the pure yarn fabric sample has no bar phenomenon, the rung caused by yarn factors can be eliminated.

⑥ Similarly, the yarn fibers in the fabric are dissolved by "chemical dissolution method", and then washed and dried. Judging from the cloth surface with only spandex silk left, whether the characteristics of the crosspiece are consistent with the characteristics of the original cloth surface. If the pure spandex silk cloth surface has the phenomenon of equivalent bars, it can be confirmed that the crosspiece is caused by the spandex tension problem in the knitting factory.

⑦ Check with fiber fineness meter, slice from the longitudinal and transverse sections of the yarn, and analyze whether there is any change or abnormality in the fiber structure, fiber state and blending ratio in the yarn. When slicing, use colored wool as the medium isolation of fibers. The thickness of the cut section is more appropriate and the image is more clear and distinguishable.

⑧ Preparation of solution for cellulose blended fabric containing spandex silk and dissolving its fiber insoluble spandex silk: 75mL of water is first injected into the beaker, then 25mL of 98% concentrated sulfuric acid is slowly injected along the glass rod, and then stirred continuously to prepare 40% sulfuric acid solution.

Pet-name ruby containing spandex cellulose blended fabric, dissolving its fibers but retaining spandex: put the elastic cloth sample into a beaker containing 40% dilute sulfuric acid, heat to 95 ℃ in a water bath, stir gently with a glass rod, it takes about 30min, pour out the solution, wear rubber gloves, clean the spandex cloth sample, and dry to check the cloth surface shape.

 

Summary

Because there are many factors that cause the formation of fabric crosspiece, its morphological distribution also has a variety of states, and the concealment is strong, the latent time is long, most of them will be obvious after weaving or dyeing and finishing. There are many methods to analyze the cross-section fabric defects, the analysis process is more cumbersome and complex, coupled with the industry chain cross-industry professional and technical analysis is more difficult, should be aimed at the specific situation of the circular fabric cross-section, do a specific analysis. The exclusion method can be used for item-by-item exclusion, and finally targeted forensics. Although the analysis of fabric rungs is complicated, there are not too many common types of rungs.
Strengthen the analysis and research of fabric crosspieces, understand the causes and solutions of circular fabric crosspieces in detail, master the analysis methods and operation steps, the generation of crosspiece defects will be effectively controlled, and the waste of crosspieces will be greatly reduced. From the industrial chain, raw materials, spinning, weaving, dyeing and finishing and other production links, combined with many factors that cause the fabric crosspiece, in view of the problems existing in the management of raw materials, equipment, technology, operation and so on, strengthen the management work, the emergence of crosspiece defects will certainly be fundamentally curbed.