Rung rails, also known as cross rails, are a defect in knitted products. Specifically, they refer to the uneven density between rows, different yarn thicknesses, different color shades, and different coil sizes on the surface of the fabric. Horizontal stripes formed that are not required for product design.
Usually caused by uneven yarn thickness, wrong yarn replacement, and between knitting loop systems Knitting rungs caused by uneven yarn tension or uneven yarn bending depth, uneven warp knitting let-off, etc. The occurrence of rungs in knitted fabrics not only reduces the quality and grade of the product, but also has a certain impact on the corporate image and reputation.
Classification of rung defects
According to the causes of weaving and printing and dyeing processes Because of the reason, the rungs can be divided into three categories: yarn due to rungs, weaving due to rungs, and printing and dyeing due to rungs.
According to characteristics, it can be divided into one-place rungs, multiple rungs, regular rungs, and color-difference rungs (gray fabric color-difference rungs and dyed color-difference rungs ).
Analysis of causes of crossbar formation
1. Spinning raw materials
1.1 Pure cotton product raw materials
The maturity and fineness of raw cotton are generally expressed by the micronaire value. The better the maturity, the better the micronaire. The larger the clone value, the worse the maturity, and the smaller the micronaire value. The maturity of fibers is different, and the dyeing adsorption properties of fibers are also different. The greater the difference in micronaire value, the greater the difference in maturity. Raw cotton with good maturity is bright white in color and absorbs darker colors. Cotton with poor maturity is dull white in color, absorbs darker colors, and has no luster on the cloth surface. Raw cotton with a large difference in micronaire value is used at the same time. When the raw cotton is not mixed evenly, it is easy to produce horizontal bars.
GB 1103.1-2012 “Cotton Part 1: Sawtooth Processed Fine Staple Cotton” stipulates that when inspected by batch, the main color grade accounts for 80% and above, and the remaining color grades are only related to Adjacent, with no more than 2 types and no more than 3 levels.
The regulations of the main color grade play a key role in the stability of the color grade of cotton batches and blended cotton in textile cotton blends. The main color level emphasizes that the remaining color levels are only adjacent to it, which determines that a batch of cotton reflectance and yellow depth indicators present a patchy distribution on the color grading chart.
This ensures that the color levels of the blended cotton are distributed in a continuous patch on the color grading chart, and the remaining color levels of one batch of cotton may overlap with the remaining color levels of another batch of cotton. The properties increase, reducing the scattering distribution of the blended cotton color grade in the color grading chart, and improving the consistency and stability of the blended cotton color grade.
When selecting raw cotton, the yellow depth of the batch is generally controlled within a 2-digit difference range to stabilize the quality of the cotton batch and ensure stable color absorption of the finished product.
1.2 Raw materials for chemical fiber products
Chemical fiber raw materials will be The color difference phenomenon of raw material yellow and white fiber is mainly manifested as whiteness difference, residual amount change, raw material batch difference in the production process, etc. When using general chemical fibers in batches, try to use raw materials from the same production line and with close production dates. Avoid differences in color absorption of raw materials caused by excessive time and changes in oil.
Due to the influence of color masterbatch, the color of dyed spinning varieties will vary from batch to batch of raw material dyeing. Different shades and color heads will cause color differences in the finished product, resulting in rungs.
2. Spinning
2.1 Raw materials are not evenly mixed
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Pure cotton varieties are affected by the growth of the natural environment and varieties. There are differences in grade, color, color absorption, etc. between batches. The raw materials need to be fully mixed to ensure that each proportion of raw cotton Even proportion.
The mixing of raw materials with different properties must be evenly mixed, because the dyeing and color absorption properties of various ingredients are different. If the mixing is uneven, the proportion of raw materials will be different, and the quality of the yarn will be inconsistent. Stable, resulting in differences in color absorption and easy to cause rungs.
2.2 First make, first use
Due to raw material inventory in spinning mills Not too much, usually around 10 days. Raw materials are placed in batches in chronological order, and the transition is gradual. The use of finished yarn also needs to be used in chronological order. If the sequence is not controlled, the time difference is too large. Due to differences in the transition of raw materials, the color of the finished yarn will also fluctuate.
2.3 Yarn indicators
Yarn indicators are generally controlled at a reasonable level Within the fluctuation range, whether it is too large or too small will produce differences in color absorption.
2.4 Raw material defects
Raw material defects mainly target chemical fiber raw materials. Some chemical fiber raw materials have defects due to production process problems. Defects such as glue blocks can be eliminated in the carding process. A small amount of thick filaments will be brought into the finished product during the spinning process due to their better spinnability. They are thicker than normal fibers and will appear on the cloth surface. The upper absorption color is relatively deep, and if such yarn defects are concentrated, rungs will also be caused.
2.5 Mechanical reasons
Due to mechanical drafting and winding components Defects produce defective yarns, which differ from normal yarn indicators. If the hairy end fibers are melted due to a defective traveler, resulting in lagging spindles, non-penetrating and regular rungs will be formed on the cloth surface.
3. Weaving
3.1 Uneven tension
During weaving, due to uneven yarn tension or inconsistent diameters of spandex cones, the yarn drawing process causes inconsistent elasticity, which will cause the fabric to become horizontal due to different resilience. files. When using non-spandex yarn, uneven tension will cause inconsistent yarn coil sizes and poor coil arrangement., special varieties use different flower bags according to different performances. Recycled flowers must be collected and stored in separate varieties to avoid foreign fibers.
(3) Each spinning machine is equipped with a flower return bag to store the spinning bellows flowers. The bellows flowers are required to be torn to a specified area, and the dirty flowers attached to the bellows wall, the cords and waste wires inside the bellows flowers must be picked up. Pick up the wire ring inside the bellows flower.
(4) The backsplash must be reused in strict proportion and evenly, not too much or too little, to ensure that the proportion of backsplash in the finished product is stable.
6. Ensure stable quality indicators
Control all aspects of the yarn The quality index must fluctuate within the allowable range, yarns beyond the control range are promptly removed, defective yarns are singled out, packaged separately, and used individually.
7. Prevent rungs caused by dyeing
(1) Carry out maintenance on dyeing and finishing equipment, stabilize equipment status, ensure uniform pressure on the press rollers, and rationally select the hardness of the rubber press rollers to ensure uniform pressure.
(2) Choose dyes reasonably and try to choose dyes with the same dyeing curve. Dyestuffs are classified and stored according to their place of origin and batch number. Laboratory tests, inspections and other tests are carried out in advance, and the color heads of each batch of raw materials are recorded to prevent color differences.
(3) Ensure the uniformity of fabric drying. After the fabric enters the hot air drying machine, the wind speed and temperature have an impact on the speed of water evaporation. The wind speed must be controlled so that the cloth surface temperature and heating rate are consistent, and the fabric drying speed is consistent. At the same time, avoid burning the cloth surface if the temperature is too high.
(4) Add reasonable additives during dyeing to ensure uniform color absorption and avoid displacement during the subsequent rinsing process.
The method of observing the rungs
Generally, the method of observing the rungs is The main methods include tiling method, light transmission method, facing light method, backlighting method, tilting method, etc. Obvious rungs can be seen at a glance, but for less obvious rungs, several methods often need to be used to determine.
Conclusion
The main reason for fabric rungs is the raw material The use, production process control and stability of various weaving process parameters. The analysis and control of fabric rungs is a systematic project. During the production process, every detail needs to be controlled, from the entry and delivery of raw materials, the quality indicators and management process control of each semi-finished product, the delivery and transportation of finished yarn, and the weaving in the weaving factory. , dyeing factories, printing and dyeing, etc., all highlight the importance of detail management.
The factors that cause fabric rungs also involve aspects such as “people, machines, materials, methods, and environment” in the production process. The specific analysis needs to take into account all specific aspects of actual production. Details can effectively control the production of fabric rungs. </p
