I. Typical Fault Types and Causes
1. Dark Marks at the Ends: Dark marks appear at both ends of the silk fabric, usually caused by excessively wide seams, excessive tension on the roller, or insufficiently short guide yarn, leading to fabric compression.
2. Uneven Color at the Ends: Inconsistent color at both ends of the silk fabric, commonly caused by unclean guide yarn, incorrect dye addition order, or unstable temperature control.
3. Color Difference at the Edges (Left, Center, Right):** Color differences between the edge and the center may originate from uneven roll width, clogged dye nozzles, uneven tension on the fabric stretcher, or inconsistent pH distribution.
4. Wrinkles and Weft Skew:
Wrinkles: Caused by uneven seams, excessive tension, or excessive yarn wrapping on the bottom roller of the dyeing machine.
Weft Skew: Caused by uneven fabric feeding or excessive water jet impact, resulting in skewed yarn strands.
5. Rose-ring pattern: This pattern resembles tree rings and is mainly caused by excessive tension and high temperature during winding. Cold water winding is recommended to alleviate this.
6. Color streaks and uneven coloring:
Color streaks: Insufficient dye dissolution, an insufficient liquor ratio, or improper use of auxiliaries can easily lead to uneven coloring.
Color streaks: Machine malfunctions causing dyeing interruptions result in horizontal streaks.
7. Color difference between front and back sides: This is often caused by insufficient dye penetration, uneven fabric roll tension, or roller pressure deviation. It can be improved by optimizing nozzle design and adding leveling agents.
II. Key Solutions
1. Equipment Maintenance: Regularly clean the dyeing vat, check the parallelism of the guide rollers and the patency of the filter, and ensure uniform pressure (deviation <5%).
2. Process Optimization: Control the heating rate to avoid uneven coloring caused by excessive heating; Use fully dissolved dyes and add penetrants (such as JFC) or leveling agents to improve uniformity; Pay attention to water temperature control when dyeing with reactive dyes (40–60℃ is recommended) to prevent hydrolysis.
3. Operating Procedures: Keep the fabric guide clean and of uniform texture; Implement edge-aligning fabric rolling and use photoelectric correction devices; Cover the machine during dyeing to reduce temperature differences caused by air movement.
