I. Core malfunctions affecting dyeing quality
1. End marks (seam marks): Dark bands appear across the full width at both ends of the fabric; usually caused by excessively thick seams, excessive tension, or mismatched fabric-guiding parameters.
2. End-to-end shade variation: A noticeable difference in shade between the two ends of the fabric roll; associated with unclean guide rollers, uneven temperature control, or incorrect chemical dosing sequences.
3. Edge-to-center shade variation: Inconsistency between the color of the fabric edges and the center; caused by uneven fabric width upon entry, temperature or pH differences between the edges and center, or improper dye selection.
4. Left-center-right shade variation: Color differences across the width of the fabric (weft direction), manifesting as either dark edges or light edges; related to uneven winding, a mismatch between the enclosure temperature and the dye liquor temperature, or poor layout of the dye circulation piping.
5. Creases/Streaks: Longitudinal (warp-wise) crease marks on the fabric surface; caused by uneven seams, inconsistent raw fabric width, excessive steam impact, or improper tension adjustment.
6. "Tree-ring" marks (pressure marks): Tree-ring-like patterns on the fabric surface; caused by excessive tension or high temperatures during fabric winding.
7. Uneven dyeing (mottling/patchiness): Overall unevenness in shade; associated with low dye liquor levels, adding exhaustion accelerators too quickly, or failing to lower the temperature when adding chemicals during the process.
8. Shade bands: Transverse (weft-wise) bands of varying shades; usually caused by sudden machine stops due to mechanical failure.
9. Roll-to-roll shade variation: Significant color differences between different fabric rolls; caused by inconsistent process control, incomplete removal of unfixed dye, or lax sample matching.
II. Typical mechanical operation malfunctions
1. Steam pipe corrosion: Small holes in the direct steam pipe at the bottom of the vat become clogged or corroded by dye polymers in the bath over time; if the hole diameter increases, it causes localized unevenness in dye liquor temperature, leading to dyeing defects.
2. Roll diameter matching anomaly: As the roll diameter on the driving roller changes, the duration of contact between the fabric and the dye liquor fluctuates; this causes the leading section of the fabric to absorb excessive dye-resulting in a "dark head" defect-which is difficult to rectify during subsequent dyeing stages.
3. Housing seal failure: Inadequate sealing of the access door on atmospheric jig dyeing machines causes the temperature inside the housing to drop below that of the dye liquor; the resulting rapid cooling of the fabric edges prevents sufficient dye diffusion, leading to "light edge" defects.
4. Roller entanglement issues: Excessive accumulation of yarn waste around the stainless steel roller at the bottom of the vat disrupts the smooth movement of the fabric, causing defects such as creases or streaks.
