I. Uneven Dyeing (Color Variation, Color Difference)
Main Causes:
Poor Dye Liquor Circulation: A malfunctioning circulation pump, blocked pipes, or damaged valves lead to uneven dye liquor distribution.
Inaccurate Liquor Ratio: Too low a liquor ratio results in insufficient fabric immersion; too high a ratio leads to low dye concentration.
Abnormal Temperature Control: A malfunctioning heating/cooling system causes temperature fluctuations exceeding ±2℃, affecting the dyeing rate.
Solutions:
Regularly clean filters and pipes, and check the circulation pump's operating status.
Precisely control the water addition; modern equipment can use an automatic water replenishment system.
Calibrate the temperature control probe to ensure the heating curve meets process requirements.
II. Fabric Wrinkling or "Chicken Claw" Marks
Main Causes:
Excessively Rapid Heating and Cooling: Forced cooling, especially at high temperatures (>100℃), leads to uneven fiber shrinkage.
Mismatch Between Fabric Speed and Liquid Flow: Improper nozzle pressure adjustment causes fabric to pile and rub within the cylinder.
Excessive fabric buildup in the storage tank: Fabric knots form in the tank, creating localized indentations.
Solutions:
Control the heating and cooling rate; it is recommended that the temperature change per cycle not exceed 1–1.5℃.
Adjust the nozzle pressure and main pump frequency to ensure smooth fabric flow.
Set the appropriate fabric capacity before dyeing to avoid overload operation.
III. Slow or Inability to Heate
Main Causes:
Insufficient steam pressure or clogged steam trap, affecting heat exchange efficiency.
Damaged steam control valve or incorrect temperature controller settings.
Air leakage in the tank or an open exhaust valve, causing heat loss.
Solutions:
Check if the steam supply pressure meets the standard (usually ≥0.6MPa).
Clean or replace the steam trap to ensure timely drainage of condensate.
Inspect the control valve and temperature control system, identify and seal any leaks.
IV. Low Cooling Efficiency (Slow Cooling)
Main Causes:
Insufficient cooling water pressure or excessively high water temperature (>25℃). Faulty Cooling Water Control Valve or Excessive Back Pressure in the Return Water Pipe:
Scale buildup in the heat exchanger affects heat exchange performance.
Solutions:
Ensure stable cooling water pressure and maintain water temperature below 25℃.
Clean the heat exchanger regularly to remove scale deposits.
Inspect the control valve and install a booster pump if necessary.
V. Excessive Foaming:
Main Causes:
Use of high-foaming auxiliaries or dyes, especially under high-speed circulation, easily generates foam.
Residual oil from fabric pretreatment emulsifies and foams at high temperatures.
Solutions:
Prioritize low-foaming or non-foaming auxiliaries.
Strengthen fabric pretreatment to reduce oil residue.
Add defoamer if necessary, but avoid excessive amounts that could affect dyeing quality.
VI. Nozzle Clogging or "Air Bubbling":
Main Causes:
Impurities in the dye liquor are not properly filtered, clogging the nozzles.
An improperly designed nozzle structure causes gas to accumulate and form an "air bulge," affecting dye liquor spraying.
Solutions:
Install a multi-stage filter at the feed inlet to prevent particulate matter from entering the system.
Optimize the nozzle structure, such as by adding a flow control plate to stabilize the flow field.
