I. Source Control: Standardized Operating Procedures are the First Line of Defense
Over 60% of all malfunctions stem from improper operation or negligence in procedures; therefore, strict adherence to standardized operating procedures is essential.
1. Comprehensive Pre-Start Inspection: Before each operation, ensure that the temperature gauge, pressure gauge, safety valve, and other instruments are sensitive and effective; that the motor and circuits have no risk of leakage; and that the screens and filters are clean and unclogging. Ensure the cylinder head seal is intact and that screws are tightened diagonally to prevent air leakage and cylinder differential pressure.
2. Scientific Fabric Loading and Feeding Sequence: After the fabric enters the machine, run it at a low speed for 3-5 minutes to ensure smooth fabric flow before closing the door and adding feed. When adding feed, first add acetic acid to adjust the pH to 5-6, run for 10 minutes, and then add the diluted, pulped dye to prevent dye agglomeration.
3. Precisely Control Temperature Change Rate: During the heating phase, especially above 80℃, the rate should be controlled at 1-1.5℃/min to prevent uneven dyeing and color variations. Cooling should also be done slowly to avoid rapid cooling that can cause "chicken claw marks" (dye stains).
II. Strengthen Equipment Maintenance: Periodic maintenance is key to long-term operation. Establish a tiered maintenance system to ensure that "minor problems are resolved within the shift, and major problems within the month."
1. Daily Maintenance: Clean the filter screen (once per shift for medium-length fibers and once per day for polyester filaments), check valve patency, and inspect the sight glass for damage.
2. Monthly Lubrication and Tightening: Apply high-temperature lubricating oil to bearings, gears, and other friction parts. Check the tension of V-belts to prevent slippage or breakage.
3. Comprehensive Overhaul Every Six Months: Shut down the machine to inspect the circulating pump, heat exchanger, and electrical system. Verify pressure gauges and temperature sensors to ensure accurate and reliable data.
4. Annual Overhaul: Replace aging seals, inspect the stainless steel inner wall for corrosion, test the safety valve functionality, and ensure safety under high temperature and pressure.
III. Process Optimization and Chemical Management: The Fundamental Means to Reduce Chemical Failures
The selection of dyes, auxiliaries, and water quality directly affects dyeing stability.
1. Prefer Low-Fogging Auxiliaries and Dyes: Foam is one of the main causes of fabric clogging and nozzle cavitation. Disperse dyes and auxiliaries with low foaming properties should be selected. If necessary, defoamers should be added in stages to avoid excessive use that contaminates the fabric.
2. Strengthen Pretreatment and Control Oligomer Precipitation: Before dyeing polyester fabrics, solvent refining or alkali reduction treatment is recommended to remove surface oils and low molecular weight condensates, reducing the formation of white frosty patches after dyeing.
3. Reasonably Set the Liquor Ratio and Fabric Capacity: A liquor ratio that is too small (<1:6) easily leads to uneven circulation, while a ratio that is too large wastes resources. Generally, a ratio of 1:6 to 1:8 is appropriate. Fabric volume must not exceed equipment standards to avoid prolonged stacking and wrinkling.
IV. Real-time Monitoring and Emergency Response: Dynamic Protection for Prevention
Operators must monitor equipment operation status throughout the process and intervene promptly in case of abnormalities.
1. Continuous Observation During Operation: Monitor fabric movement through the glass viewing window to ensure it is stable and free from floating, tangling, or bottoming. If initial signs of fabric blockage are detected, immediately activate the backflushing and unblocking device.
2. Avoid Opening the Cap at High Temperatures and Rapid Cooling with Cold Water: After dyeing, samples should only be taken after the temperature has dropped below 85℃ and the pressure has returned to zero. Injecting cold water to cool the fabric at high temperatures is strictly prohibited to prevent equipment damage or uneven fabric shrinkage.
3. Thorough Cleaning is Essential for Dark-to-Light Color Conversion: When converting from dark to light colors, a thorough cleaning with caustic soda and detergent at 130℃ for 60-90 minutes is required to prevent residual dye from contaminating the light-colored product.
