I. Pre-Heating Basic Optimization
Pre-calibration of the Temperature Control System: Calibrate all thermocouples for each channel, ensuring the temperature measurement deviation is ≤ ±1℃ to avoid temperature data distortion and fluctuations.
PID Parameter Tuning and Matching: Based on the quality of the hot runner plate and heating power, pre-tune the PID parameters for each channel to adapt to the current thermal inertia characteristics of the hot runner.
Check Hardware Connection Status: Ensure that the terminals of the heating coils and thermocouples are not loose or oxidized, and that the power supply voltage is stable within ±5% of the rated voltage to avoid temperature jumps caused by power supply fluctuations.
II. Stage-by-Stage Gradient Heating Control:
Low-Temperature Preheating Stage: Set the heating rate to ≤ 2℃/minute, slowly raising the hot runner temperature from room temperature to 30℃ below the material's heat distortion temperature to avoid uneven temperature caused by rapid heating and localized thermal expansion and contraction.
Intermediate Temperature Transition Stage: After heating to the lower limit of the material processing temperature, maintain the temperature for 20 minutes to ensure uniform temperature distribution throughout the flow channel plate and eliminate internal temperature differences.
Production Temperature Stage: Gradually increase the temperature to the set production temperature. Do not directly set the temperature to the maximum processing temperature at once to avoid overheating caused by full power output of the heating system.
III. Dynamic Management During Operation
Setting Reasonable Power Limits: Limit the maximum output power of each heating channel to within 70% to avoid large temperature fluctuations caused by full-power start-stop.
Reducing Ambient Airflow Interference: Turn off surrounding fans and air conditioners during heating to avoid direct airflow onto the hot runner surface, which could remove localized heat and cause temperature fluctuations.
Increasing Temperature Monitoring Frequency: After the temperature of easily degradable materials reaches the safe threshold, check the temperature of all channels every 5 minutes. Immediately adjust parameters to intervene if any fluctuations are detected.
IV. Targeted Optimization for Special Scenarios
Large Multi-Cavity Hot Runner: Adopt a zoned, staggered heating mode. Different heating zones start heating at different times to avoid instantaneous overload of total power, which could cause voltage fluctuations and abnormal temperatures throughout the system. High humidity environment: Extend the holding time appropriately during the heating phase to 100℃ to allow moisture to fully and evenly vaporize and dissipate, avoiding localized vaporization and heat absorption that could cause abnormal temperature fluctuations.
Aged hot runner systems: Replace aging heating coils and thermocouples in advance to prevent hardware performance degradation that could lead to unstable heating output, eliminating the root cause of temperature fluctuations.
V. Emergency Handling of Abnormal Fluctuations
If the temperature fluctuates continuously by more than ±3℃, immediately stop heating and check for issues such as sensor misalignment, loose wiring, and PID parameter mismatch. Resume heating only after troubleshooting to prevent material degradation caused by large temperature fluctuations.
