I. General Inspection Frequency for All Stages of Hot Runner Heating
Ambient Temperature → Low-Temperature Preheating Stage (Ambient temperature to 30°C below the material's heat distortion temperature)
General Inspection Interval: Every 30 minutes
Inspection Content: Record the heating rate of each channel, confirm no local overheating, and observe the nozzles for any abnormal material overflow.
Medium-Temperature Transition Stage (30°C below the heat distortion temperature → Lower limit of the material's processing temperature)
General Inspection Interval: Every 20 minutes
Inspection Content: Confirm that the overall temperature of the hot runner is uniform, with no temperature plateaus and no abnormal odors.
Production Temperature Holding Stage (Lower limit of the processing temperature → Setting and holding the production temperature)
General Inspection Interval: Every 10 minutes
Inspection Content: Monitor the temperature fluctuation range to ≤±2°C, observe the melt state at the nozzles, and confirm no signs of degradation.
II. Specific Inspection Intervals for Different Easily Degradable Materials
PVC (Polyvinyl Chloride): During the full heating phase, the inspection interval is uniformly shortened to 10 minutes. Once the temperature exceeds 160℃, the inspection interval is further shortened to 5 minutes, focusing on monitoring for signs of degradation such as acidic odor and yellowing melt.
POM (Polyoxymethylene): Before the temperature reaches 180℃, inspect every 20 minutes. After the temperature exceeds 200℃, the inspection interval is shortened to 5 minutes, focusing on monitoring for irritating formaldehyde odor and spraying risks.
PET (Polyethylene Terephthalate): Before the temperature reaches 240℃, inspect every 20 minutes. After the temperature exceeds 260℃, the inspection interval is shortened to 8 minutes, focusing on monitoring melt transparency and signs of hydrolysis silver streaks.
TPU (Thermoplastic Polyurethane): Before reaching 200℃, inspect every 20 minutes. After exceeding 220℃, shorten the inspection interval to 10 minutes, focusing on monitoring melt yellowing and bubble overflow.
PC (Polycarbonate): Before reaching 280℃, inspect every 30 minutes. After exceeding 300℃, shorten the inspection interval to 10 minutes, focusing on monitoring for black spots and early signs of silver streaks.
III. Special Scenario Inspection Adjustment Rules: In high-humidity environments such as the rainy season/return to spring, shorten the inspection interval for all easily degradable materials by 30% to prevent moisture from accelerating material degradation.
For large multi-cavity hot runner systems, add additional inspection of the runner plate surface temperature, with an inspection interval not exceeding 15 minutes, eliminating blind spots caused by localized hot spots.
If an over-temperature alarm occurs during the heating process, shorten the inspection interval for all subsequent stages to 5 minutes, continuously monitoring until the temperature is completely stable.
