I. Thermally Stable General-Purpose Materials (PP, PE, ABS, PS)
Heating Rate: Set to 3~4℃/min for rapid full-power heating with no risk of localized overheating.
Holding Time: Hold at 100℃ for 10 minutes, then hold at the lower limit of the processing temperature for 10 minutes. Total heating time can be reduced to within 45 minutes.
Inspection Frequency: Check temperature every 20 minutes. No high-frequency monitoring is required; temperature fluctuations should be controlled within ±3℃.
Adaptation Points: Maximizes the reduction of heating time. No additional special control is required. Material can be fed within 30 minutes after reaching the production temperature.
II. Medium Thermal Stability Engineering Materials (PC, PA6, PA66, PMMA)
Heating Rate: Set to 2~3℃/min. Full power output before 100℃, then power limited to 80% after 100℃.
Heating Duration: Hold at 100℃ for 15 minutes, then at the lower limit of the processing temperature for 15 minutes. Total heating time should be controlled within 75 minutes.
Inspection Frequency: After the temperature reaches the processing temperature range, check the temperature every 10 minutes to avoid localized overheating.
Compatibility Considerations: Before heating, ensure the material is fully dry with a moisture content ≤200ppm to prevent hydrolysis and degradation at high temperatures. The temperature must not exceed the material's recommended processing upper limit by 5℃.
III. Highly Degradable Sensitive Materials (PVC, POM, PET, TPU)
Heating Rate: Set to 1~1.5℃/minute. Full power output is prohibited throughout the process; power should be limited to 60%~70%.
Heating Duration: Hold at 100℃ for 20 minutes, then at the lower limit of the processing temperature for 20 minutes. Total heating time should be extended to over 120 minutes.
Inspection Frequency: After the temperature exceeds the material's safety threshold, check the temperature every 5 minutes, simultaneously monitoring odor and overflow status to identify early signs of degradation.
Compatibility Considerations:
PVC: Processing temperature must be strictly controlled between 160~180℃, and must not exceed 200℃ to avoid decomposition and release of hydrogen chloride.
POM: Material must be added within 15 minutes of reaching the production temperature to avoid prolonged high-temperature exposure that could lead to chain depolymerization.
PET: Before heating, ensure the material's moisture content is ≤50ppm to prevent hydrolysis at high temperatures that could cause molecular chain breakage.
IV. Special Scenario Adjustment Rules: In high-humidity, rainy environments, all materials require an additional 10 minutes of dehumidification and heat preservation at the 100℃ stage to ensure sufficient moisture removal.
When using hot runners with different numbers of cavities, in addition to the material-specific heating strategy, apply adjustment rules for the corresponding number of cavities' heating rate and holding time to balance temperature uniformity and heating efficiency.
If any signs of degradation appear during the heating process, immediately lower the hot runner temperature to below the material's glass transition temperature, quickly replace the melt in the runner with a special cleaning material, troubleshoot the problem, and then restart the heating process.
