I. Adjusting the Heating Rate According to Material Thermal Stability Classification
High Heat-Resistant and Stable Materials (PP, PE, ABS, PS)
Material Characteristics: Thermal decomposition temperature is much higher than the conventional processing temperature; short-term overheating poses no significant risk of degradation.
Heating Rate Setting: 3~4℃/min, allowing 100% full power output throughout, maximizing the compression of heating time.
Adaptation Points: No need for deliberate speed control; simply monitor that the final temperature does not exceed the material's recommended processing limit by 10℃.
Medium Heat-Resistant Engineering Materials (PC, PA6, PA66, PMMA)
Material Characteristics: Overheating or prolonged high-temperature exposure will cause molecular chain breakage and performance degradation.
Heating Rate Setting: 2~3℃/min, rapid full-power heating up to 100℃, after 100℃, power is limited to 80% to avoid temperature overshoot.
Adaptation Points: Before heating, ensure the material is fully dry, with a moisture content ≤200ppm, to avoid localized hydrolysis caused by moisture during heating.
Highly Degradable Sensitive Materials (PVC, POM, PET, TPU)
Material Characteristics: Low degradation trigger temperature; rapid decomposition and potential safety risks occur even with short-term overheating.
Heating Rate Setting: 1~1.5℃/minute; power limit 60%~70% throughout; rapid heating is prohibited.
Adaptation Points: Once the temperature exceeds the material's safety threshold, check the temperature every 5 minutes to identify early signs of degradation.
II. Targeted Adjustments Based on Material Specific Properties
High Viscosity, High-Filler Materials: Reduce the heating rate by 20% from the base rate to avoid uneven heating of the melt within the flow channel, resulting in poor filling and dispersion.
Materials Containing Glass Fiber Reinforced: The heating rate can be increased by 10% from the base value. Glass fiber itself poses no risk of thermal degradation, so the heating pace can be appropriately accelerated.
Transparent optical grade materials: The heating rate is reduced by 30% to ensure absolutely uniform temperature throughout the runner system, preventing poor light transmission and stress marks caused by localized temperature differences.
III. Special Scenario Adjustment Rules
In high-humidity, rainy environments, the heating rate of all materials is reduced by 20%, and the holding time at 100℃ is extended to ensure sufficient moisture removal and prevent hydrolysis and degradation.
When used with ultra-large multi-cavity hot runners of 64 cavities or more, the heating rate of all materials is reduced by 30% above or below the base value to prevent excessive temperature differences between the inside and outside of the large-mass runner plate, which could lead to thermal deformation.
If the hot runner has previously experienced an over-temperature alarm, the heating rate of all materials is reduced by 50%, and temperature stability is continuously monitored. Once no abnormalities are confirmed, the rate is gradually restored to the standard rate.
