I. Core Logic of PID Parameter Adjustment
P (Proportional Band): The smaller the value, the faster the heating response; the larger the value, the better it suppresses temperature overshoot.
I (Integral Time): The smaller the value, the faster it eliminates steady-state temperature differences; the larger the value, the better it avoids temperature oscillations.
D (Derivative Time): The smaller the value, the weaker the ability to predict temperature changes; the larger the value, the better it suppresses temperature fluctuations in advance.
II. Targeted Adjustment Rules for Different Materials
High Heat-Resistant and Stable General-Purpose Materials (PP, PE, ABS, PS)
Baseline Parameters: P = 8~12%, I = 120~180s, D = 20~40s
Adjustment Direction: Prioritize improving the heating response speed. The P value can be taken as a smaller value within the baseline range; slight overshoot has no risk of degradation.
Medium-Heat-Resistant Engineering Materials (PC, PA6, PA66, PMMA)
Baseline Parameters: P=12~18%, I=180~240s, D=40~60s
Adjustment Direction: Balance response speed and stability. If overshoot exceeds 5℃, increase P value by 15% and extend I value by 25%.
Highly Degradable and Sensitive Materials (PVC, POM, PET, TPU)
Baseline Parameters: P=18~25%, I=240~360s, D=60~90s
Adjustment Direction: Prioritize temperature stability. Use a higher P value within the baseline range to completely eliminate the risk of over-temperature degradation.
Special Modified Materials
Glass Fiber Reinforced Materials: Based on the baseline parameters of the same substrate, decrease P value by 10% to adapt to faster thermal conductivity.
Optical-Grade Transparent Materials: Based on the baseline parameters of the same substrate, increase P value by 20% and extend I value by 30% to ensure a temperature difference of ≤±2℃ throughout the flow channel.
III. Dynamic Closed-Loop Adjustment Steps When the hot runner reaches 30°C from the target temperature, the automatic PID self-tuning of the temperature control box is initiated to generate basic parameters suitable for the current runner load.
Observe the temperature rise curve: If the temperature rise is delayed or fails to reach the set value for an extended period, decrease the P value by 10% and shorten the I value by 20%.
If the temperature fluctuates frequently with small fluctuations, increase the D value by 30% to suppress temperature fluctuations.
For ultra-large multi-cavity hot runners with 64 cavities or more, the P value of all materials is uniformly increased by 30% to avoid global temperature oscillations in large-mass runner plates.
