Based on your previous concerns about hot runner misalignment and abnormal glue discharge, the following parameters can be adjusted quickly to address drooling and stringing:
1. Quickly lower temperature parameters: Reduce the temperature of the hot runner nozzle tip by 5-10°C to rapidly increase the viscosity of the material at the gate, reducing the natural flow of molten material.
Simultaneously, slightly reduce the temperature of the hot runner manifold area by 3-5°C to prevent the material in the overall runner from becoming too thin, reducing drooling at its source.
2. Adjust pressure and timing parameters: Appropriately increase the injection retraction (glue extraction) distance by 2-5mm, using the local negative pressure created by the screw retraction to draw back excess molten material from the nozzle.
Advance the valve closing timing of the needle valve type hot runner. Immediately close the valve after the pressure holding period to cut off the connection between the runner and the cavity, preventing material from flowing out.
3. Optimization of Auxiliary Process Parameters
Reduce the temperature of the injection molding machine barrel front section by 3-8℃ to reduce the total amount of molten material entering the hot runner and lower the residual pressure inside the runner.
Appropriately extend the cooling time by 2-3 seconds to allow the material at the gate to cool and solidify rapidly, physically preventing drooling and stringing.
The above parameter adjustments can be verified step-by-step during trial molding without stopping the machine. Typically, drooling and stringing problems can be quickly eliminated after 10-20 molding runs.
