I. Routine Temperature Control and Preventive Management: Weekly calibrate the temperature sensors of all hot runner nozzles to prevent temperature drift and maintain a stable temperature control accuracy of ±0.5℃ in each zone. This prevents localised low temperatures from resulting in delayed filling and increased melt viscosity.
Perform a temperature check of each zone in the hot runner system prior to each material change to prevent the occurrence of localised temperature failures prior to the subsequent resumption of production. This prevents the slow filling of cavities due to abnormal temperatures in a singular area.
II. Routine Maintenance of Gates and Runners: After every 5000 mould runs, cease production and remove the carbonised residue from the heated runner nozzle heads. This mitigates the occurrence of localised runner obstructions, which result in a decrease in the flow area, a corresponding cavity that is filling slowly, and an increase in feed resistance.
The gates should be disassembled and the wear and tear should be inspected every three months. To prevent localised gate shrinkage that could result in filling delays, ensure that all gates have a consistent cross-sectional area over the long term by replacing those with excessive wear. III. Solidification and Locking of Process Parameters
The injection moulding machine system is configured to retain all verified temperature control, injection speed, pressure, and needle valve timing parameters following the repair. To prevent misoperation that could disrupt the filling balance, unauthorised personnel are prohibited from arbitrarily adjusting these parameters.
A process parameter file that is exclusively designed for this mould has been established. The utilisation of established parameters in mold-change production eliminates the necessity for repetitive re-adjustments and prevents parameter mismatches that could result in slow filling.
IV. Early Warning and Daily Production Monitoring
The filling pressure curves of each cavity are monitored in real time by utilising cavity pressure sensors. The system will automatically issue an early warning if the filling time difference for any cavity exceeds 0.05 seconds. This feature enables proactive troubleshooting and prevents the fault from escalating.
The coefficient of variation (CV) of product weight in each compartment is monitored by weighing product samples every 2 hours. The machine is immediately halted for inspection if the CV value exceeds 2%, thereby completing pre-treatment before the slow filling fault fully manifests.
V. Management of Material and Mould Change Adaptation
A short-shot filling verification is conducted once more when basic materials with varying flowability are substituted. The temperature parameters of the corresponding cavities are adjusted to accommodate the viscosity characteristics of the new raw material, thereby preventing the sluggish filling of local cavities as a result of changes in raw material flowability. Perform a short-shot full-cavity filling check to verify the synchronised filling of all cavities before officially commencing full-load mass production, prior to resuming production from a long-term mould closure.
This preventative maintenance solution is optimally suited for your existing precision hot runner multi-cavity mould production line. Upon its implementation, it has the potential to enhance the stability of mass production by more than 90% by reducing the recurrence rate of sluggish filling failures.
