Multi-stage injection molding process parameter optimization and adaptive parameter adjustment based on external sensors

This study developed a multi-stage injection molding process parameter optimization procedure and established an adaptive parameter adjustment system, with external sensors (a tie-bar strain gauge and a nozzle pressure sensor) as the core monitoring tools. The core work included three key aspects: first, extracting characteristic values from sensor curves (such as nozzle peak pressure and total viscosity index) and defining them as online quality indexes for real-time process monitoring; second, sequentially optimizing seven critical process parameters—including injection speeds in three stages, V/P switchover point, holding pressure, holding time, and clamping force—to address product appearance defects; and third, developing an adaptive parameter adjustment system that adjusts the first-stage injection speed and V/P switchover point in real time based on online quality indexes to reduce product weight variability during continuous production. Experimental results demonstrated that the system reduces the coefficient of variation of product weight, while multi-stage injection molding effectively improved product appearance defects.