Meaning
Sensor measurements taken within the mould during the injection phase capture the real time force exerted by the flowing polymer melt against the steel walls. Monitoring the dynamic cavity pressure allows injection moulders to detect variations in viscosity and material batch quality. This measurement provides a direct window into the mould filling process.
Melt Behaviour
Injection speed and melt temperature influence how the polymer advances through the cavity channels. During this phase, dynamic cavity pressure rises as the flow front approaches the sensor location, reaching its peak at the moment of cavity packing. Fluctuations in this peak indicate changes in melt flow behavior.
Process Control
Advanced injection moulding machines use the signal from these cavity sensors to switch the machine from velocity control to pressure control. This automated switchover ensures that the transition happens at the same volume fill percentage, regardless of screw position or viscosity drift. It stabilizes the part weight across a multi cavity run, even when using high percentages of regrind material which normally introduce rheological variability.
Defect Reduction
Moulding runs often experience dimensional drift and flash when the internal pressure is unregulated. Utilizing dynamic cavity pressure feedback prevents overpacking and short shots by adjusting the holding pressure dynamically. This control reduces the rate of scrap and avoids costly post moulding inspections.
