Meaning
In mould measurement instruments capture the real time physical conditions of the polymer melt during the injection cycle. A mold cavity sensor is installed directly within the mould steel to measure melt pressure or temperature as the material fills the cavity. These data points provide a direct look at how the polymer behaves under compression, bypassed by the delay of machine nozzle sensors.
Using these measurements allows the moulding machine to switch from injection to packing based on the actual state of the material rather than screw position.
Pressure Transduction
Piezoelectric crystals within the instrument generate an electrical charge when compressed by the advancing polymer melt. This charge is converted into a pressure curve that reveals the exact timing of the filling and packing phases. Any shift in this curve indicates a change in material viscosity or shot volume.
Process Correction
Comparing the active pressure curve with a master curve allows the machine controller to make immediate adjustments. If the pressure is too low, the controller can extend the packing phase to prevent the formation of sink marks or voids. This real time adjustment helps maintain part weight and dimensions even when the material viscosity fluctuates.
Part Validation
Automated sorting systems use the peak cavity pressure to decide whether a part is acceptable. Parts produced during a cycle where the pressure falls outside the established limits are automatically routed to the scrap bin by a diverter gate.
