In Mold Pressure Sensing Architecture for Multi Cavity Tooling Setup
In-cavity piezoelectric pressure sensing setups in multi-cavity tools decouple fill control from hydraulic drift to minimize scrap and verify part density.
Volumetric Pack Control
Meaning
Process regulation methods in injection moulding maintain a constant volume of polymer melt in the cavity during the packing phase. A typical volumetric pack control system adjust the screw displacement rather than relying purely on pressure limits to fill the mould cavity. This approach ensures that the mass of plastic delivered matches the calculated volume of the part after shrinking.
It is restricted by the compressibility of the polymer melt.
Machine Operation
Switching from the injection phase to the pack phase requires precise coordination of screw velocity and position. Under volumetric pack control, the machine monitors the displacement of the screw to ensure that a precise volume of resin is delivered into the cavity. This method prevents over-packing and flash, which can occur when using pressure-only switchover methods.
It maintains a stable melt cushion across consecutive shots.
Density Profile
Homogeneous density distribution within the moulded part prevents regional warpage. Because polymer density changes with temperature and pressure, volumetric pack control stabilizes the volume of material forced into the mould as it begins to cool. This action compensates for shrinkage.
Part Consistency
High-precision moulding applications benefit from reduced variation in weight and size across production runs. When volumetric pack control is active, the variations in melt viscosity do not translate into fluctuations in part weight. This control mode is particularly valuable when processing regrind blends, where viscosity can vary between batches.
Reliable volume delivery ensures that the finished parts meet the specified tolerances, preventing downstream assembly issues in complex multi-component products such as medical devices or automotive housings where even a sub-millimeter deviation results in assembly failure.