Meaning
High-precision piezoelectric sensor utilized in injection moulding measures the dynamic forces generated by the polymer melt within the mould cavity. A quartz transducer generates an electrical charge proportional to the applied mechanical pressure, allowing the machine’s controller to monitor the cavity pressure in real time. This sensor can withstand the high temperatures and pressures of the moulding process without drifting or losing sensitivity over millions of cycles.
The high-fidelity data it provides is essential for implementing advanced process control strategies such as decoupled moulding, which improves production yield.
Signal Generation
Mechanical stress applied to the quartz crystal shifts the lattice structure to generate an electric charge on its surfaces. This charge is routed through a high-insulation cable to a charge amplifier, which converts it into a high-level voltage signal that the machine controller can process. This rapid response allows the system to detect sub-millisecond pressure changes during the injection phase, enabling immediate intervention if limits are exceeded.
Installation Method
Positioning of the sensor is typically done behind an ejector pin or in a custom-machined pocket directly in contact with the melt. Placing the transducer behind an ejector pin protects the sensor face from the abrasive action of glass-filled resins, which extends its service life. This indirect measurement relies on the pin to transmit the polymer pressure to the quartz element.
Quality Control
Monitoring the peak cavity pressure during the holding phase allows the moulder to detect part weight and dimensional deviations instantly. If the pressure falls outside the established control limits, the machine automatically diverts the part to a scrap bin, preventing bad parts from being packaged. This real-time inspection reduces the reliance on manual sorting and post-mould measurements.
