Cavity Pressure Telemetry Fundamentals in Fast-Cycle Moulding
Cavity pressure telemetry decouples fast-cycle moulding from resin viscosity shifts by driving switchover directly from real-time in-cavity melt fronts.
Piezoelectric Quartz Sensor
Meaning
Physical transducers use crystalline materials to generate an electric charge under mechanical load. A piezoelectric quartz sensor is the standard tool for measuring pressure inside an injection mould cavity. The quartz crystal is highly stable and does not require an external power source to function.
It reacts almost instantly to changes in pressure during the injection and packing phases.
Signal Generation
Stress on the crystal structure displaces ions and creates a charge on the surface. This charge is directly proportional to the force applied by the plastic. The piezoelectric quartz sensor provides a linear output over a very wide range of pressures.
Thermal Stability
Quartz maintains its properties even at the high temperatures found in polymer processing. Unlike other sensor types, it does not experience significant sensitivity shifts as the mould heats up. This makes it ideal for long production runs where thermal consistency is required.
Cavity Monitoring
Real time data from the sensor allows the machine to adjust the switchover point. By monitoring the peak pressure, the system can detect defects like short shots or flash before the mould opens. The piezoelectric quartz sensor is a primary source of data for automated quality control systems.