Meaning
Force measurement devices convert mechanical deformation into proportional electrical signals to monitor structural stresses in processing equipment. Integrating a strain gauge sensor into mold cavity walls or ejector pins enables real-time tracking of internal melt pressure during injection and packing phases. Hydraulic machine pressure gauges measure oil pressure at the injection cylinder rather than true cavity conditions.
Moulding technicians use localized strain readings to detect pressure transmission variations caused by changing resin viscosity.
Transduction Mechanism
Piezoresistive metal foil elements bonded to elastic substrate materials deform when external pressure acts upon the sensor pin. This physical deformation changes the electrical resistance of conductive grid patterns wired in a Wheatstone bridge circuit. Precision amplifiers convert these minute resistance changes into readable voltage outputs corresponding directly to mechanical stress.
Temperature compensation features isolate mechanical strain signals from thermal expansion caused by hot polymer melt during continuous molding operations.
Cavity Monitoring
Direct pressure readings identify exact melt front arrival and packing peak conditions inside the mold. Installing a strain gauge sensor reveals instantaneous pressure drops across complex cavity geometry.
Process Control
Real-time signal feedback enables automatic switching from injection velocity control to packing pressure control. Variations in regrind ratio alter melt compressibility, shifting the peak strain signal recorded during cavity filling. Monitoring pressure curves prevents flash formation and sinks by compensating for batch-to-batch material variations.
Sensor data logs provide permanent quality records for critical medical and automotive plastic components.
