Capacitive Displacement Sensor

Measurement Physics

Monitoring the electrical capacitance established between the probe face and the target surface determines the gap distance. When the polymer web moves through the measurement gap, changes in material density or thickness shift the dielectric constant and alter the output signal. Industrial systems use these signals to detect thin spots before they lead to structural failures in downstream thermoforming processes.

Relying on electromagnetic fields rather than mechanical contact prevents surface scratching and static buildup on delicate optical grade films, which protects visual quality in clear sheets.

Moulding Application

Injection moulding operations use these sensitive instruments to monitor tie bar stretch and mould deflection during the high pressure packing phase. Measuring plate separation with sub micron accuracy helps the operator optimize clamp tonnage and avoid flash defects without overstressing the steel tooling. High clamp forces can damage the venting paths and lead to burn marks, while inadequate clamping results in out of tolerance parting line dimensions.

Ambient Influence

Temperature variations and ambient humidity can affect the measurement accuracy of these devices by altering the dielectric properties of the air gap. To secure reliable readings on the factory floor, systems must incorporate thermal compensation algorithms and maintain stable environments. Frequent calibration against certified master standards ensures that the instrument continues to deliver precise tracking across long production cycles.

Clean air purges around the sensor head also prevent plasticizer vapours and dust from interfering with the measurements.