Optimizing Thermoforming Process Windows Using Strain Hardening Rheology Metrics
Strain hardening rheology metrics define thermoforming process windows by predicting extensional melt strength to eliminate corner thinning and sheet sag.
Optical Pyrometry
Meaning
Radiant thermal energy detection allows for the non-contact measurement of surface temperature. Optical pyrometry identifies the spectral intensity of emitted infrared or visible light to calculate the heat of an object based on the Planck radiation law. Instruments perform this task by focusing a lens on the target area and comparing the brightness against a calibrated filament or digital sensor.
Polymer Thermalisation
Processing engineers monitor melt temperatures in injection moulding and extrusion to ensure flow consistency within the cavity. Optical pyrometry detects heat variance across the gate or along the die lip during start-up cycles. Moulders maintain narrow heat windows to prevent thermal degradation of sensitive resins.
Precise tracking of these values reduces occurrences of short shots or burned spots on the finished part.
Calibration Requirements
Accuracy depends upon the emissivity setting defined for the specific resin being processed. Metals exhibit different radiative properties than plastics, so the software must compensate for the material surface characteristics to yield a correct readout. Failure to adjust this parameter results in data that deviates from actual bulk melt temperatures.
Users verify readings against contact probes during cold starts to confirm the pyrometer alignment.
Instrument Dynamics
Sensors operate by receiving concentrated electromagnetic radiation from a target zone. Electronic circuitry converts this energy into a stable output signal. Faster response times permit the capture of heat flux during high-speed moulding cycles where temperatures fluctuate over a few seconds.
A fixed installation ensures repeatability across production batches.