Recalibration is mandatory after replacing the temperature equalization sensor to ensure the new sensor matches the system's dynamic model and achieves temperature control accuracy within ±0.3℃. This is especially crucial in Wuhan's high-temperature and high-humidity environment, where strict closed-loop management is essential.
1. Why is Recalibration Necessary?
Time Constant T Mismatch: The thermal response speed of the new sensor may differ from the original. If the dynamic compensation parameters in the controller are not updated, the AI model will make predictions based on incorrect assumptions, leading to overshoot or lag.
Primary/Backup Temperature Difference Baseline Shift: The difference between the primary and backup sensor readings may exceed limits after replacement. A new 24-hour data collection is required to generate a new baseline T base for dynamic early warning threshold calculation.
AI Health Weight Inaccuracy: The PHM system needs to reassess the stability of the new sensor. The weight of abnormal points should be automatically reduced to <0.3; otherwise, the prediction accuracy of virtual measurement points will be affected.
Engineering Demonstration: A medical company launched production without calibration, resulting in a first-run scrap rate as high as 41%. After recalibration, this rate dropped to 1.2%.
2. Core Calibration Steps (Mandatory After Replacement)
Step Response Test: Sudden increase in heat power; record the time required for the temperature to rise to within ±0.5℃ of the set value. This should be ≤120 seconds.
Update Time Constant T: Refit the measured curve and synchronize it to the LSTM+Kalman fusion model.
Reset Primary/Backup Temperature Difference Baseline T base: Collect 24 hours of steady-state data and generate a new baseline for dynamic threshold calculation.
PHM System Relearning: Trigger the automatic calibration process to update the health weights and virtual measurement point models at each location.
3. Post-calibration Verification Requirements
72-hour steady-state monitoring: Main/backup temperature difference < 0.5℃, no drift (> 0.5℃/h) or burrs (> 5℃/s);
Functional test passed: Simulated disconnection, the system switches to the backup channel within 0.5 seconds;
On-site comparison meets standards: Infrared thermometer readings on the nozzle's outer surface deviate from the system reading by < 3℃.
Operational closed loop: Generate an electronic "Replacement + Calibration History Card" to achieve full traceability from "replacement" to "verification".
