Preparation before calibration: Prepare a Class II standard K-type thermocouple that has passed metrological verification, and a low-potential DC potentiometer with an accuracy of 0.02. Confirm that all standard equipment is within its metrological validity period. Preheat the Husky temperature controller and hot runner system for 30 minutes. Confirm that the repaired thermocouple wiring is secure and not loose. Retest the insulation resistance to ≥100MΩ.
On-site calibration procedure: Tie the hot junction of the standard thermocouple and the repaired Husky thermocouple together and insert them into the temperature measuring hole of the main gate of the hot runner. Ensure that both measuring ends are completely in contact with the metal wall of the runner and are in the same temperature field.
Select 2-3 commonly used production temperature points in the hot runner (e.g., 200℃, 400℃, 600℃). Gradually increase the temperature from the low temperature to the high temperature, and hold each temperature point constant for 20 minutes, ensuring that the temperature field change is ≤0.2℃/min.
Perform four cyclic readings in a "standard-calibrated-standard" sequence, taking the average value and recording it as the measured temperature of the standard thermocouple. Calculate the indication error of the repaired thermocouple at each temperature point.
Enter the "Advanced Calibration" menu on the Husky temperature controller and sequentially input the error correction values for each temperature point into the system, generating a full-temperature-range linear compensation curve. Simultaneously, set the cold junction compensation parameter to the measured ambient temperature at the terminal block.
Activate the temperature controller's PID self-tuning function to adapt the system to the new temperature measurement characteristics of the repaired thermocouple and optimize the temperature control curve.
Post-calibration accuracy verification: Heat to the commonly used production temperature and maintain it for one hour. Randomly compare multiple temperature points using the standard thermocouple. Confirm that the full-temperature-range temperature measurement deviation is ≤ ±1℃, temperature fluctuation is ≤ ±1℃, and there is no drift or jump. This confirms the calibration is complete and the temperature measurement accuracy fully meets the standards.
This calibration process is fully adaptable to hot runner field scenarios and can be completed quickly without external metrology, ensuring that the repaired thermocouple fully meets the temperature control requirements of Husky hot runner precision injection molding.
