Prepare Before Calibration Ensure that the Class II standard thermocouple, the 0.02-accuracy low-potential DC potentiometer, and the handheld thermocouple calibrator are all within their metrological validity period. Prepare the required wiring tools and insulation protection.
Preheat the Husky temperature controller and hot runner system for 15 to 30 minutes. Ensure that the thermocouple connections are secure and not loose, the hot runner temperature field is stable, and there are no evident hardware flaws.
Temperature field and wiring arrangement Place the measuring ends of the standard thermocouple and the Husky thermocouple being calibrated at the same measuring position in the hot runner's constant temperature zone, ensuring they are in the same temperature fields.
Make a clear distinction between the thermocouple's positive and negative terminals. Connect both the ordinary thermocouple and the calibrated thermocouple to their respective measuring devices. Check the loop and insulation resistances to ensure there are no loose connections or short circuits.
Multiple Temperature Point Comparison and Acquisition:
Gradually increase the temperature from low to high. To guarantee a stable temperature field with a temperature change of ≤0.2℃/min, keep the temperature constant for at least 30 minutes after attaining the preset calibration temperature.
Use the standard-calibrated-standard forward and reverse cyclic reading sequence. Every temperature point should be measured at least four times. To determine the indication error, record the thermoelectric potential values of both the standard and calibrated thermocouples and average them.
Low-temperature calibration points below 300℃ can be compared to a second-class standard mercury thermometer in an oil bath with continuous temperature. The oil bath temperature change should be within ≤±0.1℃.
Error Correction and Parameter Settings:
Calculate the indicator error at each calibration point, translate it to a temperature offset correction value, and enter the appropriate temperature offset compensation parameters into the Husky temperature controller's calibration parameter setup interface.
After completing the parameter settings, launch the temperature controller's PID self-tuning program to adjust the system to the new thermocouple properties and optimise the temperature control curve.
For post-calibration verification, run a closed loop at a constant temperature for 30 minutes to ensure a temperature deviation of ≤ ±1℃ between the temperature controller and the standard thermocouple, as well as a temperature fluctuation range of ≤ ±1.
Complete the calibration record by entering equipment information, standard information, raw data for each temperature point, error correction values, and calibration conclusions. Sign and archive the record to generate a traceable calibration file.
This recalibration technique is fully compatible with Husky hot runner systems, and the calibration results meet national metrological criteria, immediately recovering the thermocouple's temperature measurement accuracy.
