The Standard Comparison Method (Core Judgement Method)
Connect a qualified Class II standard thermocouple to the hot junction of the Husky thermocouple under calibration. Place it in the hot runner's temperature sensor orifice. After 30 minutes of stabilising at a common production temperature, compare the two observed temperatures.
Accuracy is acceptable for temperature differences of < ±1℃. If the temperature difference exceeds the permissible error range for the corresponding thermocouple graduation, the accuracy is considered inadequate.
Comparisons must take place at three typical temperature points: 20%, 50%, and 80% of the measurement range. Only when the variations at all points across the temperature range are within acceptable limits is the overall accuracy deemed acceptable.
Temperature Control System Self-Verification.
After entering the calibration parameters, launch the Husky temperature controller's PID self-tuning program, raise the temperature to the usually used production temperature, and run it at a constant temperature for 2 hours.
Observe the thermostat's temperature curve. The temperature fluctuation range is ≤ ±1℃, with no leaps or unidirectional drift, confirming the system's temperature measurement stability fulfils standards.
Cold junction compensation verification: Test the cold junction compensation module in various room temperature conditions and compare the difference between the thermostat's displayed temperature and the standard temperature. The cold junction compensation error is less than ±0.1℃, showing the stage's accuracy satisfies the norm.
Additional performance verification:
Insulation resistance retest: Measure the resistance between the thermocouple's two electrode wires and the outside case. Confirm that the insulation resistance is ≥ 100MΩ and there is no signal divergence due to leakage.
Dynamic reaction testing involves rapidly heating to the target temperature. The thermocouple temperature display takes ≤ 15 seconds to achieve 90% of the steady-state value, demonstrating that the dynamic response fulfils the standard with no temperature measurement distortion due to hysteresis.
Heating-cooling hysteresis test: Take two measurements at the same temperature, once for heating and once for cooling. The difference between the two readings is less than ±0.5℃, suggesting that the thermal hysteresis error is acceptable.
The verification techniques described above completely conform with industrial metrological calibration standards and can 100% confirm that the accuracy of the calibrated Husky thermocouples meets the process requirements of hot runner precision injection moulding.
