How to Calibrate the Temperature Compensation Coefficient of a Hot Runner Sensor
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There are two methods for calibrating a hot runner sensor's temperature compensation coefficient: standard precision calibration and on-site quick calibration. Select the approach that best meets your requirements. The following are the precise steps:
1. On-site Rapid Calibration Method (easy to use, frequently used after sensor replacement)
No additional specialist equipment is needed, and it can be used to counteract interchangeability flaws following sensor swapping:
Verify Reference Conditions: To enable the hot runner temperature to attain thermal equilibrium, keep the mold closed, the heating on, and all parameters constant for at least half an hour;
Note Current Display Temperature: Note the current sensor display temperature, T<sub>display</sub>, once the temperature controller shows a steady temperature.
In contrast to the actual temperature correction,
Use the stable temperature of the current sensor as the reference, T<sub>actual</sub>, if there is already a calibrated sensor at the same hole position.
Use T<sub>actual</sub>, the set temperature when the product is qualified as the reference, in the absence of a reference.
Modify Compensation Coefficient: Determine the value of the compensation correction:
ΔT is equal to T<sub>actual</sub> − T<sub>display</sub>. Enter the correction value ΔT directly into the temperature controller's sensor compensation/calibration interface. Save the configuration.
Check the calibration outcomes: Wait ten minutes for the temperature to settle after making the modification. Verify that the difference between the reference temperature and the displayed temperature falls within the permitted range. The calibration process is now finished.
2. The Standard Precision Calibration Method (appropriate for high-precision situations and new model calibration)
Calibration accuracy is increased when a standard thermocouple is used as a reference:
Tools Preparation: a high-precision device with temperature acquisition capability and a pre-calibrated first-class standard thermocouple (accuracy > 0.1°C);
Test Hole Machining: Making sure the bottom of the hole approaches the sensor mounting position by machining a test hole that matches the standard thermocouple close to the sensor mounting hole at the hot runner nozzle location;
Temperature Stabilization: Increase the temperature to the standard manufacturing temperature by turning on the heater. Hold for 30 minutes to give the temperature time to fully stabilize;
Data recording: Note the temperature T<sub>display</sub> of the sensor that needs to be calibrated as well as the actual temperature T<sub>standard</sub> determined by the standard thermocouple;
Calculating and Setting the Compensation Coefficient: Correction Value
ΔT = T<sub>standard</sub> − T<sub>display</sub>. Enter and store this adjustment value in the temperature controller's compensation parameters;
Verification: Compare once more upon stabilization. The calibration is successful if the deviation is less than the permitted error for the relevant case. Readjust if the variance is still more than what is permitted.
