I. Pre-calibration Preparation
Tools and Qualification Confirmation: Prepare a CNAS-calibrated multi-channel high-precision temperature monitoring instrument, a 500V digital megohmmeter, a 0.8 N·m torque screwdriver, high-temperature thermal grease, high-temperature resistant polyimide tape, and heat-insulating gloves.
Confirm that the calibration personnel are qualified to operate the hot runner temperature control system. Retrieve the historical calibration log for this Husky hot runner system in advance, confirming the channel numbers and corresponding temperature measurement points of all sensors.
Equipment Pre-Check: Turn off high-power start/stop equipment around the hot runner in advance to avoid grounding loop interference with the temperature measurement signal.
Confirm that the Husky temperature controller has no abnormal alarms such as heater overcurrent or sensor open circuit, and that the equipment is in a normal operating condition capable of heating up.
Short-Peak Pre-Heating: Utilize non-production breaks to heat the hot runner from room temperature to 280°C and hold. 30 minutes before calibration, heat to 320°C and hold for 2 hours until the overall temperature of the runner is completely uniform and stable.
Staggered Pre-Heating: Utilize non-production breaks to heat the hot runner from room temperature to 280°C and hold. 30 minutes before calibration, heat to 320°C and hold for 2 hours until the overall temperature of the runner is completely uniform and stable.
II. Sensor Pre-calibration Steps
Appearance and Mechanical Inspection: Inspect each channel of the thermocouple probe for bending, no green corrosion or wear through the armor layer, and no oxidation or burning on the connector pins. Ensure the probe is fully inserted into the bottom of the sensing orifice without any gaps.
Tighten all sensor mounting screws to 0.8 N·m using a torque screwdriver to prevent probe loosening or displacement.
Insulation Performance Test: Use a 500V digital megohmmeter to test the insulation resistance between the thermocouple core wire and the armor layer, and between the thermocouple core wire and the hot runner housing, channel by channel. An insulation resistance ≥ 5 MΩ at room temperature is considered qualified.
After holding the hot runner at 320℃ for 2 hours, retest the high-temperature insulation resistance. Confirm that the insulation resistance is ≥ 0.1 MΩ, indicating no potential insulation failure at high temperatures.
Basic Signal Verification: Use a multimeter in millivolt range to test each channel of the thermocouple circuit. Confirm that the circuit is continuous and without open circuits. The deviation between the output thermoelectric potential at the cold junction at room temperature and the theoretical value on the K-type thermocouple standard calibration table should be ≤ 0.05 mV.
III. On-site Data Acquisition Steps
Standard Probe Fixation: Secure the standard temperature probe of the temperature monitoring instrument to the corresponding hot runner temperature measurement point surface using high-temperature resistant polyimide tape, ensuring complete contact between the probe and the metal surface of the runner without gaps.
After all standard probes for all channels are fixed, wait 15 minutes for the probe temperature to fully synchronize with the runner temperature.
Parallel Data Acquisition: Start the multi-channel temperature monitoring instrument, set it to acquire one set of data per minute, and continuously and automatically acquire 10 sets of synchronous temperature measurement data for all channels.
Run the pre-written Python automatic sampling script, directly connecting to the Husky temperature controller via PTP industrial communication, synchronously and automatically acquiring sensor temperature measurement data from the temperature controller, eliminating the need for manual recording.
Data Validity Screening: Remove abnormal data jumps caused by equipment start-up and shutdown interference during the acquisition process, retaining 10 sets of continuous and stable valid temperature measurement data, and calculate the average deviation between the standard value and the sensor temperature measurement value for each channel.
IV. Husky Thermostat Parameter Correction Steps
Access Calibration Menu: On the Husky thermostat control panel, enter the administrator password to access the "Sensor Calibration" menu and select the channel requiring calibration.
Confirm that the cold junction compensation reference value for the current channel matches the measured room temperature value to avoid introducing additional errors through cold junction compensation.
Compensation Parameter Setting: Input the inverse value of the calculated average deviation for each channel as the temperature compensation parameter into the calibration offset field for the corresponding channel.
For systems with 8 or fewer channels, compensation parameters for all channels can be directly imported in batches. For systems with 16 or more channels, ensure that the parameters for each channel correspond one-to-one with the acquired data to avoid channel misalignment.
Save and Apply Parameters: After confirming that all channel compensation parameters have been entered, click the "Save and Apply" button. The thermostat will automatically load the new calibration parameters, complete the cold junction compensation reset, and the sensor temperature measurement data will be immediately updated synchronously.
V. Post-Calibration Stability Verification Procedure
Accuracy Re-verification: After the parameters take effect, wait 30 minutes and then synchronously collect 5 sets of temperature measurement data again. Confirm that the temperature measurement deviation of all channels is ≤ ±1℃, with no jumps or drifts.
Manually increase and decrease the set temperature by 10℃ three times each, observe the PID adjustment process, and confirm that the temperature overshoot is ≤ 2℃ and returns to the set value within 3 minutes.
Long-Term Stability Verification: Run continuously at the set temperature for 1 hour, monitoring the temperature measurement data of all channels throughout the process. Confirm that the temperature fluctuation range is ≤ ±0.5℃, with no irregular jumps.
Simulate the start and stop of surrounding high-power equipment to confirm that the sensor temperature measurement data has no instantaneous jumps and is not affected by grounding loop interference.
Trial Production Final Verification: Start low-speed trial production and continuously produce 20 modules of products. Monitor the sensor temperature measurement data and heater current dynamic changes throughout the process, confirming no overcurrent alarms and no abnormal signal interruptions.
Inspect the appearance and dimensional accuracy of the trial production products to confirm the absence of defects caused by flash, insufficient glue, uneven stress, or temperature anomalies, ensuring that process stability fully meets standards.
VI. Calibration Closed-Loop Archiving Steps
Automatic Data Upload: Automatically upload all original data collected during this calibration, compensation parameters, and verification results to the existing MES system, generating a compliant calibration report with CNAS traceability.
Automatically update the full lifecycle maintenance log for the Husky hot runner system sensors, recording the calibration time, deviation value, and next calibration cycle for each channel.
Dynamic Cycle Adjustment: For sensors with three consecutive calibration deviations < ±0.5℃, automatically extend the calibration cycle from 3 months to 6 months.
For sensors with a calibration deviation exceeding ±2℃, mark them as key monitoring targets; temporarily shorten the subsequent calibration cycle to 2 weeks, gradually restoring the original cycle after two consecutive calibration deviations stabilize.
