Regular calibration and preventive maintenance are essential for ensuring accurate temperature measurement, extending thermocouple service life, and maintaining consistent part quality in hot runner systems.
Calibration Frequency. Calibrate thermocouples every 6–12 months to maintain accuracy. Perform 3 cycles of 200°C to room temperature aging every 50,000 shots. Regular calibration helps detect drift before it causes production problems.
Field Calibration Process. Field calibration is divided into three core phases: pre-calibration preparation, actual calibration, and verification. Insert the cleaned thermocouple probe into the calibrator constant temperature hole sequentially, wait 5 to 10 minutes for temperature data on the controller to stabilize, and record the displayed reading compared with the standard calibrator real temperature value. Adjust the PID temperature compensation coefficient inside the corresponding hot runner controller and continuously observe 60-minute temperature stability.
Laboratory Calibration. Dry block calibrators or furnace calibrators are widely used for precision calibration. The thermocouple is placed in a stable temperature source alongside a reference standard sensor. The output is compared at multiple temperature points, typically 200°C, 300°C, and 400°C for typical hot runner ranges.
Zero-Point Correction. In formal calibration, the first step is to carry out room temperature zero-point correction. Place all thermocouples in the same stable room temperature environment, connect them to the unified temperature control terminal in turn, record the displayed temperature value of each thermocouple, compare it with the actual ambient temperature measured by high-precision instruments, and correct accordingly.
High-Temperature Verification. The second step is segmented high-temperature verification to ensure accuracy across the full operating range. For Husky systems, three-point calibration correction factors can be accessed through the thermostat main panel by entering the factory default maintenance password.
Preventive Maintenance. Regular preventive maintenance is far more cost-effective than reactive repairs, as it reduces the risk of unplanned downtime and extends the service life of thermocouples by up to 50%. Preventive maintenance activities include checking line connections regularly, calibrating sensors on schedule, and updating control parameters to ensure the long-term effective operation of the self-diagnostic function.
Self-Diagnostic Functions. Modern hot runner controllers feature self-diagnostic functions that detect thermocouple disconnection, open or short circuits in the heating circuit, temperature exceeding limits, abnormal temperature drift, and voltage abnormality. These faults trigger corresponding alarm codes to help operators quickly locate problems. The above faults can be viewed in real-time via the HMI interface using alarm codes and analyzed in conjunction with event logs.
Thermal Aging Management. Thermal aging is a natural process that affects all thermocouples. Regular thermal cycling aging tests help identify sensors that are approaching the end of their useful life. For best results, maintain detailed calibration records for each thermocouple, track drift trends over time, and replace sensors before they fail catastrophically.
