In-situ calibration technology for hot runners refers to the technique of directly calibrating the temperature sensors in the hot runner system on-site at the injection mold without disassembling the sensors, ensuring their accuracy in actual working conditions.
1. Core advantages of in-situ calibration
No need for machine shutdown and disassembly: Avoids production interruptions and mold damage caused by sensor disassembly, improving equipment operating efficiency.
Realistic working condition reproduction: Calibration is performed under actual operating conditions such as high temperature, high pressure, and high humidity (e.g., summer environment in Wuhan), resulting in more representative data.
Reduces thermal resistance error: Traditional offline calibration struggles to simulate the installation contact state, while in-situ calibration eliminates measurement deviations caused by aging thermal grease, loose threads, etc.
2. Mainstream in-situ calibration methods
(1) Portable constant temperature source comparison method: Uses a handheld miniature constant temperature bath (e.g., Fluke 710) and a standard platinum resistance thermometer (PT100 Class A) as reference sources, connecting them in parallel with the thermocouple being measured and inserting them into the same temperature measuring hole. The temperature control system's compensation parameters are adjusted by simultaneously recording the readings of both thermocouples and flow field using a multi-channel data acquisition instrument.
Suitable for on-site calibration of K-type and J-type thermocouples and PT100 sensors.
(2) Automated Intelligent Calibration System
Combining deep learning algorithms with combined probe technology (such as sonic-hotfilm anemometer), temperature and flow field are calibrated in tandem.
The system automatically identifies environmental disturbances (such as changes in airflow and humidity), dynamically optimizes the calibration curve, and improves long-term stability.
It is particularly suitable for high-precision closed-loop control scenarios, such as medical-grade injection molds.
(3) Distributed Fiber Optic Temperature Reference Method
A fiber optic sensor network is pre-embedded inside the hot runner plate as a distributed temperature reference benchmark.
Continuous temperature measurement across all channels is achieved using the Raman scattering principle, and the data is compared with that of point thermocouples to locate abnormal temperature measurement points.
It is often used for system-level calibration and fault diagnosis of large multi-cavity molds. 3. Calibration Cycle and Maintenance Recommendations
Routine Cycle: In-situ calibration is recommended every 6 months. The frequency should be increased during the rainy season or after high-load operation.
Key Performance Indicators:
Insulation Resistance ≥ 100 MΩ (to prevent leakage interference)
Zero-point Drift ≤ ±0.5℃
Response Time Variation ≤ 10%
Local Compatibility Note: High temperature and humidity in Wuhan can easily cause the magnesium oxide insulation layer to become damp. It is recommended to install a waterproof sleeve and seal the junction box after calibration.
Operational Recommendations: Prioritize intelligent temperature control boxes with self-diagnostic functions (such as Husky and Synventive systems), which support one-click in-situ calibration to reduce the risk of human error.
