The core principle for the emergency handling of reduced insulation in a hot runner system is: immediately cut off power and isolate the system, quickly pinpoint the fault location, temporarily resume production (if feasible), and maintain detailed records to facilitate subsequent thorough repairs.
Step 1: Immediate Shutdown and Power Disconnection
Turn off the power supply to the temperature control unit, and disconnect the hot runner system from the main control cabinet to prevent the fault from escalating or triggering short circuits or fires.
Place a "Do Not Energize" warning sign on the power distribution cabinet to ensure operational safety.
Step 2: Preliminary Assessment of Fault Scope
Check the temperature controllers to see if they are displaying fault codes for overcurrent, leakage, or short circuits.
If multiple heating zones are showing anomalies simultaneously, prioritize checking the main power cable, central junction box, or common ground wire for signs of moisture ingress, carbonization, or water damage.
Step 3: Segmented Measurement of Insulation Resistance
Use a megohmmeter (500V DC) to perform the following tests:
Measure the resistance-to-ground for each heating rod individually;
Test the cable harness first, followed by the connectors, and finally the heating element body itself, to pinpoint the source of the leakage;
Record the resistance value for each circuit; a reading below 1 MΩ indicates an anomaly, while a reading below 100 kΩ requires immediate deactivation of that circuit.
Step 4: Temporary Remedial Strategies (Select Based on Circumstances)
Single-point failure in a non-critical channel: The affected heating zone can be temporarily disabled (masked); production may continue for a short period by reducing the injection speed (though product quality risks must be evaluated).
Issues with the main cable or junction box: If a spare cable harness is available on-site, it can be quickly swapped in; otherwise, a full shutdown for maintenance is recommended.
Mild leakage caused by moisture (resistance values between 100 kΩ and 1 MΩ):
Disconnect the connectors and clean the terminals using anhydrous alcohol;
Dry the components using a heat gun (ensure the temperature does not exceed 80°C);
Retest the insulation resistance to confirm it has recovered before attempting to resume operation.
Step 5: Resume Operation and Monitoring
After restoring power, do not engage high-voltage injection immediately; instead, run the system under no-load conditions for 30 minutes to observe whether the temperature stabilizes.
Use an infrared thermometer to verify that the temperature difference between any two nozzles does not exceed ±10°C.
Designate a specific individual to stand by during the first two molding cycles to confirm the absence of smoke, abnormal noises, or further circuit tripping.
Note: This emergency procedure serves merely as a "stopgap fix"; a thorough inspection and component replacement must be scheduled and carried out within 72 hours to prevent recurring malfunctions.
