A damaged temperature sensing wire will directly lead to uncontrolled hot runner temperature, potentially causing serious defects such as material shortage, flash, and scorched material. The core of emergency handling is rapid diagnosis, temporary replacement, and safe restoration to minimize downtime losses. The following is a systematic emergency operation guide:
I. Immediate Response and Safe Handling
Stop and Disconnect Power
If an abnormal temperature is detected (e.g., -273.15℃ or full scale), immediately stop the injection cycle and turn off the power to the hot runner controller to prevent material degradation or equipment damage due to erroneous temperature control.
Identify the Faulty Channel
Affix "Fault Awaiting Repair" labels to the control panel and mold to avoid accidental operation.
Preliminary Damage Assessment
If the multimeter measures a resistance of "∞" → Open circuit
If the resistance is close to 0Ω → Short circuit
If the fluctuation is severe → Poor contact or shielding failure
II. Temporary Response Plans (Select based on site conditions)
Table Emergency Scenario Handling Method Risk Warning
With spare temperature sensing wire Replace with the same model PT100 sensor → Wiring → Resistance retest → Power-on test run Model matching must be confirmed; non-standard cables are strictly prohibited.
Without spare wire but with calibrator Use a temperature calibrator to simulate a standard PT100 signal (e.g., 200℃ corresponds to 175.8Ω), connect to the controller to maintain basic temperature control. Only for temporary production maintenance; not for long-term use.
Only for short-term operation If it is a multi-cavity mold and not a critical area, the temperature of adjacent areas can be appropriately increased to compensate for heat and reduce the injection speed. May lead to uneven filling; only for emergency shipments.
Controller supports manual setting Set the faulty area to "constant heating" mode (no feedback control), combined with infrared temperature monitoring of surface temperature. Extremely high risk, requires dedicated personnel to monitor and prevent overheating.
Prohibited Actions:
Short-circuiting the sensor input terminal with copper wire (will trigger a high-temperature alarm)
Blindly adjusting PID parameters to mask problems
Forcibly applying power without confirming insulation
III. On-site Quick Repair Suggestions
Check Connectors and Wiring
Remove terminals and check for oxidation, burning, or loosening.
Clean contacts with anhydrous alcohol, re-tighten, and seal with heat shrink tubing.
Segmental Troubleshooting
Cut the outer sheath at the middle position and measure the resistance before and after.
If the front section is normal, the damage is near the probe end → complete replacement is recommended.
If the rear section is abnormal, try cutting off the damaged section and re-connecting it (welding and insulation are required).
Emergency Grounding of Shielding Layer
If the fluctuation is caused by interference, a wire can be used to lead the shielding layer separately to the control cabinet grounding terminal to achieve single-point grounding.
IV. Key Actions After Production Resumption
Operational Monitoring
After startup, continuously observe the temperature curve for the first 5 cycles to ensure there is no drift or sudden jump.
Infrared Comparison Verification: Measure the nozzle surface temperature using an infrared thermometer. The deviation from the controller reading should be ≤ ±3℃.
Arrange Formal Replacement and Calibration: After emergency handling, the original factory temperature sensing cable must be replaced as soon as possible, and multi-point calibration must be completed to avoid potential problems.
Tip: It is recommended that the workshop keep 2–3 universal PT100 temperature sensing cables and quick connectors on hand for emergency replacement, minimizing downtime.
