Quickly Determine the Primary Cause of Drift
To rule out "false drift" brought on by inadequate heat conduction, make sure the sheath installation position is tight against the inner wall of the hot runner temperature sensing hole.
To rule out signal drift brought on by insulation damage or leakage during installation, remeasure the insulation resistance between the thermocouple poles and the sheath casing and make sure it is ≥100 MΩ.
To rule out drift brought on by the internal magnesium oxide insulating layer breaking owing to extreme bending, check the sheath's bending radius to make sure it is not tighter than the limit (twice the outer diameter).
On-Site Quick Repair Process
To prevent poor contact and electromagnetic interference, retighten wiring terminals, clean oxidised connections, confirm that the compensation wire calibration corresponds with the thermocouple, and make sure the shield layer is consistently grounded at one end.
Re-enter standard measured values for the hot runner's usual operating temperatures, access the calibration menu of the Husky temperature controller, and create a new single-point compensation curve specific to the thermal properties of the new sheath.
Start the PID auto-tuning feature of the controller so that the system may quickly adjust to the new temperature sensor circuit and remove drift brought on by mismatched parameters.
Verification of Restoration Outcomes
While keeping an eye on the temperature curve, heat the system to the typical production temperature and keep it there for thirty minutes. Verify that the temperature variation is ≤±1°C and that there are no random fluctuations or unidirectional continuous drift. Only then can regular manufacturing restart.
This restoration approach is ideal for hot runner post-installation maintenance since it swiftly fixes drift problems without requiring complicated steps, guaranteeing that the regular injection moulding production schedule is not disrupted.
