The vast majority of hot runner sensors cannot be repaired after aging. It is recommended to replace them with new sensors of the same specifications. Only a few non-core aging faults can be temporarily addressed as emergency measures. Specific situations are as follows:
1. Why can't most aging sensors be repaired?
Aging of hot runner sensors (mostly K-type thermocouples or PT100 RTDs) represents irreversible deterioration of the core components of the probe:
The thermocouple wires of K-type thermocouples undergo compositional changes due to long-term high-temperature oxidation and corrosion, resulting in irreversible sensitivity decay;
The platinum wires of RTDs deform due to long-term thermal expansion and contraction, causing irreversible resistance drift;
Aging and damage to the insulation layer and decreased probe thermal conductivity are all signs of overall material aging, making it impossible to restore accuracy through repair.
Even if recalibration is attempted, it can only maintain accuracy temporarily. The deviation will amplify again after 1-2 weeks, failing to guarantee long-term production stability.
2. A Few Cases Requiring Emergency Repair
If the issue is due to aging/loosening of the wiring terminals, rather than aging of the probe itself, temporary emergency repairs can be performed:
After disconnecting the power, remove the sensor wiring terminals and sand down the oxidized pins.
Retighten the wiring and clean any oil or carbon buildup inside the terminal box.
After calibration, re-verify the temperature measurement deviation. If the deviation returns to within 5°C, it can be used temporarily, but replacement is still necessary later.
However, this situation does not indicate aging of the probe core; it is merely a problem with the external connecting components.
3. Recommended Proper Handling After Aging
Prioritize replacing with original equipment manufacturer (OEM) sensors of the same specifications to ensure matching installation dimensions and signal types, avoiding compatibility issues.
After replacement, re-verify the temperature measurement deviation. Once the frictional heat error is confirmed to be within +5°C, it can be put into production.
For sensors that have been used for 3-5 years, batch rotation is recommended to avoid batch quality issues caused by single sensor aging failure.
