Prioritise Parameter Adjustment Criteria: If all of the following conditions are met, resolve the issue through temperature controller calibration and adjustment; thermocouple replacement is not required.
The thermocouple's physical appearance is intact; the protective sheath is free of corrosion and cracks; the armour wire shows no evident symptoms of breakage; and the sensing contacts have no oxidation spots, embrittlement, or crystallisation.
The multimeter test indicates that the circuit resistance is within normal range, the insulation resistance is ≥100MΩ, and there are no internal broken wires, insulation damage, or leakage issues.
Multi-point testing across the whole temperature range reveals a steady and stable temperature deviation with no jumps. The highest deviation is ≤±30℃, which may be rectified to an acceptable range using the Husky temperature controller's linear offset compensation feature.
The temperature response during heating is smooth, with no leaps or drift; the dynamic reaction time satisfies the technical requirements of the calibration number.
Strict Criteria for Immediate Replacement: If any of the following situations occur, replace the thermocouple with a brand new one; no adjustment is required.
During the insulating process, temperature fluctuations reach ±3°C, causing erratic readings. This implies an internal wire breakdown or loose connection fault that cannot be corrected through correction.
The maximum variation throughout the whole temperature range is >±30°C, surpassing the thermostat's ±50°C safety offset correction limit. Forced adjustments will cause additional system faults.
The thermocouple head is white, brittle, slag-covered, oxidised, or corroded. The thermocouple wire material has irreversibly degraded, rendering calibration and adjustment ineffective.
A slight vibration generates significant temperature fluctuations. This is a common early warning indication of failure, indicating inadequate internal electrode contact or incomplete wire disconnection. Continued use may result in complete thermocouple failure.
The cumulative usage duration has reached 80% of its lifespan, which means that more than three calibrations within a year have failed. Further modification costs more than 40% of the price of a new thermocouple; straight replacement is more cost-effective.
This set of judgement criteria allows for quick and precise decisions, taking into account both temperature measurement accuracy and operation and maintenance cost control, and is entirely compatible with the process requirements of Husky hot runner precision injection moulding.
