Thermocouple wire uniformity directly affects the accuracy of temperature measurement. Inhomogeneity in composition, diameter, or microstructure can lead to nonlinear thermoelectric potential output, causing temperature control deviations.
1. Decreased Measurement Accuracy: Thermocouples rely on the Seebeck effect to convert temperature into thermoelectric potential, and their output must have a strict correlation with temperature.
If the wire composition is segregated (e.g., uneven chromium content in K-type thermocouples) or the diameter fluctuates by more than ±0.01mm, it will cause local thermoelectric potential anomalies, resulting in:
Single thermocouple output drift, measurement error >1℃;
Inconsistent response among channels in a multi-point temperature measurement system, leading to temperature field imbalance.
Standard requirement: Industrial-grade wire should comply with IEC 60584, with an allowable error within ±1.5℃.
2. Control System Instability:
Abnormal PID regulation: The control system receives incorrect temperature feedback, which may be misinterpreted as overheating or underheating, leading to overheating or underheating.
Frequent false alarms: Increased signal noise may trigger false alarms such as "over-temperature protection" and "sensor disconnection," disrupting production.
Fluctuations in plastic part quality: Inaccurate temperature control can easily cause defects such as cold material, charring, and uneven filling, affecting product consistency.
Typical manifestation: The WinCC monitoring platform shows temperature fluctuations in a certain area, while the actual mold temperature remains stable.
3. Reduced long-term reliability: Uneven filaments are more prone to grain coarsening and accelerated oxidation at high temperatures, leading to zero-point drift or sensitivity decay.
Sudden failure or slow response may occur after a period of use, increasing the risk of unplanned downtime.
Recommended operation: Perform point temperature calibration before installing new thermocouples to ensure consistency across all channels.
