I. Determining Numerical Offsets
In typical industrial settings, an anomalous drift is defined as a zero-point offset more than 0.5% of the range.
When it comes to high-precision hot runner temperature control calibration, an offset that is more than 0.1% of the range needs to be addressed right away.
For instance, in a static state, an output current of >4.08 mA or <3.92 mA (theoretical value 4 mA) shows drift.
II. Determining Dynamic Output Anomalies
Without input, the output current exceeds ±0.1mA and varies erratically between 4 and 20mA.
The measurement error curve diverges rather than converges normally in the low-range region (less than 5% of the range).
III. Determining Environmental Correlation
Temperature Sensitivity: The drift increases dramatically to more than 200% of the typical temperature range or the reaction delay surpasses three seconds at high temperatures >60°C or low temperatures <10°C.
Mechanical stability: output variations more than 0.5% of the range as a result of shifting the vertical or horizontal mounting position; output fluctuations lasting more than 10 seconds following minor vibration (e.g., impacting the equipment casing).
IV. Time-Dimensional Drift Assessment
Short-term drift (within 24 hours): Any drift that is more than 0.3% of the range suggests a problem with the device or an uncontrollable environment.
Long-term drift (>6 months): Circuit ageing or flaws are indicated by linear growth >0.8% of the range/year or random fluctuation amplitude >1.2% of the range.
V. Verification Judgement After Calibration
Check the highest output difference after 30 minutes of standing following zero-point calibration. The equipment has a chronic drift issue if the difference is greater than 0.5% of the range, indicating that the drift has not been fixed.
Excessive thermal drift is indicated by a thermal sensitivity drift coefficient more than ±0.02%/℃ for industrial-grade hot runner signal generators.
This judgement approach may prevent erroneous calibration results of the hot runner temperature control channel due to signal generator drift, correctly detect the severity of drift, and drastically lower the incorrect judgement rate.
