I. Basic accuracy verification in cold state
Zero-point stability verification: The sensor probe is fully integrated with the hot runner plate with a zero gap after the hot runner has been chilled to room temperature (25℃). It is permitted to remain in place for fifteen minutes. The zero-point drift is verified to be ≤0.05mm, with no slow shift.
Full-range linearity verification: Five calibration sites are randomly selected between 0 and full scale using a grade 0 standard gauge block. The standard value of the gauge block is compared to the sensor output value on a point-by-point basis. The linearity satisfies the standard, and the error at all points is confirmed to be ≤0.1mm.
Verification of repeatability: The hot runner plate is manually moved to execute three full-stroke forward and reverse movements. The three output values at the same displacement point have a deviation of ≤0.05mm, with no missing values or jumps.
II. Verification of Hot-State Accuracy
Thermal Drift Verification: The real-time displacement data of the sensor was recorded throughout the duration of the hot runner's operation, which was initiated and maintained at its rated operating temperature for one hour. The measured values of thermal expansion were compared to the theoretically calculated values, which confirmed that the deviation was ≤0.2mm and that there was no numerical shift caused by temperature drift.
Dynamic Stability Verification: The heated runner was maintained at the operating temperature for a duration of two hours. The displacement data output from the sensor remained consistent throughout, with no random jumps, and the data fluctuation range was ≤0.05mm.
III. Verification of Functional Linkage Accuracy
Verification of Signal Accuracy: The 420mA analogue output signal was verified using a digital multimeter. The experiment confirmed that 0mm displacement corresponds to 4mA and full-scale displacement corresponds to 20mA, with a signal deviation of 0.1mA and no signal transmission distortion.
Alarm Accuracy Verification: The system accurately triggered audible and visual alarms within ±0.1mm of the preset alarm threshold, without premature or delayed alarm phenomena, as per a manual simulation of a displacement exceeding tolerance scenario.
IV. Criteria for the Final Judgement
The sensor is considered to have met the necessary accuracy after calibration and may be repurposed for the monitoring of hot runner thermal expansion displacement if all verification items satisfy the aforementioned accuracy requirements. The calibration is considered incomplete if any item fails to meet the requirements. The sensor parameters must be re-adjusted, or a second calibration is necessary.
This verification process is entirely compatible with the low-cost Hall effect displacement sensor that you have selected for domestic production. The operation can be independently completed on-site by ordinary maintenance engineers, thereby guaranteeing long-term stable early warning of potential hot runner thermal expansion lock-up after calibration.
