I. Basic accuracy verification in cold state
Stability verification at zero points: After the hot runner has cooled to room temperature (25℃), verify that the sensor probe is entirely flush with the hot runner plate with a zero gap. Confirm that the zero-point drift is ≤0.05mm and that there is no slow shift by allowing it to stand for 15 minutes.
Full-range linearity verification: Select five calibration sites between zero and full scale in an even manner using a grade 0 standard gauge block. Confirm that the linearity satisfies the standard and that the error at all points is ≤0.1mm by comparing the sensor output value with the standard value of the gauge block at each point.
Verification of repeatability: Manually press the hot runner plate to complete three full-stroke forward and reverse movements. The three output values at the same displacement point have a deviation of ≤0.05mm, with no absent 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. A comparison was made between the measured and theoretically calculated thermal expansion values, which confirmed that the deviation was ≤0.2mm and that there was no numerical shift due to 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 repair and can be repurposed for the monitoring of hot runner thermal expansion displacement if all verification items satisfy the aforementioned accuracy requirements. The repair is considered incomplete if any item fails to satisfy the requirements. At this point, the sensor parameters must be re-adjusted or the sensor must be returned to the factory for secondary repair.
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 repair.
