I. Fundamental Signal Status Verification
Stable Signal Output: The sensor's 4~20mA analogue output is continuous and uninterrupted throughout the entire range. A multimeter reading indicates a signal deviation of ≤0.1mA, with no garbled characters, absent data, or skipped readings.
Normal Communication Link: The sensor and the host computer/PLC maintain a consistent level of communication throughout the entire process. There are no communication interruptions or data latency issues, and real-time displacement data is displayed synchronously without delay.
II. Verification of Cold State Accuracy
Zero-Point Stability Complies with Standard: The zero-point drift is ≤0.05mm after the hot runner has been allowed to stand at room temperature for 15 minutes, and there is no gradual offset.
Standard-Meeting Full-Range Linearity: The linearity requirements are satisfied, as the measured displacement at all five calibration points across the full range deviates from the sensor output value by ≤0.1mm.
The output value deviation at the same displacement point is ≤0.05mm after three full-stroke forward and reverse movements, with no random fluctuations. Repeatability meets the standard.
III. Performance Verification in the Hot State
Thermal Drift Compliance: The measured displacement value and the theoretically calculated thermal expansion value are within a 0.2mm margin of error, with no temperature drift, after the hot runner is heated to operating temperature and maintained for one hour.
Long-Term Stable Operation: The sensor displacement data remains consistent throughout a two-hour period of continuous mass production operation, with fluctuations of no more than 0.05mm and no abnormal jumps.
IV. Verification of the Effectiveness of Functional Interlocks
Accurate Alarm Function: The system activates the existing audible and visual alarms within one second when the displacement is within ±0.1mm of the preset alarm threshold, without any premature, delayed, or missed alarms.
Normal Interlock Action: The hot runner temperature control system receives the warning signal and automatically executes the heating and deceleration interlock action after the alarm is triggered, with a fully functional response.
V. Rules for Final Judgement
The hot runner displacement sensor can be considered successfully repaired and can be reintroduced to the production line if all of the aforementioned five verification items meet the requirements. However, if any item fails to meet the standard, the repair is incomplete and further investigation and processing are necessary.
This verification process is fully compatible with the low-cost Hall effect displacement sensor that you select, which is domestically produced. The repaired sensor can accurately warn of potential hot runner thermal expansion lock-up hazards, as ordinary maintenance engineers can complete the operation independently on-site.
