Does the hot runner displacement sensor need to be recalibrated after calibration?

I. Fundamental Debugging Requirements
Accuracy Requirements: Zero drift controlled within 0.05mm, repeatability error ≤ 0.05mm, and full-range measurement error ≤ 0.1mm.

Signal Requirements: A signal response latency of no more than one second, and the transmission of a 4-20 mA analogue signal without any data loss or skipping.

Alarm Requirements: Within one second of displacement exceeding the limit, activate the current audible and visual alarm and simultaneously issue an interlock warning signal to the hot runner temperature control system.

Stability Requirements: The monitoring status remains stable throughout, and the displacement output data does not exhibit any drift after the hot runner is maintained at maximum temperature for 1 hour.

II. Standardised Operating Procedures
Signal Connection Verification: Ensure that the communication link between the sensor and the host computer/PLC is functioning properly and that real-time displacement data is displayed synchronously and without any communication interruptions or data garbling.

Use a digital multimeter to verify the 4~20mA output signal, ensuring that 0mm displacement corresponds to 4mA and full-scale displacement corresponds to 20mA, with a signal deviation of ≤0.1mA.

Full-stroke linearity retest: Manually press the hot runner plate to complete three full-stroke forward and reverse movements, recording displacement data point by point. This will confirm linearity throughout the entire stroke without abrupt changes or signal jumps caused by jamming.

Use a feeler gauge to verify the measured displacement values at three random locations, ensuring that the deviation from the sensor output value is less than 0.1mm and that the accuracy standards are met.

Thermal stability debugging: Begin the hot runner and heat it to the rated operating temperature. Maintain the temperature for one hour and monitor the displacement data of the sensor output.

Confirm a deviation of ≤0.2mm by comparing the real-time displacement value to the theoretically calculated thermal expansion value, ensuring that there is no numerical shift caused by temperature drift.

Alarm interlock debugging: Manually simulate displacement scenarios that exceed the tolerance limit by setting the displacement over-limit alarm threshold to 90% of the safe expansion clearance of the hot runner.

The temperature control system automatically implements a temperature rise and deceleration interlock to prevent rapid heating of the hot runner and potential lock-up upon confirmation of immediate audible and visual alarm triggering. A warning signal is received.

Verification of long-term operation: The hot runner is operated continuously for two hours after it enters normal mass production. This confirms that the sensor monitoring data remains consistent throughout the duration of the operation, with no abnormal false alarms or missed alarms.

Debugging records are generated and archived, and all debugging parameters are saved, thereby concluding the entire debugging process.

This debugging process is entirely compatible with the Hall effect displacement sensor that you have selected, which is a low-cost, domestically produced sensor. This guarantees the long-term stability of the calibrated sensor and the accurate early warning of potential hot runner thermal expansion lock-up.