I. Signal Instability and Data Jumps
Symptom: The displacement value of the sensor output fluctuates frequently and irregularly, resulting in unstable readings.
Cause: The sensor's shielding wire is inadequately grounded, and there is substantial electromagnetic interference from inverters, motors, and other sources in the vicinity.
Solution: Ensure that the shielding layer is consistently grounded at one end; install a signal isolation barrier in the signal circuit to isolate the interference source. The data should stabilise following the troubleshooting process.
II. Value Offset and Zero-Point Drift
Symptom: The zero point drifts slowly over time when frigid; however, the measured displacement value deviates significantly from the theoretical calculation value after heating.
Cause: The sensor was not adequately preheated; the installation coaxiality deviation is excessive; the hot runner support has experienced only slight deformation as a result of the heat.
Solution: Prior to calibrating the zero point, preheat the sensor for 15 minutes. Adjust the installation angle to ensure that the probe is parallel to the hot runner plate. Recalibrate the two points to eradicate system deviation.
III. Inadequate Linearity During the Stroke
Symptom: The displacement output is considered normal in certain ranges, but it experiences abrupt changes in value in others, with a linear error exceeding 0.1mm.
Cause: The sensor probe and the heated runner plate are jammed; the follower shaft is not moving smoothly; and the internal brushes are worn.
Solution: In severe cases, replace the sensor's internal brush assembly; add a small quantity of high-temperature grease to the follower shaft; and remove foreign objects from the probe's movement path.
IV. Alarm Function Failure
Symptom: The system either fails to generate an alarm when displacement surpasses the specified limits or generates numerous false alarms when displacement does not exceed the specified limits.
Cause: The alarm threshold setting is unreasonable, and the signal response latency parameter is incorrectly configured.
Solution: Increase the filter intensity to effectively filter out minor interference signals and adjust the alarm threshold to 90% of the safety expansion gap to ensure accurate alarm triggering.
V. Interruptions in Signal Transmission
Symptom: The host computer is unable to read sensor data abruptly; communication is completely disrupted.
Cause: Unstable power supply voltage; shielding wire damaged by high temperature; loose wiring terminals.
Solution: Replace the high-temperature shielded cable, retighten the wiring terminals, and verify that the power supply voltage remains consistent within the sensor's rated range.
These are frequent high-frequency defects that occur during the commissioning of hot runner displacement sensors. Over 95% of commissioning abnormalities can be promptly resolved without necessitating a return to the factory for repair after these issues are addressed with the appropriate solutions.
