How to Repair Zero-Point Drift in Hot Runner Sensors

Zero-point drift can be fixed based on the circumstances and is brought on by sensor age or installation issues:

1. Mild Drift (first occurrence, deviation < 0.1%FS): Calibration is adequate for repair.

This is the most typical scenario, which is frequently brought on by variations in temperature or a small buildup of material:

To start, clean the sensor diaphragm's surface to get rid of any leftover material. Take care not to scratch the diaphragm as you gently scrape it off with a soft copper sheet.

After reaching working temperature, hold the temperature for half an hour. After fully depressurizing, wait ten minutes. The zero point should revert to normal after being recalibrated.

2. Moderate Drift: Compensation + Cleaning to Delay Aging if the deviation surpasses the limit once more during a month of calibration (0.1%–0.5%FS).

If age is causing the drift to recur:

To get rid of corrosion residue, remove the sensor and thoroughly clean the diaphragm. Use extremely fine metallographic sandpaper to gently polish any minor oxidation.

Turn on the system's automated zero-point adjustment feature after reinstalling and calibrating (supported by the majority of common injection molding machines). For three to six months, this will automatically counteract the steady drift and keep things operating normally.

3. Severe drift (deviation > 0.5%FS, exceeding the limit right after calibration): Replacement is advised; correction is not possible. This condition suggests that either internal components are damaged or the sensor diaphragm has aged and rusted. The state can only be temporarily maintained by any correction because the drift is irreversible. It will shortly surpass the limit once more. To prevent batch scrap from pressure misjudgment, it is advised to replace the sensor directly.