This can be determined through three steps: visual inspection, signs of leakage, and signal changes. Replacement is necessary if any of these conditions are present:
1. Direct visual inspection after disassembly (most accurate): Observe the beveled seal after disassembly:
Obvious indentations, deformation, cracks, or localized corrosion pits on the beveled surface; Residual molten material crystals on the sealing surface cannot be completely cleaned, and the crystals are embedded in the sealing surface gaps; The original metallic luster of the beveled surface disappears, and obvious high-temperature oxidation discoloration and decreased hardness are observed. Replacement is necessary in any of these cases.
2. Observe signs of leakage during production: Leakage can be detected without disassembly:
Slight molten material leakage occurs at the mold parting surface or sensor installation location. Leakage recurs after cleaning and subsequent production; After startup and heating, a small amount of carbonized molten material residue appears at the sensor wiring terminals, indicating that the molten material has penetrated the seal and is leaking. Immediate replacement is required.
3. Monitoring Vibration Signal Changes
For online monitoring, abnormal signals can be identified:
A sudden, significant drift or irregular jump in previously stable vibration data, after ruling out sensor malfunction, is generally due to leaks in the seal causing the sensor to loosen.
A sustained, slow increase in the vibration baseline value indicates minor deformation of the seal and a continuous decrease in seal preload, requiring replacement.
If there are only minor scratches on the sealing surface, without leakage or abnormal signals, cleaning and reapplication of high-temperature graphite grease are sufficient for continued use; premature replacement is not necessary.
