It is extremely time-consuming to disassemble intact hot runner nozzle or manifold only for checking suspected internal core wire breakage of mounted thermocouple on Synventive and domestic in-production equipment; standardized multi-step nondestructive field inspection procedure helps maintenance staff judge core wire breakage fault rapidly without mold splitting disassembly operation and greatly improves troubleshooting efficiency. The first inspection step disconnects thermocouple two terminals from control cabinet wiring terminal row completely and uses multimeter resistance gear to measure loop resistance value of positive-negative core wire; if resistance reading displays infinite open-circuit state steadily, internal core wire has thorough breakage somewhere along wiring path. When measured resistance is far higher than rated standard resistance of same specification intact thermocouple, it indicates core wire exists partial hidden fracture with intermittent contact, which easily generates occasional open-circuit abnormal reading under workshop vibration and temperature alternation.
The second auxiliary inspection adopts megohmmeter to test insulation resistance between core wire and outer metal sheath; if insulation index sharply declines meanwhile loop resistance abnormally rises, breakage position contacts inner sheath wall and forms irregular short-circuit leakage fault. After preliminary numerical measurement confirmation, carry out local segment temperature change test: use hot air gun to heat segmented outer wire from terminal toward probe direction step by step and observe multimeter resistance real-time fluctuation; sudden resistance jump position marks approximate core wire breakage location, realizing fault positioning without splitting hot runner structure.
Standard workshop equips multimeter and megohmmeter as routine fault inspection essential tools, compiling operational checklist of nondestructive detection steps posted beside control cabinet for novice maintenance personnel reference. Mastering such nondestructive testing method avoids blind unnecessary hot runner disassembly caused by subjective speculation, shortens equipment fault repair downtime and cuts extra mold assembly and debugging cost for molding enterprise effectively.
