How to Prevent Recurrence of Leakage After Repairing a Hot Runner Heater

I. Prevention During Installation and Assembly Enhanced Insulation: Install a 99.5% high-purity alumina insulating bushing between the heater and the hot runner metal housing to completely block the direct contact path between the heating wire and the metal housing. Moisture-proof Sealing of Terminals: Fill the heater terminals with high-temperature resistant silicone rubber sealant and double-wrap them with Raychem FEP three-layer fluoroplastic heat shrink tubing to prevent moisture and corrosive decomposition products from entering the terminals. Torque Control: Tighten the fixing screws diagonally to the standard torque during heater installation to avoid localized stress compressing the heater shell and causing the internal magnesium oxide insulation layer to crack. II. Prevention During Daily Operation Heating Rate Control: When starting the hot runner, strictly adhere to a linear heating rate of 50℃/h. Prohibit rapid heating at full power to prevent the rapid vaporization of water inside the heater from breaking down the insulation layer. Environmental Humidity Control: The humidity in the production workshop is controlled between 40% and 60%. During long-term shutdowns, the hot runner is kept at 100℃ for 2 hours weekly to prevent the heater insulation layer from absorbing moisture over time. Power Supply Fluctuation Protection: A regulated power supply and a 30mA leakage current circuit breaker with a tripping threshold are installed at the heater's front end to prevent power grid surges from damaging the insulation layer. The circuit breaker automatically cuts off high-voltage power upon leakage. III. Regular Maintenance and Inspection Prevention Quarterly Synchronous Inspection: Every 3 months, synchronized with the Husky K-type coupler probe calibration, a 500V megohmmeter is used to test the heater's insulation resistance across all channels. An early warning and intervention is initiated when the insulation resistance falls below 5MΩ. High-Temperature Dynamic Spot Check: After each heating to the rated operating temperature and holding for 2 hours, the dynamic leakage voltage of the heater casing is checked using an AC millivoltmeter. Any abnormal voltage ≥1V is investigated promptly. Regular Replacement of Aging Components: After the heater has accumulated more than 8000 hours of operation, aged components are replaced in batches to prevent short-circuiting and leakage caused by prolonged high-temperature aging of the heating wire. IV. Supporting System Optimization and Prevention Cable Upgrade and Replacement: Replace ordinary heating cables with double-shielded, high-temperature resistant PTFE insulated wires to prevent leakage caused by long-term high-temperature aging and damage to the cable insulation layer. Grounding Loop Break: Optimize the grounding layout of the hot runner system. The heater shielding layer and sensor shielding layer are connected to the ground independently to prevent the superposition of ground loop currents that corrode the insulation layer. Regular Reapplication of Thermal Grease: Replace dried and aged thermal grease in the hot runner system every 6 months to ensure uniform heat dissipation from the heater and prevent localized overheating that accelerates insulation aging.