Key measures for preventing moisture damage in hot runner systems include: enhancing sealing protection, controlling humidity levels in storage and operating environments, regularly inspecting the condition of connectors, implementing moisture-proofing procedures during shutdowns, and selecting electrical components with high protection ratings.
1. Strengthen Sealing Design and Maintenance
Use High-Protection-Rating Connectors: Select waterproof aviation plugs with an IP65 rating or higher to prevent moisture ingress between terminals.
Regularly Replace Sealing Components: Replace consumables such as O-rings and gaskets every 1–2 years-or more frequently in high-humidity environments-to ensure the airtightness of junction boxes and connectors.
Install Protective Covers: Fit splash-proof covers over terminal boxes within the mold installation area to prevent exposure to splashing cooling water or dripping condensation.
2. Control Environmental Humidity
Keep the Workshop Dry: Equip the injection molding workshop with industrial dehumidifiers to maintain relative humidity below 60%, particularly during the rainy season or in high-humidity coastal regions.
Prevent Condensation from Temperature Fluctuations: During weekend or overnight shutdowns, it is recommended to keep the mold in a "low-temperature holding" mode (e.g., set to 50–80°C) to prevent condensation caused by significant temperature differentials.
Store Molds Properly: Molds intended for long-term storage should be placed on dedicated racks in a dry, well-ventilated area, away from cooling water pipes and damp floors; place desiccant packets inside the molds if necessary.
3. Protection During Shutdown and Restart
Thorough Cleaning Before Shutdown: Upon the completion of a production run, thoroughly remove any residual cooling water, oil stains, and mold release agents from the mold surface to prevent moisture retention.
Power-On Drying Treatment: For molds that have been exposed to moisture or have been out of service for an extended period, perform a "low-current preheating and drying" cycle before resuming operation (e.g., set heaters to 100°C for 1–2 hours); however, ensure that a preliminary check of the insulation resistance yields a reading of no less than 100 kΩ to prevent short circuits.
Pre-Startup Insulation Check: Before every restart, use a megohmmeter to measure the insulation resistance; proceed with normal operation only after confirming that the reading exceeds 1 MΩ.
4. Selection of Moisture-Resistant Components and Materials
Use Moisture-Resistant Heating Elements: Select heating elements featuring a double-layer sealing structure or a moisture-resistant coating to enhance their resistance to humidity.
Employ Moisture-Resistant Insulated Wiring: Prioritize the use of silicone-insulated wires(rated for temperatures ≥ 300°C); these wires exhibit low water absorption and stable dielectric properties, making them ideal for use in humid environments.
Seal Terminal Boxes with Potting Compound: For wiring connections that do not require frequent disassembly, use Room Temperature Vulcanizing (RTV) silicone rubber for potting to significantly bolster overall moisture protection.
Tip: Moisture is often the "invisible culprit" behind insulation failures. By implementing systematic routine inspections and effective environmental management, the risk of sudden downtime caused by such issues can be drastically reduced.
