I. Hot Runner Storage Moisture Protection Specifications
Basic Storage Environment Requirements:
Ambient Temperature and Humidity: The storage environment temperature should be controlled between 15~25℃, and the relative humidity should be strictly ≤60%. Direct placement on the ground, near windows, or other areas prone to condensation is strictly prohibited.
Protective Packaging: Unopened brand-new hot runners should retain the original aluminum foil vacuum moisture-proof bag intact and sealed. Do not open the bag before the desiccant inside has expired.
Storage Method: Hot runner plates/nozzles with heating elements should be stored on elevated pallets, with the bottom raised by ≥20cm to prevent ground moisture from penetrating the insulation layer.
Regular Inventory Inspection Requirements:
Inspection Cycle: Inventory inspections should be conducted every 7 days. Record the ambient temperature and humidity, and check for any damage to the packaging or signs of condensation.
Insulation Sampling Inspection: For hot runners stored for more than 3 months, sample each batch and test the insulation resistance using a 500V megohmmeter. An insulation resistance ≥5MΩ is considered qualified.
Insulation Sampling Inspection: For hot runners stored for more than 3 months, sample each batch and test the insulation resistance using a 500V megohmmeter. An insulation resistance ≥5MΩ is considered qualified. Desiccant Replacement: For hot runners that are not immediately installed after opening, replace the silica gel desiccant with a fresh one every 15 days to prevent internal moisture absorption.
Special Protection for Long-Term Storage: Hot runners stored for more than 6 months should be resealed using vacuum packaging, with an additional desiccant of twice the weight, and affixed with a moisture-proof warning label.
It is strictly forbidden to pile water sources or moisture-containing materials around stored hot runners to prevent a sudden increase in local humidity.
II. Hot Runner Pre-Installation Baking Specifications
Pre-Baking Judgment Criteria: If the insulation resistance of the hot runner is <5MΩ after opening, or if it has been exposed to a humid environment for more than 2 hours, pre-installation baking must be performed.
During the rainy season and in humid conditions in southern China, regardless of whether the insulation resistance meets the standard, newly arrived hot runners must be baked before installation.
Stage Baking Parameter Standards
Low-Temperature Preheating Stage: Set the oven temperature to 80℃ and bake at a constant temperature for 2 hours. Slowly increase the temperature to avoid sudden thermal cracking of the insulation layer and remove most of the surface moisture.
Medium-Temperature Dehumidification Stage: Increase the temperature to 120℃ and bake at this constant temperature for 4 hours to thoroughly remove deep-seated moisture from the heating elements and wire gaps.
High-Temperature Curing Stage: Increase the temperature to 160℃ and bake at this constant temperature for 2 hours to cure the moisture-proof performance of the insulation layer, further improving insulation stability.
Baking Process Monitoring Requirements: Retest the insulation resistance every hour throughout the baking process. Baking can be terminated early if the insulation resistance is ≥20MΩ for two consecutive tests and the value remains stable without increasing.
During baking, all terminals of the hot runner should be kept suspended and should not directly contact the metal inner wall of the oven to avoid short circuits and component damage.
Post-Baking Installation Time Requirements: After baking, allow the hot runner to cool naturally to below 60℃ in a dry environment. Complete the installation and wiring within one hour to avoid prolonged exposure to a humid environment and secondary moisture absorption.
If installation does not occur within 2 hours of cooling, a second baking process at 120℃ for 2 hours must be performed to confirm insulation compliance before installation.
III. Post-Installation Moisture Protection Verification Requirements
After installation, the initial temperature rise must begin at 100℃ and hold for 1 hour before gradually increasing to the production temperature. This is to prevent residual moisture from instantly vaporizing and causing insulation breakdown.
During the temperature rise process, the high-temperature insulation resistance must be retested. Only after confirming a resistance ≥0.1MΩ should subsequent sensor calibration and trial production procedures be initiated.
