Key methods for preventing magnesium oxide insulation from getting damp include strictly controlling the storage environment, optimizing the sealing design, pre-drying before use, and selecting high-purity or surface-treated materials. The specific measures are as follows:
1. Storage and Transportation Protection
Maintain a dry and airtight environment: Control the storage temperature at 20–25℃ and the relative humidity at ≤40% to avoid moisture absorption, agglomeration, and surface hydroxylation.
Moisture-proof packaging: Use double-layer sealed packaging (inner PE bag + outer aluminum foil bag). For ultra-high purity products, nitrogen purging is recommended.
Avoid long-term storage: The longer magnesium oxide is stored, the higher the risk of conversion to Mg(OH)₂. It is recommended to purchase enough for use within half a month to one month.
2. Material Selection and Process Optimization
Select high-purity magnesium oxide: Products with a purity ≥99.9% have low impurity content (e.g., Fe₂O₃, CaO controlled at the ppm level), significantly reducing the risk of hygroscopicity and ionic conductivity.
Surface Coating Treatment: Magnesium oxide particles are coated with a silica film to form a dense protective layer, effectively preventing moisture intrusion. Magnesium carbonate core-shell structures or composite oxides (such as forsterite and spinel) are used for coating to improve water resistance.
3. Pre-installation and Use Treatment
Pre-drying before use: Heaters stored for extended periods should be baked at 150–200℃ for 1–2 hours to restore insulation performance. In cases of severe moisture absorption, deep dehumidification can be achieved by drying at 500℃ for 4 hours.
Avoid Contamination Contact: Wear dry gloves during operation to prevent sweat and oil from contaminating the magnesium oxide area at the lead wires.
4. Structural Sealing and On-site Protection
Enhanced Lead Wire Sealing: The wiring terminals of the hot runner heater must use high-quality sealing adhesive, silicone, or metal sealing structures to prevent moisture from seeping in along the leads.
Installation Environment Control: Avoid operation in high humidity (>80% RH) or environments with frequent temperature fluctuations to reduce the risk of condensation.
Regular Insulation Resistance Testing: It is recommended to measure insulation resistance quarterly. ≥100 MΩ is considered normal; below 10 MΩ requires immediate replacement.
Practice shows that a three-pronged approach of "high-quality materials + sealed design + standardized operation" can significantly extend the stable service life of magnesium oxide insulation.
