Whether a hot runner system can continue to be used after exposure to moisture depends on the measured value of its insulation resistance: If the measured value is >1 MΩ, cautious, short-term operation is permissible, provided that monitoring is intensified; if the value falls between 100 kΩ and 1 MΩ, a risk exists, and the system must be shut down immediately for remedial action; if the value is <100 kΩ, use is strictly prohibited, as doing so carries a high risk of triggering short circuits, component burnout, or safety accidents.
1. Usage Recommendations Based on Moisture Severity
|
Insulation Resistance Value |
Usability |
Risk Level |
Recommended Action |
|
> 1 MΩ |
Usable (Short-term) |
Low Risk |
Intensify temperature control monitoring; schedule a thorough drying process during the next planned shutdown. |
|
100 kΩ – 1 MΩ |
Suspend Use |
Medium-to-High Risk |
Immediately cut off power; clean and dry the system at a low temperature; resume operation only after re-testing confirms the resistance meets safety standards. |
|
< 100 kΩ (or Approaching Zero) |
Strictly Prohibited |
Extremely High Risk |
Damaged components must be replaced; forced startup is strictly forbidden. |
Industry Safety Baseline: According to electrical safety codes, any insulation resistance reading below 1 MΩ is considered abnormal. Given the often harsh operating environments of hot runner systems, even stricter standards should be applied.
2. Why You Should Not "Operate with a Fault"?
Risk of Leakage and Arcing: Energizing the system in a humid environment can easily generate electrical arcs at connection points, potentially igniting plastic residue or hydraulic oil.
Vicious Cycle of Carbonization: Localized electrical discharge can carbonize surrounding materials, creating conductive pathways that further degrade the insulation integrity.
Production Disruption via Sudden Tripping: A sudden short circuit during operation can bring the entire production line to a halt, requiring a repair time of 4 to 8 hours or more.
Escalating Safety Hazards: Operators face a significant risk of electric shock when coming into contact with an energized mold-a danger that is particularly acute in humid environments. 3. Prerequisites for Safe Operation
If the measured insulation resistance exceeds 1 MΩ and no visible traces of moisture are present, and if temporary operation is absolutely necessary, the following conditions must be met:
Use a 500V DC megohmmeter to verify that every heating channel meets the required standards;
Clean the connector terminals to remove any oil residue or moisture;
Assign a dedicated attendant to monitor the unit for the first 30 minutes after startup, observing for any abnormal noises, smoke, or temperature irregularities;
Arrange for a thorough drying process or replacement of the unit to be completed within 24 hours.
Note: Moisture ingress is not a "minor issue," but rather a precursor to equipment failure. Even if the unit remains temporarily operational, repairs must be completed within 72 hours to prevent the damage from becoming permanent.
