Based on the previously established three-level wear assessment standard for hot runner sheaths and the corresponding repair solutions for different wear levels, the need for sheath replacement can be determined through three dimensions:
Structural Damage Assessment: If the sheath shows significant deformation or cracking, with large areas of exposed metal substrate, and cannot be repaired by grinding and reshaping, replacement is immediately required.
Performance Failure Assessment: If, after multiple coating repairs, temperature measurement deviations exceed 2°C and insulation resistance remains below 0.5MΩ, and routine maintenance cannot restore performance, replacement is necessary.
Lifespan Threshold Assessment: If the sheath has been in operation for more than 8 years cumulatively, or for more than 4 years under high-fiberglass conditions, even without significant damage, it has entered the late aging stage, and preventative replacement is recommended.
If any one of these criteria is met, the repair cost of the sheath exceeds 60% of the cost of replacement; direct replacement can better avoid the high risk of subsequent adhesive leakage and short circuits.
