Overheating cracks drastically shorten mold life, leading to premature failure or even sudden collapse. This is because the cracks originate from irreversible damage such as grain boundary oxidation and localized melting, causing a complete loss of the material's load-bearing capacity.
1. Direct impact on mold life:
Lifespan reduction of over 50%: Overheating cracks can expand by more than 50% within 24 hours after welding, rendering most molds unusable before completing their first production cycle.
High risk of sudden fracture: Cracks propagate spontaneously without external load, making them prone to sudden collapse during service due to slight vibrations or sudden pressure changes.
Irreversible repair: Overheating cracks cannot be repaired by welding or heat treatment; the entire mold must be replaced, with no possibility of extending its lifespan.
Actual data: Once overheating cracks appear in H13 steel molds, the average lifespan drops from the normal 200,000 cycles to less than 30,000 cycles, a decrease of over 85%.
2. Indirect Impacts and Chain Reaction Risks
|
Risk Type |
Manifestation |
|
Production Interruption |
Sudden mold failure leads to production line shutdown, with repairs and mold replacements taking several hours. |
|
Quality Control Issues |
Crack propagation causes molding defects such as flash and material shortages, significantly reducing product yield. |
|
Safety Hazards |
High-speed ejection of fracture fragments threatens operator safety. |
|
Surge in Costs |
Frequent mold replacements increase material and maintenance costs; single accident losses can reach tens of thousands of yuan. |
Special Reminder: Overheating cracks are insidious and difficult to detect initially, often suddenly appearing during high-load operation, posing a significant hazard.
3. Loss of Long-Term Service Stability
Accelerated Thermal Fatigue: Cracks become stress concentration sources, rapidly propagating during thermal cycling and accelerating mold aging.
Irreversible Tissue Deterioration: The grain boundary oxide network continues to develop; even without immediate fracture, material toughness continues to decline.
Ineffective Repairs: Any welding or surface treatment cannot restore the integrity of the internal structure and may even induce new cracks.
Safety Principles: Once overheating cracks are confirmed, the mold should be immediately taken out of service and scrapped; continued use is prohibited.
4. Preventive Measures Recommendations
Select Overheat-Resistant Materials: Prioritize the use of high-stability steels such as PM-H13 and H13+Ti;
Strict Temperature Control Management: Hot runner operating temperature ≤ 600°C, heat treatment not exceeding 1150°C;
Regular Metallographic Inspection: Random inspection every 6–12 months, shortening to 3–6 months under high-load conditions;
Establish Lifespan Records: Record the number of heating cycles, maximum temperature, and production cycle for each mold to enable predictive replacement.
Practical Tips: New molds must undergo metallographic inspection before entering the factory to prevent use with defects.
