Molds & Tooling
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PA66 ejector whitening and cracking
Problem Phenomenon
White marks and cracks at ejector pins, high incidence in deep-cavity parts.
Cause Analysis
Large gripping force + concentrated stress; insufficient cooling; PA66 has high rigidity and large gripping force; during on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based solely on experience.
Solution
①Extend cooling time so products are fully set before demolding; ②increase ejector pin number and area or switch to a stripper plate to distribute ejection force; ③appropriately reduce holding pressure to reduce gripping force and frozen internal stress; ④polish the cavity or die lip to reduce surface resistance and improve replication; ⑤optimize ejector pin layout.
Key Takeaway
PA66 ejector whitening='concentrated stress': distribute ejection force and give sufficient cooling; high-rigidity nylon ejection systems must leave sufficient margin; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence.
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