Molds & Tooling
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PMMA Hot Runner Dead Corner Black Streaks
Problem Phenomenon
Black streaks appear intermittently on transparent products, disappearing for a while after hot runner cleaning and then recurring.
Cause Analysis
Material accumulated in hot runner dead corners degrades slowly and periodically releases carbonized material forming black streaks; PMMA transparent parts are highly sensitive even to trace carbonized material.; During on-site troubleshooting, verify item by item according to this mechanism to avoid blindly adjusting the machine based on experience alone.
Solution
①Thoroughly clean the hot runner; ②evaluate dead-corner-free hot runner modification; ③shorten residence time; ④establish black streak cycle records.; After adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability.
Key Takeaway
Intermittent black streaks point to hot runner stagnation; dedicated dead-corner-free hot runner systems are recommended for transparent parts.; After confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence.
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