Molds & Tooling
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PMMA Optical Lens Birefringence
Problem Phenomenon
Under polarized light inspection, lenses show abnormal birefringence fringes, and optical imaging quality fails.
Cause Analysis
Filling shear and holding pressure freeze highly oriented molecular chains, producing stress birefringence; improper gate design concentrates orientation in the optical zone.; During on-site troubleshooting, verify item by item according to this mechanism to avoid blindly adjusting the machine based on experience alone.
Solution
①Reduce injection and holding pressure stress; ②raise mold temperature to promote relaxation; ③optimize gate position and form; ④annealing treatment.; After adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability.
Key Takeaway
The birefringence of optical parts is directly related to stress level; gentle process plus annealing is a necessary means to ensure imaging quality.; After confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence.
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