Extrusion & Post
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PMMA Extruded Sheet Stress Streaks
Fenómeno del problema
Sheets show stress streaks under polarized light, and crack along the streaks during hot bending or engraving.
Análisis de la causa
Mismatched extrusion haul-off and cooling freezes orientation stress in the sheet; too-low roll temperature and too-fast haul-off both increase residual stress.; During on-site troubleshooting, verify item by item according to this mechanism to avoid blindly adjusting the machine based on experience alone.
Solución
①Optimize three-roll temperature matching; ②reduce haul-off stress; ③anneal sheets; ④test stress distribution before processing.; After adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability.
Conclusión clave
The internal stress of extruded sheets affects secondary processing safety; stress testing and annealing are necessary preparations before further processing.; After confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence.
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