Molds & Tooling
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PEI Excessively Fast Freezing and Insufficient Filling
Fenómeno del problema
PEI products have incomplete filling in thin-walled and long-flow areas; raising the melt temperature to fill the cavity instead causes degradation, and the process falls into a dilemma.
Análisis de la causa
PEI molding has a unique characteristic: the product freezes particularly fast; the melt front freezes quickly causing short shots; precisely because of fast freezing, PEI products rarely show obvious sink marks, but the filling window is extremely narrow.
Solución
①Increase the mold temperature (140~180℃) to make the product freeze slowly; ②improve the mold runner to ensure fast and uniform melt injection; ③injection speed at 50~80% of the screw's maximum speed; ④coordinate with a larger runner design.
Conclusión clave
PEI's fast freezing is a double-edged sword of the material: free of sink marks but difficult to fill; high mold temperature and fast injection are the correct countermeasures; raising melt temperature is the wrong path.; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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