Injection Molding
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Insufficient filling due to poor PPO flowability
Problem Phenomenon
Short shots and material shortage occur in the thin-wall areas and flow ends of PPO products, with limited improvement after increasing the injection pressure, and complex structural parts are especially difficult to fill.
Cause Analysis
The high melt viscosity and poor flowability of PPO are inherent material characteristics; the amorphous structure melt rheology is close to Newtonian fluid, and the viscosity reduction effect of raising temperature is limited; runners and gates that are too small further amplify the filling resistance.
Solution
①Increase the melt temperature and injection pressure to enhance the mold filling ability; ②adopt a high-pressure and high-speed injection process; ③design short and thick runners and appropriately enlarge the gate; ④switch to a high-flow modified grade when necessary.
Key Takeaway
The root of PPO filling problems lies in the material flowability; high pressure and high speed is the standard process orientation; designing the mold runners for high-viscosity materials is a prerequisite.; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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