Material Analysis
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PPO Melt Near-Newtonian Fluid Characteristics
Problem Phenomenon
【Problem Phenomenon】Using increased shear rate to improve PPO filling is ineffective, and flow improvement is limited
Cause Analysis
PPO has poor flowability and is a near-Newtonian fluid; viscosity is relatively sensitive to temperature but insensitive to shear; increasing speed and shear helps little in reducing viscosity, and raising temperature is the effective means
Solution
Improve flow mainly by adjusting temperature: raise both melt temperature and mold temperature; wall thickness design not less than 0.8mm; enlarge runners and gates to reduce resistance rather than relying on shear; after adjustment, continuously sample to verify the effect, and resume mass production after confirming stability
Key Takeaway
PPO as a near-Newtonian fluid responds to temperature, not shear; raising temperature is the right way to reduce viscosity; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence; include this case in the defect archive as a troubleshooting reference for subsequent similar problems
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