Material Analysis
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Utilization of PSU Shear-insensitive Characteristic
Problem Phenomenon
[Problem Phenomenon] Attempting to improve PSU flow by increasing shear rate; poor effect and shear heat damage
Cause Analysis
Unlike most polymers, PSU melt viscosity is relatively insensitive to shear; increasing speed and shear has limited help in reducing viscosity; low molecular orientation also makes product performance less affected by flow direction
Solution
Adjust flow mainly by temperature rather than shear; expand the process window along the temperature axis; use the low-orientation characteristic to simplify directional design; after adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability
Key Takeaway
PSU is shear insensitive; raising temperature is the right way to reduce viscosity; speed increase yields little benefit; After confirming effectiveness, solidify the parameters and practices into the work instructions to prevent recurrence; Include this case in the defect archive as a reference for troubleshooting similar problems in the future
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