Molding Process
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PEI Sharp Corner Stress Concentration
Problem Phenomenon
PEI products crack due to stress concentration at sharp corners; although the material toughness is acceptable, notch sensitivity makes sharp corners the starting point of failure.
Cause Analysis
Although PEI's elongation at break of 60~80% shows extraordinary toughness, it has notch sensitivity; product design must avoid sharp angles to reduce stress concentration in order to maintain maximum impact strength; sharp corners have high stress concentration factors.
Solution
①The design absolutely avoids sharp angles, with rounded transitions; ②snap-fit structures utilize toughness but require rounded corners; ③coordinate with low-stress processes; ④verify the design with notched impact.; after adjustment, continuously sample to verify the effect, and resume mass production after confirming stability
Key Takeaway
PEI's toughness and notch sensitivity coexist; rounded corner design is a prerequisite for exerting toughness; snap-fit structures are an advantageous application of PEI but require standardization.; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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