Molding Process
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PPS shrinkage and glass fiber
Problem Phenomenon
Product dimensional deviation; pure material shrinks greatly while glass fiber grades show obvious longitudinal and transverse shrinkage differences
Cause Analysis
Pure PBT shrinks greatly, PPS pure material shrinks about 0.2-0.7%, with 40% glass fiber the flow direction can be as low as 0.1-0.3% while the transverse direction remains higher; anisotropic shrinkage is the root of warpage and dimensional deviation
Solution
①Mold allowance according to grade shrinkage data; ②glass fiber grades calculated separately in longitudinal and transverse directions; ③precision parts corrected after mold trial; After adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability
Key Takeaway
PPS shrinkage shows strong directionality due to glass fiber orientation; directional allowance is the basic skill of mold design; After confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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