Molds & Tooling
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PVDF Shrinkage Directional Differences and Dimensional Design
Problem Phenomenon
【Problem phenomenon】PVDF products have inconsistent shrinkage in flow and transverse directions, round parts lose roundness, and flat plates warp
Cause Analysis
2-3% high shrinkage superimposed with crystalline orientation makes shrinkage show directional differences; uneven mold temperature further amplifies the bidirectional dimensional difference; During on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based solely on experience
Solution
Compensate the mold by directional measured shrinkage differences; homogenize mold temperature; glass fiber reinforced grades can reduce and homogenize shrinkage but chemical resistance changes must be verified; After adjustment, take consecutive samples to verify the effect, and resume mass production only after confirming stability
Key Takeaway
High shrinkage plus directional differences; PVDF mold compensation must use directional measured values; After confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence; Include this case in the defect archive as a reference for troubleshooting similar problems in the future
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