Injection Molding
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LDPE '2079851475616104452 Shrinkage Allowance
Problem Phenomenon
LDPE injection molded parts have large dimensional deviation, and molds with allowance set for other polyolefins are not applicable
Cause Analysis
LDPE shrinks 2-5% and varies with density grade; mold allowance must be determined according to the specific grade density; correction after trial molding is more reliable than setting the full allowance at once
Solution
① Set mold allowance of 2-5% according to grade density; ② reserve trial mold modification space; ③ test and finalize after dimensions stabilize; after adjustment, take continuous samples to verify the effect, and resume mass production only after confirming stability
Key Takeaway
LDPE mold allowance is a function of density; the trial mold correction route is more practical than theoretical calculation; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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