Injection Molding
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Core shift of low density polyethylene injection mold causing uneven wall thickness
Problem Phenomenon
Product wall thickness is thick on one side and thin on the other; in severe cases, breakthrough occurs.
Core shift causes uneven wall thickness, affecting product strength and dimensional accuracy; common in long cores and slender products.
Cause Analysis
(1) Slender core with insufficient rigidity; bends and shifts under melt pressure
(2) Improper gate position; single-side feeding produces lateral unbalanced pressure
(3) Insufficient core support or insecure fixation
(4) Injection pressure too high or injection speed too fast; large melt impact on the core
(5) Excessive fitting clearance between core and cavity
Solution
(1) Optimize core design, increase core root cross-section or use high-strength mold steel
(2) Adjust gate position, adopt symmetrical multi-point gates for uniform mold filling
(3) Strengthen core support structure, ensure the core is firmly fixed
(4) Appropriately reduce injection pressure and injection speed, reduce impact on the core
(5) Control the fitting clearance between core and cavity within 0.02mm
Key Takeaway
Core shift is caused by insufficient rigidity or uneven force; it needs to be solved from core design, gate layout, and injection parameters.
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