Injection Molding
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Insufficient rigidity of low density polyethylene injection products
Problem Phenomenon
The product deforms greatly under stress, with rigidity modulus lower than design requirements.
Insufficient rigidity causes excessive deformation during use, affecting function and safety; especially critical in structural parts.
Cause Analysis
(1) Low crystallinity of low density polyethylene, insufficient rigidity modulus
(2) Product wall thickness too thin or unreasonable rib design
(3) Mold temperature too low; cooling too fast, insufficient crystallization
(4) Barrel temperature too high; material degradation reduces molecular weight
(5) Improper material grade selection or insufficient reinforcing material addition
Solution
(1) Increase mold temperature to the higher value within the 30-60°C range, increase crystallinity
(2) Optimize product design, increase wall thickness or ribs, increase section moment of inertia
(3) Control barrel temperature at a reasonable value within the 160-220°C range
(4) Extend cooling time to ensure full crystallization
(5) Select high-stiffness grades or add nucleating agents; use reinforcing materials when necessary
Key Takeaway
Insufficient rigidity is caused by low crystallinity or unreasonable structural design; it needs to be solved from both process parameters and product design.
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