Injection Molding
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Stress Whitening of PE Injection Molded Products
Problem Phenomenon
White marks appear on PE products at locations subjected to ejection, bending, or impact, obvious on dark-colored parts.
Cause Analysis
When local stress on PE exceeds yielding, internal microvoids/crazes scatter light and appear white; concentrated ejection force, assembly interference, and drop impact all induce it, similar to PP.
Solution
①Distribute the ejection force (enlarge the ejection area); ②Reduce holding pressure to decrease the clamping force; ③Avoid local overstress and sharp corners in the structure; ④Select stress-whitening-resistant grades; ⑤Optimize the assembly interference.
Key Takeaway
PE stress whitening is a clear alarm that 'the local area has yielded': distributing the forces concentrated at ejection, assembly, and structure can prevent it, with no need for concealment; it is also a free indicator for locating structural and assembly weak points — making good use of it can reverse-optimize the design.
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