Injection Molding
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Large creep deformation of general-purpose polyethylene injection molded products
Fenómeno do problema
The product deforms slowly under long-term load, and the deformation gradually increases over time.
Creep deformation affects the dimensional stability and service life of the product, and is especially critical in long-term load-bearing products.
Análise das causas
（1）General-purpose polyethylene has low crystallinity, and the molecular chains are easy to slip, resulting in large creep
（2）The product wall thickness is insufficient, and the high stress level accelerates creep
（3）The use temperature is high, and the creep rate increases when it is close to the glass transition temperature of the material
（4）The molecular weight of the material is low, and the creep resistance is poor
（5）The product design does not consider the long-term creep margin
Solução
（1）Raise the mold temperature to the higher value within the range of 30-80°C to increase the crystallinity
（2）Increase the product wall thickness or reinforcing ribs to reduce the use stress level
（3）Control the use temperature within the long-term temperature resistance range of the material
（4）Select high molecular weight grades or add reinforcing materials to improve creep resistance
（5）Consider the creep margin in product design, and leave the creep deformation amount in the initial dimensions
Conclusão principal
Creep deformation is an inherent characteristic of crystalline materials under long-term load, and needs to be controlled by increasing crystallinity, reducing stress, and selecting suitable materials.
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