Injection Molding
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Large Creep Deformation of Block Copolymer Polypropylene Injection Molded Products
Problembeschreibung
The product slowly deforms 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.
Ursachenanalyse
（1）The crystallinity of block copolymer polypropylene is low, and the molecular chains easily 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 approaching 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 allowance
Lösung
（1）Increase the mold temperature to a higher value within the 40-90°C range to increase the crystallinity
（2）Increase the product wall thickness or reinforcing ribs to reduce the service stress level
（3）Control the use temperature within the long-term temperature resistance range of the material
（4）Select a high-molecular-weight grade or add reinforcing materials to improve creep resistance
（5）Consider the creep allowance in product design, leaving creep deformation in the initial dimensions
Wichtigste Erkenntnis
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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