Influence of material properties on spontaneous buckling of thin-walled injection molded parts
[ 1 ] Instytut Technologii Materiałów, Wydział Budowy Maszyn i Zarządzania, Politechnika Poznańska | [ D ] phd student | [ P ] employee
chapter in monograph / paper
EN Injection molding technology is widely used for manufacturing of thin-walled parts (such as covers and packaging). In those applications minimizing of wall thickness is crucial to improve the economical aspects of production. Along with thinwalls, high injection and packing pressure must be used to obtain good parts quality. After the injection molding process, the residual stress presence leads to the part shrinkage (reduction of dimensions). With compressive nature of residual stresses and its relatively high magnitude (in comparison to part stiffness) the buckling phenomenon should be considered during the design stage of the part. Buckling is characterized by the sudden out-of-plane deflection of the part (well-known example of this instability is compressed ruler that bends when too high axial load is applied). This phenomenon can be present in thin walled parts with high length-to-thickness ratio and low area moment of inertia. During the packing phase of injection molding process compressive stresses builds up in the part, so spontaneous buckling can occur. In this research the relation between material properties of the polymer and part stability was investigated. Several different thicknesses and geometries were investigated to obtain information about minimal wall thickness values that should be used to avoid the buckling occurrence.
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