Mechanical Benefits of Gas Assisted Injection Moulding Application in Design of Structural Parts

Abstract

Due to of many advantages and specific properties plastics are gradually becoming the most widely used materials in the engineering industry. In the last years, more and more metal parts are converted to plastic, in the cases of mechanically loaded parts as well. However, the usage of plastic is limited by its mechanical properties and production possibilities. Conventional injection moulding as the most productive plastic part production technology mostly enables the manufacturing of thin-wall parts with uniform wall thickness, what restricts full-fledged utilization of plastics. In this study, the benefits of progressive gas assisted injection moulding is investigated in order to produce plastic parts with higher mechanical properties. The paper presents complex study with respect to structures generated in material during gas penetration state, orientation of reinforced short fibres, stress relaxation behaviour, notch effect of rough gas channel surface, producible cross-section profiles with high moment of inertia and undesirable production effects, which can occur during gas aided moulding technologies. Finally, the mechanical properties of specimen produced by conventional and gas-assisted injection moulding were compared using numerical analyses. For comparison, integration of two numerical solver - FVM for fluid analysis of plastic/gas injection and FEM for structural analysis of specimen strength/stiffness were used.