Complex injection moulded components - Bridging the knowledge gap

Injection moulding is the predominant manufacturing process enabling the production of precise and consistent polymeric parts at a high volume. The final performance of those parts is critically dependent on their melt flow history and the current approach of testing simplified specimens produced by idealized melt flow conditions to specify new or enhanced materials is therefore not sufficient, since final parts often feature a more complex geometry. The purpose of this research is to highlight this omission by conducting high velocity impact and quasi-static tensile tests on PA-12 specimens obtained from a new concept injection moulding tool. This mould allows controlled modification of the material flow by adding specific mould tool design features which lead to the creation of a weld line, flow hesitation, or combination of both of these irregular flow phenomena and is therefore an improved representation of final injection moulded components. Furthermore, test specimens representing simplified as well as more complex geometries can be obtained from the same moulded samples, guaranteeing identical applied process conditions. The occurring microstructural differences due to the diverse melt flow history are verified using optical microscopy and Differential Scanning Calorimetry.