Correlation between process, microstructure and properties in high pressure die casting aluminium-silicon alloys

Nowadays automotive industry and, in general, transportation one increasingly needs light components in order to reduce total weights and therefore limit harmful emissions and fuel consumption. The die casting process, on one hand, is a versatile and highly productive process but, on the other, the elevated amount of defects found in the castings sometimes compromises the characteristics of the final product. This paper presents the results of the analyses carried out using a Reference Die, referred to as horse shoe-shaped die, specifically designed to generate as many kinds of defects as possible, at different levels of severity. A Design of Experiments method has been applied for analysing the influence of the main process parameters on the casting quality and an innovative sensor network installed on the machine allowed a continuous control of the process itself. Visual inspection, X-ray investigations and micrograph analyses have been carried out in order to assess the casting quality. Correlations between process parameters and casting quality have been deduced analysing the data collected through the equipment installed on the die casting machine: in-cavity sensor network, plunger speed and displacement sensors. Results show the effectiveness of the horse shoe-shaped casting in highlighting the correlations between process and quality and the strong influence of second phase plunger velocity, temperature and pressure on defect formation.