Analysis and optimization of zinc alloys die casting process

Process optimization to improve quality of parts, to enhance production times and, consequently, to reduce costs, is a crucial element in manufacturing companies. The aim of this Thesis, result of my five months internship at the Quality department of Dynacast Italia Torino S.p.A. in Grosso (TO), is to introduce efficient improvement actions to the current hot chamber die casting process of zinc components. For this purpose, it is first necessary to provide a general introduction to zamak alloys, offering an overview of their composition, mechanical properties and influence of alloying elements, outlining also the basic functioning principles of hot chamber die casting machines which, combined with the versatility of zinc alloys, allow the reaching of high quality performances within advantageous times and costs. After a detailed casting defects analysis, considering all the possible formation causes and potential negative effects on the final product (reduced strength, aesthetic or functional problems), researches performed in Dynacast, during the internship experience, have demonstrated that continuous quality improvement studies are necessary to define efficient action plans to prevent defects occurrence; for this scope, the thesis work reports practical implemented corrections resulted in tangible quality benefits, reducing waste during production and ensuring saving costs. Ishikawa diagram represents the tool used during the internship to detect potential causes of a problem, in order to perform quality defect prevention. At this point, the thesis work focuses on the importance of introducing automated technology in the production process and simulation software in the Research and Development activity as well as on the necessity of setting adjustments on the basic casting parameters. The enhancement of the melt injection phase, resulted from the optimization of parameters like nozzle temperatures, specific casting pressures and die temperatures, in fact, can determine a consistent improvement of the production final quality, reducing scrap parts. All these considerations, as this work aims to demonstrate, are the evidence of the importance of ever-increasing process improvements in order to allow Zinc alloys die casting industry to have a competitive advantage in the market, especially in the automotive field, thanks to the benefits that casting components produced with this technology can offer.