Thermal Factors of Die Casting and Their Impact on the Service Life of Moulds and the Quality of Castings

Abstract

This article deals with the analysis of the temperature factors of die casting and the conditions of the service life of moulds. It also describes a mechanism of the origin of internal structures and development of crystallisation grains of aluminium castings depending on the degree of undercooling. The monitored factors are very important in terms of production efficiency and the quality of the casting, which is positively reflected in the most important economic indicators of the production. In die casting, the melted metal is pressed under high temperature into a mould cavity of significantly lower temperature. The mould is then exposed to thermal strain of individual surface layers of the mould material. The speed of cooling of the castings in the metal mould increases, causing an increase of thermal gradients in the casting. Intensive heat exchange between the casting and the metal mould has a negative effect on fluidity, which increases the danger of incomplete replenishment and the occurrence of cold joints.