The heat transfer during filling of a high-pressure die-casting shot sleeve

Microstructures in high-pressure die-cast products (HPDC) are important for the mechanical properties. During filling of the shot sleeve, the liquid metal dissipates superheat and solidification starts. The solidification may result in externally solidified crystals (ESCs) or cold flakes in the product [H.I. Laukli, L. Arnberg, O. Lohne, Int. J. Cast Metals Res. 18 (2005) 65-72]. The temperature of the melt in the shot sleeve is influenced by several parameters, such as liquid metal superheat, the heat transfer coefficient (HTC), surface properties of the shot sleeve and alloy composition. In order to get a better quantitative understanding of the heat loss during filling, investigations of the temperature history in both liquid metal and the shot sleeve wall have been carried out. A replica of an industrial shot sleeve was made and filling experiments were carried out. Thermocouples at different locations and depths in the melt and steel cylinder were used to measure the temperatures. The thermal field in the shot sleeve was also modelled using the simulation software MAGMASOFT®. The results from the casting experiments and casting simulations were compared to estimate the heat transfer coefficient.