Steady state thermal model for the hot chamber injection system in the pressure die casting process

This paper describes a three-dimensional numerical model that is used to predict the steady state thermal behaviour of the metal injection system of a hot chamber pressure die casting machine. The behaviour of the injection system is considered in conjunction with that of the die. The boundary element method (BEM) is employed, as surface temperatures are of primary importance. The model yields time-averaged injection system and die temperatures and the heat input from localised heating arrangements (injection system). This is valuable information that can be used in the optimisation of the process. The die model utilised is based on that presented by Davey and Hinduja (Int. J. Numer. Methods Eng. 30 (1990) 1275-1299). A number of novel techniques that improve the efficiency and performance of this model are presented. An efficient scheme is presented for modelling the flow of heat through the melt. A procedure is developed to account for the thermal effects of flow in the nozzle, gate and runner regions. An iterative procedure is developed that enables the average amount of energy supplied per cycle by the heater band, to be calculated. The coupled injection system-die model is verified using thermal data obtained from experimental work. The predicted and the measured temperatures are shown to be in good agreement. Based on the numerical predictions and the experimental data obtained, recommendations are made for improving the thermal behaviour of the existing hot chamber injection system and the die used in the experimental tests.