Mould filling analysis of aluminium extrusion dies

During trial pressings of an aluminium extrusion the shape of the first extrudate (nose piece) tells the correctors how to change the die geometry to obtain an acceptable product. In this paper the initial filling of an aluminium extrusion die is analyzed with the objective to predict the shape of the nose piece. The calculation domain is discretized using P1+P1 tetrahedral elements. The analysis is executed as an Eulerian analysis, where the material flows through the mesh. The whole domain is divided in an aluminium domain and an air domain, where the air is modeled as a pseudo material. The interface between the aluminium and the air is tracked by convection of the initial material coordinates. After the aluminium leaves the die, the free surface of the extrusion is calculated by an ALE method. The formulation of the element, the convection of the initial coordinates, the handling of the boundary conditions, the modeling of the air domain and the reconstruction of the free surface after extrusion are treated in this paper. The results of the simulations are compared to results of real extrusions.