Finite element analysis of multi-hole extrusion of aluminum-alloy tubes

The multi-hole extrusion of aluminum-alloy tubes was examined in the present study using both the finite element analysis and the experimental approach. The finite element analysis was first validated qualitatively and quantitatively by the experimental data obtained from the single-hole extrusion process. The effects of the process parameters, such as extrusion temperature, extrusion speed, dimensions of billet, and location of holes on the extrusion load and the shape of extruded tubes were then studied by the finite element analysis. The finite element analysis reveals that the most crucial process parameter is the number of holes and their locations on the extrusion die. It is also found that a uniform deformation of mandrel and a balanced flow at the exit of extrusion die could be achieved if the position of holes is near the centroid of the die area. An expression of the eccentricity of the holes was defined by a ratio. An eccentricity ratio that represents an optimum position of the holes was then developed for the two-hole extrusion of aluminum-alloy tubes to avoid any bending or curvature of the extruded product. The developed approach could be also extended to other multi-hole extrusion of more than two tubes and help the die engineer to design a more productive extrusion process.