Advancements in the manufacturing of dies for hot aluminum extrusion with conformal cooling channels

Abstract

To prevent an overheating of the workpiece material and to increase the productivity in hot aluminum extrusion, the application of extrusion dies with conformal cooling channels manufactured additively by selective laser melting is known. Since, to date, the additive manufacturing processes are often accompanied with higher manufacturing time and costs in comparison to conventional subtractive methods, a new concept for a hybrid extrusion die is presented. Here, the large volume but geometrically simple die part, the die bridge, is manufactured conventionally by subtractive methods, and the smaller part with geometrical complexity, the tip of the mandrel, is built-up on it additively by laser melting. A further novelty of the developed die is the isolated feeding of the coolant up to the target area, close to die bearings, where the cooling shall be localized. Numerical and experimental investigations revealed that the profile’s exit temperature can be reduced locally and controlled which leads only to a moderate increase of the extrusion force. The experimental results show that the hybrid tools withstand the high mechanical and thermal loads which occur during hot aluminum extrusion.