An approach to increasing the service lifetimes of nitrided dies for aluminium hot extrusion: A case study

摘要

In this investigation we studied the relationships between the design of dies for aluminium hot extrusion, the contact pressures on the die's bearing surface, the length of the bearing surface, the quality of the nitrided layer and the service lifetimes of the dies. Four nitrided dies for Al hot extrusion with a specific die design were selected to outline the approach for increasing their service lifetimes. The different die designs resulted in different contact-pressure distributions on the die's bearing surface and, consequently, in different service lifetimes. The relative values of the contact pressures, i.e., their higher or lower values with respect to the reference die, were assessed in terms of the observed wear patterns on the nitrided samples previously obtained during laboratory wear testing. The proposed approach makes it possible to optimize the geometry of the extrusion dies, which can, together with the optimization of other technological parameters, result in a prolongation of the service lifetimes of the dies. (C) 2017 Elsevier B.V. All rights reserved.