Added Value in Tooling for Sheet Metal Forming through Additive Manufacturing

Additive manufacturing for tooling applications has seen a new boost with emergence of Laser Beam Melting, a technology being capable of layer manufacturing completely dense parts and tool inserts in standard high-alloyed tool steel. Moulding applications have been the first in making use of the advantageous conformal cooling, e. g. in plastic injection moulding and aluminium high pressure die casting. Forming dies as another potential application for layer manufactured tooling have been scarcely addressed so far, e. g. in die forging. The potential of additive manufacturing for added value in tooling applications has now been investigated for sheet metal forming processes. The paper presents results of a research project to apply laser beam melting to manufacture tooling for the hot sheet metal forming process of press hardening. The paper describes the shortcomings of current cooling channels in press hardening tools and the resulting waste of energy and inadequate cooling effect in critical areas. The paper shows how an innovative cooling system has been implemented in the die through laser beam melted die inserts. Cooling of specific die areas has been realized by placing specially designed cooling channels very close to the die cavity, targeting shorter cycle times, improved mechanical properties of press hardened parts manufactured in the die and a reduction of energy consumption for cooling and idle times of forming presses. The paper will present the achieved results. Further application examples from other forming processes like deep drawing of thick metal sheets and die forging will also be presented.