Investigations on Forging Dies with Ceramic Inserts by means of Finite-Element-Analysis

The tools in hot forging processes are exposed to high thermal and mechanical loadings. Tempering of the tool edge layer occurs as a result of thermal loadings. This leads to a gradual hardness loss of the tool material and increase of wear over forging cycles. Hence, the tool life in hot forging is mainly limited by wear. An extension of the die service life can be achieved by the use of ceramic inserts. The integration of ceramics into the die base plate made of hot-work steel is realised by active brazing, whereby it possible to apply ceramic in region with high wear. It has to be ensured in the design process of ceramic inserts for forging dies that no critical tensile stresses occur in the ceramics. A reliable design of the ceramic inserts is possible only through consideration of brazing and forming process. The development of a Finite-Element-model for the design of forging dies with ceramic inserts is the intention of the work presented in this paper. At first the forging process with a conventional die is analyzed concerning abrasive die wear to identify regions with high wear risk applying a modified Archard model. Based on the results of wear calculation, a forging die with ceramic inserts is investigated in terms of joint stresses at the end of the active brazing process. Subsequently, the forging process considering the residual stresses caused by joining is simulated in order to obtain the die stress in use.