A digital twin approach to predict and compensate distortion in a High Pressure Die Casting (HPDC) process chain

Abstract

The HPDC industry is changing, and E-mobility is one reason for this – power train components traditionally produced by HPDC are eliminated as the industry abolishes internal combustion engines (ICE). The casting industry reacts to this challenge by extending its product range towards structural automotive components - essentially large area/low thickness geometries prone to distortion as result of inhomogeneous cooling and similar effects. As corrective actions like mechanical alignment are costly, alternatives are required which can either eliminate or compensate effects promoting distortion. The alternative proposed here is based on analysis of the full HPDC process chain and identification of the main process steps that control distortion, allowing a correct prediction of distortion throughout the processing sequence via a “digital twin” approach. Components considered are assumed to undergo a solution heat treatment after casting, followed by quenching and precipitation hardening. As the subsequent quenching bears a potential for introducing distortion similar to solidification and cooling after casting, this step is selected to deliberately introduce inhomogeneous cooling designed to counteract the residual stresses and distortion brought in during the preceding process steps. Knowledge of the exact state of the casting immediately before quenching as provided by the “digital twin” approach for each individual part provides the basis for deriving a suitable distribution of heat extraction rates over the part surface. The present study presents and discusses the basic strategies on the level of part series and individual parts as well as aspects of their practical implementation via adaptive spray cooling systems. The task is complicated by the high thermal conductivity of the aluminum alloys studied and the need to arrive, after quenching, at microstructures supporting the required levels of strength after the final warm aging step, i.e. supersaturated solid solutions of the alloy-specific precipitate-forming chemical elements. The viability of the general concept is demonstrated based on initial numerical modeling and simulation of a component cooled under varied thermal conditions, highlighting the distortion and distortion compensation potential.