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The main objective of this paper is to demonstrate how flow and solidification simulation were used in the development of a new gating system design for three different magnesium alloys; and to determine the relative castability of each alloy based on casting trials. Prototype tooling for an existing 3-slide rear wheel drive automatic transmission case designed for aluminum A380 was provided by General Motors. Flow and solidification simulation were performed using Magmasoft on the existing runner system design using A380 (baseline), AE44, MRI153M and MRI230D. Based on the filling results, new designs were developed at Meridian for the magnesium alloys. Subsequent modeling was performed to verify the new design and the changes were incorporated into the prototype tool. Casting trials were conducted with the three magnesium alloys and the relative castability was evaluated.

The robustness of large magnesium thin wall die castings has been proven through testing performed directly on components and supported by statistical analysis of the test data. In addition, an extensive investigation carried out on specimens cut from components tends to show that the material exhibits a composite failure mode. The skin shows high consistent elongations close to the intrinsic potential of the alloy, while the core properties vary with the micro-defects inherent to the process. Design data has therefore been developed by reverse engineering from component tests, considering local properties and loading mode.