The Application of Magnesium Die Casting to Vehicle Closures

During the last decade, advances in magnesium die casting technology have enabled the production of large lightweight thin walled die castings that offer new approaches for low investment body construction techniques. As a result, many OEMs have expressed an interest in magnesium door closure systems due to investment reduction opportunities, coupled with potential weight savings of up to 50%. However, for such applications, product engineers are faced with the challenge of designing for stiffness and strength in crash critical applications with a material of lower modulus and ductility compared to wrought sheet product. Concept designs for side door systems have been presented in the literature, and indicate that structural performance targets can be achieved. However, to date, series production designs feature a multitude of supplementary sheet metal reinforcements, attached to die castings, to handle structural loads. While this approach can still offer performance benefits, the additional cost of tooling and assembly has a negative impact on both overall weight and the business rationale. On the contrary, the magnesium door concepts presented in this paper describe the development of side door systems designed to replace the bulk of sheet metal stampings by a single magnesium die casting. A summary of the design, analysis, prototyping and testing stages is reported, in addition to the development of a series production door system for a 2004 model year vehicle. A review of manufacturing and test results demonstrate how magnesium can be used effectively in the manufacture of low investment, lightweight vehicle closures.