Lightweighting technologies: Analyzing strategic and economic implications of advanced manufacturing processes

Abstract

High-pressure die-casting (HPDC) is a proven manufacturing technology to cast aluminum and magnesium alloys. Transportation industries are under increased pressure to reduce the mass of cast parts in order to cut fuel use and CO2 emissions, and increase load. Reducing mass and improving mechanical properties with current HPDC is not practical due to processing limitations that result from air entrapped during metal filling as well as limitations on performing additional processes such as heat treatment that can expose the porosity or voids. Super vacuum die-casting (SVDC) is an innovation that aims to overcome this challenge by introducing a vacuum to draw air from the die cavity before filling. While there is a significant literature on the technical performance of vacuum assisted technology, the authors are unaware of previous work focused in analyzing short- and long-term cost-benefit tradeoffs. This manuscript's goal is to evaluate the strategic and economical implications of novel SVDC technology as well as its upstream and downstream processes, however, the cost implications of use-life and end-of-life is not considered in this study. To do this, we develop and describe an analytical model to map future scenarios, both production and product, to expected production cost difference between SVDC and conventional die-casting. Using these models we find that materials and die casting process costs dominated the cost in both HPDC and SVDC. From analysis of several case studies, these dominant costs translate directly into the strategic advantages and disadvantages of SVDC. SVDC can provide cost savings if a part can be redesigned to reduce mass. Some of that cost savings is lost, however, due to added heat treatment costs and added tooling and system costs. The effect means that SVDC can reduce cost particularly for larger parts and when production volumes are higher. The cost advantage of SVDC is strongly dependent on production volume, and realized mass savings. From a variance-based sensitivity analysis, it can be seen that at higher production volumes (around 100k per year or more) breakeven requires a mass savings of 15% for small parts and around 12.5% for medium and large parts. However, when production volumes are low (say around 5000 parts per year) these values rise to 45%, 35%, and 30%, respectively.