Application of DFSS Taguchi Method to Design Robust Shock Tower

Design for Six Sigma (DFSS) is an essential tool and methodology for innovation projects to improve the product design/process and performance. This paper aims to present an application of the DFSS Taguchi Method for an automotive/vehicle component. High-Pressure Vacuum Assist Die Casting (HPVADC) technology is used to make Cast Aluminum Front Shock Tower. During the vehicle life, Shock Tower transfers the road high impact loads from the shock absorber to the body structure. Proving Ground (PG) and washout loads are often used to assess part strength, durability life and robustness. The initial design was not meeting the strength requirement for abusive washout loads. The project identified eight parameters (control factors) to study and to optimize the initial design. Simulation results confirmed that all eight selected control factors affect the part design and could be used to improve the Shock Tower's strength and performance. Non-dynamic analysis Smaller-the-Better (STB) was used for this project with the primary objective of reducing stress in part, which contributes to the higher durability life. The number of Simulation decks was generated using the L18 Orthogonal Array. Optimized front shock tower design met the strength requirement for 10% higher magnitude washout loads. The Optimum Design improved part robustness by 9.6 dB (actual) compared to the initial design. Key control factors that will enhance part strength are; shock tower material type, rib thickness, material addition at the rib/collar junction, spacer plate gauge/diameter and collar height. One of the project's objectives was to study the effect of several Shock Tower materials for this application, including HPDC alloys such as Aural-2, Silafont-36, Magsimal-59 and magnesium AM60B, which showed improvement in part strength and durability. Besides, the strength and ductility of AM60 material can be further improved by adopting the High-Pressure Supper Vacuum Die Casting process.