Fixture Design Methodology for Sheet Metal Assembly Using Computer Simulations

Sheet metal assembly is a common manufacturing process for several products such as automobiles and airplanes. Since all manufacturing processes are affected by variation, the key characteristics or critical dimensions may not be nominal. This paper presents a new fixture design methodology for early evaluation of sheet metal assemblies. Fixture design has been extensively studied for machining processes. Unfortunately, little investigation has been done for sheet metal assembly processes considering the effect of fixture layout on the assembly dimensional variation. The new fixture design methodology is based on classifying the assemblies into three categories depending on the stiffness of the assembly components: rigid-rigid, compliant-rigid and compliant-compliant assembly. Finite Element Analysis (FEA) and design of computer experiments have been used to derive response models for sheet metal assembly applications. The response models are used to analyze the final assembly sensitivity to fixture, part and tooling variation for different assembly configurations. Based on these results several design guidelines are proposed for fixture design on sheet metal assembly.