A Method Using FEA for the Evaluation of Tooling and Process Requirements to Meet Dimensional Objectives

Dimensional Engineering concentrates effort in the early design phases to meet the dimensional build objectives in automotive production. Design optimization tools include tolerance stack up, datum optimization, datum coordination, dimensional control plans, and measurement plans. These tools are typically based on the assumption that parts are rigid and tooling dimensions are perfect. These assumptions are not necessarily true in automotive assemblies of compliant sheet metal parts on high volume assembly lines. To address this issue, Finite Element Analysis (FEA) has been increasingly used to predict the behavior of imperfect and deformable parts in non-nominal tooling. This paper demonstrates an application of this approach. The complete analysis is divided into three phases. The first phase is a nominal design gravity analysis to validate the nominal design and tooling. In the second phase, the worst case scenarios are considered based on the previous programs to see their effects on assembly. Lastly, dimensional deviations and tooling loads are estimated to determine if they meet the constraints of both the part design and the tooling design. The novelty of this approach lies in the evaluation of the tooling requirements as well as the product requirements. The work is significant because it confirmed acceptable results from a process sequence that saved space and cost.