Manufactured part modeling for characterization of geometric variations of automotive spaceframe extrusions

This article presents a method for characterizing geometric shape variations in manufactured automotive spaceframe extrusions using measurement data obtained by a Coordinate Measurement Machine (CMM). With a manufacturing perspective, a modeling scheme is proposed for representing the actual shape of the extrusions. Systematic deviations in the geometry of the parts from their theoretically perfect design description models are described by the critical parameters of their manufactured part models (MPMs), which are constructed by fitting CMM data through an optimization. The manufactured part model can then be interpreted in a meaningful way for improving bending process as well as quantifying the process capability. An application of the methodology is illustrated through the analysis of experimental data for rotary draw bent extrusions used in the aluminum intensive automobiles.