Variation propagation modeling and analysis at preliminary design phase of multi-station assembly systems

Purpose - Dimensional variation management is a major challenge in multi-station sheet metal assembly processes involving complex products such as automotive body and aircraft fuselage assemblies. Very few studies have explored it at a preliminary design phase taking into consideration effects of part deformation on variation propagation, since early design phase involves the development of imprecise design models with scant or incomplete product and process knowledge. The objective of this paper is to present a variation model which can be built into the preliminary design phase taking into consideration all of the existing interactions between flexible parts and tools in multi-station sheet metal assembly process. Design/methodology/approach - The paper addresses this problem by first, presenting a beam-based product and process model which shares the same data structure of the B-Rep CAD models, and therefore can be embedded in CAD systems for automatic product skeletal design; second, determining the influence of part deformation, for various, differing joining and releasing schemes, on variation propagation; and third, utilizing this information to generate a vector-based variation propagation model for multistation sheet metal assemblies. Findings - This paper presents a beam-based product and process model which shares the same data structure of the B-Rep CAD models, and therefore can be embedded in CAD systems for automatic product skeletal design; determines the influence of part deformation, for various, differing joining and releasing schemes, on variation propagation; and utilizes this information to generate a vector-based variation propagation model for multistation sheet metal assemblies. Originality/value - A truck cab assembly is presented to demonstrate the advantages of the proposed model over the state-of-the-art approach used in industry for sheet metal assemblies.