Skin Model Shapes for multi-stage manufacturing in single-part production

Geometrical features are fundamental elements for the fulfilment of the functional product requirements. Therefore, their inevitable deviations caused by manufacturing inaccuracies are the main issues in the field of tolerance management. To close the gap between physical part description and nominal model representation, the framework of discrete geometrical representatives via Skin Model Shapes has been developed and continuously enhanced. As the underlying concepts are based on final virtual parts, consistent inferences to every single manufacturing step are not fully investigated in literature. This paper presents the development of Skin Model Shapes based on the virtual representation of intermediate part outcome (in-process geometry) and the integration of machining processes. Thus, integration and simulation of different kinds of deviations are enabled at each manufacturing stage considering error accumulation due to machine specific inaccuracies, such as tool movement and fixturing. Furthermore, the effect of inaccuracies on the final conformance result can be quantified at each manufacturing stage. A case study is presented to illustrate the entire approach and to demonstrate the validity of the proposed methods.