Parametric effect analysis of free-form shape error during sheet metal forming

Compliant sheet metal parts or free-form shaped parts are widely used for automotive bodies, aerospace fuselage/wing or home appliances. Intrinsic flexibility of sheet metal along with forming process variability throws a number of challenges to produce geometrically conforming parts. Additionally, emerging optical non-contact metrology scanners offer to capture entire part geometric quality information which enables virtual design and manufacturing at early stage. This paper focuses on developing a generic functional data analysis based approach to quantify geometric error/shape error which are generated by process or material parameters (such as material thickness, stamping speed and blank holding force) during sheet metal forming process. The research methodology involves:(i) experimental investigation by varying the design parameters;(ii) capturing entire surface based shape error information (ie high density cloud-of-points, CoPs) by using optical scanner;(iii) functional mapping of shape error to design parameters (responsible to generate the data) by using deviation field decomposition approach; and (iv) parametric analysis of process parameters by developing analytical surrogate model. The proposed approach concentrates on finding root causes of failure, usually unforeseen if only based on heuristic approaches. The applicability and effectiveness of the proposed methodology have been illustrated with industrial case study.