Toolpath strategy for evaluating the coefficient of friction in the incremental sheet forming process

Owing to its inherent flexibility, low tooling costs, and enhanced formability, incremental sheet forming is particularly suitable for the rapid manufacturing of high-value-added, small-batch, and customized complex sheet components. However, the tribological conditions at the tool/sheet interface play a crucial role in governing material deformation. The presence of highly localized contact pressures adds significant complexity to the interpretation and modelling of frictional behaviour within the process. The aim of the present study is to evaluate the coefficient of friction between the forming tool and the sheet in the incremental sheet forming process. To this end, a flat-head forming tool is employed, and a dedicated toolpath is developed. The parameter under investigation is measured through an in-depth understanding of the typical issues affecting incrementally formed components and a careful interpretation of the forming force signals. Finite element analyses support the results from the experimental campaign.