Experimental evidence on the twisting of incrementally formed polymer sheets by varying the toolpath strategy

Abstract. In recent years, polymer sheets have been formed by a relatively innovative technology, born for metals and in line with the layered manufacturing principle of rapid prototyping, the incremental sheet forming. This process guarantees high customization and cost-effectiveness but, at the same time, activates some peculiar defects like the twisting phenomenon. To reduce the risk of twisting and the occurrence of failures, it is preferable to reduce the forming forces and one of the solutions is the choice of opportune toolpath strategies. Concerning this, the present experimental research is along the same lines as recent numerical works of the authors; thermoplastic sheets were worked by incremental forming by varying the toolpath strategy. Following the realization of cone frusta, the forming forces and the deformation of the sheets were monitored, to investigate a toolpath strategy capable of reducing the risk of failures and defects for incrementally formed polymer sheets.