On forces, formability and geometrical error in metal incremental sheet forming

The present paper deals with incremental sheet forming (ISF), a metal forming process developed in the last 20 years. Main advantages characterising this technology are its high flexibility and the possibility of reducing development times and costs. ISF consists of a simple hemispherical tool, moved by a CNC machine or a robot, which locally deforms a metal sheet moving along a defined path. The desired part profile can be obtained using three ISF techniques: single point incremental forming (SPIF) and two points incremental forming (TPIF) with either negative or positive die. In this work, a part, whose geometry was chosen to be representative for sheet formability through ISF, was formed considering the different ISF techniques. Moreover, the influence on the produced part of the adopted tool path step depth increment was investigated. Experimental tests were conducted and the results were analysed in terms of forming forces, material formability, process accuracy and final part thickness.