Multi-stage and robot assisted incremental sheet metal forming: a review of the state of art and comparison of available technologies

Incremental sheet metal forming is a recently innovated technology of achieving asymmetric sheet metal parts without using a die and through computer numerical control machine tool based path programming by inducing localized plastic deformation with a spherical ended tool. One of the major limitations of the existing method of incremental sheet metal forming is the limiting wall angle, where a wall angle of greater than about 70° is difficult to obtain. The recently proposed solution of multi-stage incremental forming can enable obtaining wall angles close to 90° but it takes longer manufacturing time and may pose problems for materials that severely strain harden. Robot-assisted incremental forming has a potential to offer an alternative solution for steel wall angle limitation but the existing work in the literature on robot-assisted incremental forming mostly focused only on the use of a standalone robotic manipulator instead of the limiting 3-axis CNC vertical machining center or a more expensive 5 or 6-axis vertical machining center. In this paper a review and comparative study of existing multi-stage incremental forming and robot-assisted incremental forming technologies in solving the limiting wall angle problem is presented.