Optimizing formability of incremental sheet forming using the straight groove test assessed with a variable wall angle conical frustum

The current study is focused on Robot Assisted Incremental Sheet Forming (RAISF) of AA 6061 alloys. A simple and streamlined approach is presented to optimize the forming parameters to maximize formability during RAISF; the forming parameters are the tool speed, the step depth, and the tool diameter. The optimized parameters are found using a Design of Experiments (DOE) methodology applied to a straight groove test. Straight groove tests were conducted on 39 samples chosen according to a Central Composite Response Surface Design (CCRSD) methodology. Formability is assessed by considering the groove depth, spring back, and forming time; the combination of tool speed ($84.65,\mathrm{mm}/s$), tool diameter ($12.5\mathrm{mm}$) and step depth ($0.4\mathrm{mm}$) were found optimal. A Variable Wall Angle Conical Frustum (VWACF) was then fabricated to assess the effect of the optimized parameters on the limiting conical wall angle. Finally, a conical frustum of constant wall angle ${60}^{\circ }$ was fabricated, and its forming limit compared with the conventional forming limit of AA 6061 obtained by a Nakajima test.