Advancements in robot-assisted incremental sheet hydroforming: a comparative analysis of formability, mechanical properties, and surface finish for rhomboidal and conical frustums

Incremental sheet forming (ISF) is a highly versatile and flexible process for small batch production of complex sheet metal parts. Since, there is no die used in the process, the accuracy of the parts formed is an area of concern in ISF. In the current work, an experimental set-up was developed for robot assisted incremental sheet hydroforming (RAISHF) and was conducted on AA3105 to fabricate different shapes. Formability by RAISHF was found to be better than robot assisted incremental sheet forming (RAISF) due to fluid pressure from the back of the sheet which can be impart more ductility to the sheet. Additionally, a more uniform thickness was achieved by the RAISHF. A variable wall angle conical frustum (VWACF) was fabricated by each process and their formability was compared. The maximum wall angle before the onset of fracture was 73° and 64° by the process of RAISHF and RAISF, respectively. Also the thickness along the length of the cone was more uniform by RAISHF than RAISF. Further, the effect of curvature on mechanical properties and surface finish of the formed product by RAISHF was examined by fabricating a rhomboidal and conical frustums of a fixed wall angle of 45°. Tensile test and surface finish test were conducted on the samples taken from the two types of frustums. Mechanical properties and surface finish were found better of the rhomboidal frustum due to flat wall.