Experimental and Finite Element Investigation of Hot Gas Forming Process of A6063-AZ80 Bi-layered Composite Tubes using Taguchi Methods for Design of Experiments

Given the demand for high strength, light materials in today's industry, fabrication methods implemented for manufacturing parts have become increasingly important. Hot Metal Gas Forming (HMGF) is a novel process that enhances the strength of the parts, while reducing total weight and fabrication time, due to the elimination of auxiliary processes such as welding. High temperatures are not feasible in hydroforming given the presence of water/oil in the forming process; however, there is no temperature limit in HMGF as the working fluid is gas. Drawing on Taguchi methods of experimental design, first, the axial feed and the internal pressure were evaluated at different temperatures (350, 400, 450 °C) and at three levels in terms of lowest thinning. The evaluation was performed through finite element simulation and the resulting optimum conditions were experimentally applied in bulge forming of a double-walled composite Al6063-AZ80 tube. The results of Taguchi methods and finite element simulation show that bulge forming of the tube at 400 °C with an internal pressure of 55 bar and axial feed of 4 mm is optimal for the HMGF process. Experiments were successfully performed under these conditions and showed good agreement with simulation results with a maximum difference of 5.49% in thickness reduction compared to simulations.