Optimization of Single-Point Incremental Forming Process of ASTM A653 CS-A Steel Sheets Through Taguchi Methods

Incremental sheet forming (ISF) is a free forming process of parts in a specific equipment like CNC machining centers or special hexapod robots. It stands out for its high formability and low production cost, being ideal for prototypes and small batches. The main design parameters are the wall angle, material and sheet thickness and, most of the cases, they cannot be modified or even adjusted to improve the manufacturing performance. On the other hand, the main process parameters that impact the product total quality are tool rotation, vertical step size, lubrication and all of them can be continuously optimized. Thus, these last three process parameters are widely investigated in several kinds of research. This paper investigates the effects of applying different tool rotation when shaping a truncated cone of ASTM A653 CS-A steel sheets − 0.43mm thick - with different types of lubrication and vertical step size. It was chosen three level for each factor: 600, 1200 and 1800rpm for tool rotation n; 0.6, 0.8 and 1.0mm for vertical step size Δz and dry, mineral oil and molybdenum disulfide grease for lubrication condition. The statistic Taguchi method was applied to evaluate and optimize the maximum depth of forming and better surface quality (roughness Ra and Rz). The results confirmed the use of mineral oil as the most predominant factor in the process for minimum roughness, maximum forming height, and minimum deformation levels. Hence, the best set of parameters was 600rpm, 0.6mm vertical step size and mineral oil as a lubricant. The parts tested did not show any defects. Additionally, it was verified that the increase of the tool rotation negatively impacts the ISF formability in the case of a thin specimen due to the increment of temperature.