The Forming Limit Diagram (FLD) is a criterion used to assess the formability of sheet metal during a manufacturing process. Traditionally, FLDs are obtained through manual measurements using Mylar tape or through the use of automatic deformation measurement systems such as ARMIS and ARGUS. However, the use of Mylar tape is not user-friendly and can result in errors. Additionally, the cost of using automatic measuring equipment is high. To address these challenges, we propose a method that utilizes a low-cost USB digital microscope and the Python-based open-source library, OpenCV, to obtain forming limit diagrams. This approach allows for the measurement of deformation on specimens by analyzing circles printed on them. To evaluate the performance of this method, a circular grid was printed on a sus430 0.3 t specimen and a nakajima test was conducted. The strain data obtained using this system was then compared to the FLD obtained with the ARGUS system. The results confirmed that the formability of sheet metal can be assessed at a lower cost using our proposed method.

The incremental sheet forming (ISF) process is a method of forming a metal sheet with a machine tool, such as a CNC or robot arm. In this study, the surface characteristics of the ISF process using the ball type tool and the conventional hemispherical tool were analyzed. Comparative experiments were conducted with the same size of the hemispherical tool and ball type tool. In experiments, the tool feed rate and spindle were fixed, and the step down was set up with seven levels. The surface profiles and roughness such as R_a and R_z after the ISF process with different values of the step down were compared. Additionally, the surface morphologies were analyzed through the scanning electron microscope. A ball type tool which can move and roll, can reduce the effect of friction effectively. As a result, the ISF process with a ball type tool can greatly reduce the damage of the surface of the product.