Abstract. Bending in sheet metal forming is defined as uniformly straining process around a linear axis. A V-bending process is normally used in sheet metal working due to the tool and process simplicity. The main problem in bending process is a springback occurrence which causes an error in part dimension. In a micro level, the springback angle is difficult to be assessed because of the influence of size effects in all aspects of the system. The springback behavior has been investigated in many previous kinds of research. However, the springback correction is still needed to be studied extensively so that it can be implemented reliably in micro-bending. The purpose of this research is to investigate the influence of punch velocity and holding time to the springback angle. The process is performed to the 0.1 mm thickness of copper foil. The punch velocities are 0.1 mm/s, 1 mm/s, and 10 mm/s. While the variation of holding time, which is set during the bottoming stage, are 7 s, 9 s, and 11 s. The result shows that the punch velocity clearly influences the springback angle. In addition, the holding time during the bottoming stage is a potential factor in springback angle correction.

Sheet metal bending is defined as a straining process of flat strip material around a linear axis. The micro V-bending process was conducted to investigate its punch force behavior with 0.1 mm thick copper foil. The V-shaped configuration of the punch and die provides a simplicity of tools and an ability to produce different bending angles with a single tool. During the straining of material, a unique force profile, which is related to punch trajectory, occurs. The process was performed with the punch speeds 0.5 mm/s, 1.0 mm/s, 5.0 mm/s and 10.0 mm/s. The results showed that the punch force profile consists of the free-bending stage and the coin-bending stage. In the free-bending stage, the force magnitude was not influenced by the punch speed for the same geometrical and mechanical properties of the sheet material. Furthermore, during the coin-bending stage, the force magnitude increased significantly since the material needed to be bottomed.

A die clearance is the main factor that influence a proportion of a shear edge. With a larger die clearance, the shear edge will be more irregular. A good blanking quality has a shear edge with a large portion of shear zone, i.e. a smooth and shiny area, and small portions for the rest. In this research, the investigation was held to study about the shear edge occurrence on micro-blanked-part with a specified die clearance and a varying punch velocities. The investigations of the shear edge in micro level provide more distinct difficulties comparing with the macro level due to the restricted size of micro-part. The experiment applied 0.5 mm/s and 5 mm/s of punch velocities in blanking of aluminum and copper foil with 0.1 mm thickness. The die clearance was determined at 0.033 mm. The material foils were set at longitudinal and transverse direction to observe the influence of the rolling direction to the shear edge proportion. The result showed that with a higher punch velocity, the shear zone portion became larger. It is concluded that with the specified die clearance, the shear edge quality can be improved if higher punch velocity was applied.  Index Terms-shear edge, punch velocity, micro-blanking process 279

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