Cut surface characteristics of aluminum alloy sheet in cryogenic shearing process

Abstract

Die cutting is a well-known process of sheet metal forming for separating sheet metal into the required shape. Compared with other cutting processes such as machining, this process has the advantages of a high production rate and low production cost. Currently, as a necessary process in sheet metal manufacturing, this process has been researched to improve the efficiency of the process and quality of cut components. In this study, the application of cryogenics in the die-cutting process was investigated, and the characteristics of the cut surfaces were examined. The shearing process was investigated using a die-cutting model. An aluminum alloy grade A5083 (JIS standard) was used as the workpiece. After shearing, the physical characteristics of the cut surfaces were examined using a 3-D laser scanner. Shear forces were also reported. The grain evolution in the shearing zone was also investigated. The results revealed that compared with the shearing process at room temperature, the ratio of clean cut to workpiece thickness was slightly increased. However, they showed differences in fracture characteristics. A concave feature in the fracture zone was generated at the cryogenic temperature, particularly for small clearances. These results were clearly explained based on the initial fracture angle and its propagation, and grain evolution. Based on the changes in the material properties at cryogenic temperatures, an elongated grain structure was easily generated, resulting in a larger initial fracture compared with that of the shearing process at room temperature. This is important when using the cut component, as the strength of the cut part decreases owing to the larger concave features. In addition, it provides helpful information on cut components that may require additional operations.