Fracture-free cut surface characteristics of aluminum alloy sheet (AA5083-H112) using cryogenic press-shaving process

Abstract

Of late, aluminum alloy sheets are being increasingly used in the fabrication of automotive, marine, and aircraft parts. Typically, a metal-forming process is used to produce these parts. However, the fracture-free cut surface characteristics of these parts are still limited by the die cutting process, and a secondary operation, such as machining, is needed to overcome this limitation. In this study, the use of cryogenic temperatures in press shaving was investigated. In the shearing operation, the cryogenic temperature influenced the ratios of the die-roll, smooth-surface, and fracture-to-material thickness, particularly for the fracture texture. Applying cryogenics in the shearing process increased the smoothness of the surface by approximately 50%, and the concave feature formed on the sheared workpiece was approximately 45% deep. Additionally, the hardness under cryogenic-temperature condition was approximately 15% higher than that at room temperature. However, the shearing force increased by approximately 30%. With the shaving operation, the volume of the shaving allowance was reduced owing to the deeper concave features. This resulted in a downward movement of the shaving allowance during the shaving operation, allowing easier sliding along the punch face and easier bending underneath the punch face. Consequently, tearing could be prevented, and the shearing phase of the shaving operation could be delayed. The results revealed that compared with the conventional press-shaving process, in which tearing and fracture of approximately 0.393 mm were generated, the application of cryogenic temperature to the press-shaving process delayed the tearing and prevented fracture, thereby achieving a fracture-free cut surface characteristic.