Cutting Force in Peripheral Milling of Additively Manufactured Maraging Steel

Abstract

Additively manufactured parts have recently been applied to products in aerospace, automobile, and tool industries in terms of design flexibility and material consumption with mechanical strength. Because the surfaces of additively manufactured parts are coarse, milling is conducted as a post-process to achieve fine surfaces within the specified tolerance. However, the microstructures and the mechanical properties of additively manufactured metals differ from those of wrought metals. Therefore, the cutting characteristics should be understood to determine the appropriate cutting parameters. The paper studies the cutting process in peripheral milling of additively manufactured maraging steel in a cutting model. The cutting force, the surface finish, the chip morphology, and the tool wear were evaluated through cutting tests. Although the hardness of the additively manufactured workpiece was higher than that of the wrought workpiece, the maximum cutting forces were approximately the same. An energy-based force model was applied to discuss the cutting force characteristics in terms of the shear area and the shear stress on the shear plane. In milling of additively manufactured workpiece, the shear stress on the shear plane becomes larger than that of the wrought workpiece. However, the shear plane length is short at a large shear angle. Therefore, the cutting force does not significantly increase. The typical change in the cutting force of the additively manufactured workpiece is also compared with that of the wrought workpiece in terms of the cutting model. The chip flow directions, then, are analyzed in the cutting force model. The chips of the additively manufactured workpiece flow more in the radial direction than those of the wrought workpiece.