Fundamental investigations on the machinability of additively manufactured multi-materials

Additively manufactured multi-materials promise unique combinations of different material properties. However, the machining behavior of these materials is widely unknown. In this study, fundamental investigations on chip formation and morphology, cutting force, workpiece temperature after cutting and surface quality were conducted in orthogonal cutting experiments. Additively manufactured test specimens made out of 316L stainless steel processed by Laser Powder Bed Fusion (LPBF), and the nickel-based alloy Inconel 718 processed by wire-based Laser Metal Deposition (LMD-w) were machined. Investigations were conducted with single-and multi-material combinations as well as porous 316L material. Besides, conventional cast material was machined in order to draw a relative comparison. The results showed significant changes in chip formation and cutting forces between cast and additively manufactured materials, especially for Inconel 718. These differences can be attributed to the changed microstructure and material properties. For two-component multi-materials, the connection area between the materials acted as a defect only to a limited extent. It was shown that the main influence evoke from the cutting direction in relation to the build-up direction of the specimen.