Abstract:
The development of additive manufacturing (AM) in the past decade has brought along with it a number of new opportunities and challenges when it comes to how parts are manufactured. While this development represents an increase in the capabilities and performance of the AM parts, much work and research still needs to be done in order to ascertain how to avoid the limitations that plague AM such as low dimensional accuracy, high surface roughness, and large tensile residual stress. Ongoing efforts to improve part quality through process optimization of parameters such as scan speed and laser power, post heat treatment, or machining, are currently being pursued to mitigate these limitations, and it is likely that the fabrication of a functional part lies within the use of all of these efforts. Little study has been done to characterize surface integrity of an as-SLM part followed by milling (e.g., hybrid SLM-milling). In this paper, surface integrity including surface roughness, microstructure, and microhardness have been characterized for the IN718 samples processed by the hybrid process. It has been found that surface integrity can be significantly improved by the hybrid SLM-milling route. To investigate the machinability of the deposited materials, energy consumption was collected and analyzed in terms of specific energy between dry and flood milling of as-SLM IN718, dry-milling of conventional IN718, and flood-milling of conventional IN718. Energy consumption was the lowest for both flood milling cases compared to the dry milling case, and the lowest for both as-SLM cases in comparison to the conventionally produced cases.
