Impact of wire and arc additively manufactured workpiece geometry on the milling process

In recent years, the wire and arc additive manufacturing (WAAM) process has been given attention as a possibility to save material during the production of large-scale parts. Drawbacks of the WAAM process are the relatively low surface quality and the low form accuracies, which require post-processing of all functional surfaces. The milling process is researched as a post-processing option, especially to achieve high form accuracies. While several authors presented successful applications of the milling process, the difficulties of machining wire and arc manufactured parts (WAAM-parts) due to the part geometry have not yet been researched. In the present research, the impact of the WAAM-part geometry on the milling process was analyzed by machining three sets of samples, and guidelines for a milling strategy were developed. The results show that the geometry leads to modulated cutting forces, whose frequency, in turn, has to be considered for the milling setup. Additionally, the modulated cutting force leads to a periodically changing deflection resulting in a form deviation on the final workpiece.