Effect of additive and subtractive sequence on the distortion of cone-shaped part during hybrid direct energy deposition

Abstract

Hybrid manufacturing combines additive manufacturing (AM) and subtractive manufacturing processes to achieve simultaneous benefits. Unlike traditional AM, it allows for interleaved subtractive steps, enhancing machining tool access for parts with high aspect ratios. However, optimizing the printing sequence remains as an area of exploration. In this study with two conical shapes, one exhibited a geometrical mismatch at the interface between two printing sections, while the other did not. 3D laser scanning, finite element simulation, and methodical analysis were used to understand this issue. Printing support structure before machining improved dimensional accuracy, with 0.5 mm reduction in distortion achieved, corresponding to 50 % of the final wall thickness. However, the absence of a feedback mechanism to track wall distortion after the additive process resulted in non-uniform wall thickness with a constant depth of cut during the machining operation. This research highlights the importance of process sequencing in hybrid manufacturing for achieving desired geometry.