Additive manufacturing with directed energy deposition arc enables the production of large, near-net-shape metal components, yet surface waviness and geometry-dependent defects remain a major barrier to reducing post-processing effort. This study investigates a continuous helical deposition strategy combined with diameter-aware process-power scaling to stabilise the thermal regime and improve surface quality. Aluminium cylinders with diameters of 50, 100 and 150 mm were produced using the EWM React controlled short-arc process and analysed by pyrometry, thermography, 3D deviation mapping and metallography. The results show that constant parameters lead to pronounced thermal imbalance, with small diameters overheating and collapsing and large diameters undercooling and exhibiting periodic bead bulging. Scaling the wire-feed rate according to geometry-dependent cooling length establishes a quasi-stationary thermal state across all diameters, reducing radial deviation and surface waviness and increasing the degree of utilisation from 32% to nearly 90%. Compared with the conventional layer-by-layer method, the continuous helical strategy eliminates restart artefacts and produces uniform, fine-textured surfaces within the investigated diameter range. The findings demonstrate a geometry-aware approach to surface-quality improvement in aluminium directed energy deposition arc and provide a thermal framework applicable to the analysed geometries, forming a basis for future development of adaptive process control strategies.
Müller et al. (Thu,) studied this question.