Metal additive manufacturing with powder and wire feedstocks

Metal additive manufacturing (AM) eliminates traditional design and production limitations, enabling the creation of complex geometries layer-by-layer from bulk material. The form of the material feedstock has a significant influence on design, efficiency, and process performance. A dichotomy is quickly emerging between powdered metal and wire across all AM technologies for metallic products. This article presents a unique perspective on powder bed fusion and laser-directed energy deposition (DED), two of the most mature metal AM processes, and wire-based electric arc DED, a promising newcomer. Despite its many advantages, confidence in wire Arc-DED lags behind powder processes due to their widespread familiarity. To accelerate research and adoption of wire-based Arc-DED, it is essential to appreciate the maturity of its foundational welding processes, increase metallurgical understanding, and optimise processing. To that end, a literature overview of physical characteristics, equipment availability, and process maturity for wire and powder is undertaken. The advantages and critical issues of wire-based Arc-DED are explicitly compared to those of powder-based DED, with detailed trade-offs in process, equipment, design, and safety drawn from firsthand knowledge. Critical issues in material properties and defects related to the nature of the feedstock are also examined, and wire-based innovations are discussed.