Comparative study of basic and interleaved pixel toolpaths in wire arc additive manufacturing

<title>Abstract</title> Additive Manufacturing (AM) has become increasingly prominent in the transition from rapid prototyping to the production of end-use components, particularly in metal manufacturing, due to its ability to fabricate geometrically complex parts with high dimensional precision. Among the most widely adopted AM technologies are Powder Bed Fusion (PBF) and Directed Energy Deposition (DED), with Wire Arc Additive Manufacturing (WAAM) emerging as a promising approach because of its high deposition rate and suitability for large-scale component fabrication. Nevertheless, defects such as porosity and lack of fusion still compromise part quality, making toolpath planning a critical aspect of process optimization. In this study, the operational efficiency and metallurgical performance of the WAAM process were evaluated using two toolpath strategies, namely Basic Pixel and Interleaved Pixel. Operational efficiency was assessed in terms of printing time, travel distance, and number of stops, whereas metallurgical and geometric performance were analyzed based on microhardness, microstructure, surface quality, and dimensional conformity. The results showed that both strategies exhibited similar operational efficiency, with differences of less than 0.2%. However, the Basic Pixel strategy demonstrated superior overall performance, providing higher dimensional accuracy, improved surface quality, and lower defect incidence. In contrast, the Interleaved Pixel strategy promoted greater microstructural homogeneity and lower microhardness variation, although it exhibited higher sensitivity to thermal fluctuations. Overall, despite the microstructural advantages associated with the Interleaved Pixel strategy, the Basic Pixel strategy proved to be the most robust approach, combining improved mechanical performance, structural integrity, and geometric accuracy.