Inter-Printhead Bonding Strategies for Same-Material Collective Additive Manufacturing in FDM 3D Printing

Collective additive manufacturing (CoAM) distributes a single part across multiple coordinated printheads to reduce makespan and enable larger build volumes. While prior work has focused on scheduling and partitioning strategies, the mechanical implications of inter-printhead bonding remain underexplored. This study proposes and evaluates six inter-printhead bonding strategies. Overlap, Finger joint, Ironing, Interlock, Interlace, and Stochastic against two baselines (Inline and 30° Chunk) using PLA tensile specimens. Compared to a part printed using a single printhead, results showed relative ultimate tensile strength of Interlace (92.5%), Ironing (90.4%), Chunk (89.2%), Stochastic (89.0%), and Inline (87.8%), forming a top-performing group with minimal strength differences. Stochastic and Chunk exhibited markedly higher elongation, 6.43% and 8.98% at break respectively, compared to other methods. The findings demonstrate multiple viable bonding strategies for CoAM and highlight the bidirectional dependence between process planning and bonding design.