Geometry-driven co-sintering by interlocking green-state assembly of components printed via Binder Jetting

This study investigates a geometry-driven co-sintering strategy for metal Binder Jetting (BJT) to enable modular fabrication beyond conventional build-volume limitations. Complementary green parts in 17-4PH stainless steel, featuring interlocking geometries, were printed separately, manually assembled in the green state, and subsequently co-sintered without external pressure. Three prismatic joint configurations (box, dovetail, and pyramidal) and three cylindrical configurations (threaded M10, threaded M14, and conical) were systematically analyzed as a function of the nominal interface offset. Dimensional measurements and local split thickness analysis revealed that the residual interface opening after sintering is consistently lower than the imposed design offset, indicating shrinkage-assisted partial gap closure during densification. The evolution of the split distribution demonstrated a geometry-dependent behavior: interlocking prismatic joints exhibited higher sensitivity to assembly misalignment and local constraint effects, while axisymmetric cylindrical configurations showed more uniform shrinkage accommodation. The proposed approach combines mechanical interlocking in the green state with metallurgical bonding during sintering, providing a framework for modular BJT assemblies and offering a promising pathway to simplifying the depowdering phase and overcoming build-size limitations. While mechanical characterization of the joints is required to assess structural load-bearing capability, the present work establishes the geometrical and process foundations necessary for controlled co-sintered assemblies in BJT.