Heated printhead binder jetting of 316 L stainless steel using a low-saturation aqueous PVA binder

Binder jetting is an additive manufacturing process in which a liquid binder is selectively deposited onto a powder bed, layer by layer, to form a green part for subsequent sintering. While it offers design flexibility and scalability, most commercial systems employ resin-based binders that release volatile organic compounds and leave carbon residues. In this study, a customised binder jetting system was developed to process 316 L stainless steel using, for the first time, a heated printhead optimised for a non-resin aqueous binder consisting of 1 wt% polyvinyl alcohol (PVA) in deionised water, applied solely through the printhead without pre-blending into the powder.

Printhead heating enhanced droplet jettability and wettability, enabling low binder saturation (20%) while achieving green part compressive strength of 2.72 MPa, sufficient for safe handling, and minimal shrinkage (≤15.08%). The combined effects of layer thickness and sintering temperature were investigated, with optimal results obtained at 80 μm layer thickness and 1450 °C vacuum sintering. Under these conditions, parts achieved relative densities of 98.66 ± 0.20% (Archimedes) and 99.07 ± 0.12% (cross-section), 156.3 HV hardness, and 517.46 MPa tensile strength without hot isostatic pressing. These results demonstrate competitive performance with reduced environmental impact, highlighting the potential of aqueous binder jetting with a heated printhead for more sustainable metal additive manufacturing.