Non-heat source forming technology of binder jetting metal powder and its post-treatment process

The binder jetting (BJ) forming process is an additive manufacturing method based on discrete stacking and micro-jetting technology. It has the advantages of low cost and high degree of automation; however, at the present stage, the metal forming process involves the heat source, which leads to high molding and maintenance costs. To solve this problem, non-heat source forming technology of binder jetting metal powder was proposed. Polyvinyl alcohol was used as the adhesive agent in the powder to reduce the heat-setting process in the metal-forming process. Droplet penetration simulations were conducted using COMSOL Multiphysics. The relationship between the penetration thickness and printhead moving speed was investigated. The BJ optimum printing process parameters and the optimum post-treatment parameters were identified: 115% binder saturation, 0.18 mm layer thickness, and 100:1 metal-PVA powder mass ratio; degreasing at 350 °C for 2 h and pre-sintering 800 °C for 90 min (nitrogen atmosphere), final sintering at 1380 °C for 90 min (vacuum atmosphere). The tensile strength of the metal specimen reached 323 MPa, and the density reached 85.6%.