Digital manufacturing of personalized magnesium implants through binder jet additive manufacturing and automated post machining
Mojtaba Salehi, Dennis Wee Keong Neo, Viktor Rudel, Marc Stautner, Philipp Ganser, Su Xia Zhang, Hang Li Seet, Mui Ling Sharon Nai
Abstract
While magnesium (Mg) is a promising material for personalized temporary implants, the lack of a digital manufacturing solution for Mg implants impedes its potential progress. This study introduces a hybrid manufacturing process that integrates binder jet additive manufacturing with automated dry post-machining to enable end-to-end digital manufacturing of personalized Mg implants. Spherical cap-shaped Mg implants were additively manufactured through binder jetting. These implants were placed on graphite flakes during sintering as a potential non-reactive support material, allowing unrestricted shrinkage of 15.2 % to a relative density of 87 %. Microstructural and dimensional analysis revealed consistent interconnected porous microstructures with a shrinkage distortion within ± 0.2 mm of the original digital drawing. High-speed dry milling of the sintered samples, assessed via an orthogonal cutting test, identified the optimized cutting parameters. A three-step machining process for automated 5-axis machining, along with clamping strategies, referencing, and an adaptive plug-in, were successfully implemented. The automated dry machining on binder-jet printed Mg implants resulted in an average roughness of < 1.3 µm with no defects. In summary, this work introduces a robust digital manufacturing solution to advance the transformative landscape of Mg implants and scaffolds.