An alternative method to produce metal/plastic hybrid components for orthopedics applications

The demand for additive processes that provide components with high technological performance became overriding regardless of the application area. For medical applications, the orthopedics field—multimaterial orthoses and splints—can clearly benefit from direct additive manufacturing using a hybrid process instead of the traditional handmade manufacturing, which is slow, expensive, inaccurate, and difficult to reproduce. The ability to provide faster better orthoses, using innovative services and technologies, resulting in lower recovery times, reduced symptoms, and improved functional capacity, result in a significant impact on quality of life and the well-being of citizens. With these purposes, this work presents an integrate methodology, that includes the tridimensional (3D) scanning, 3D computer-aided design modeling, and the direct digital manufacturing of multimaterial orthoses and splints. Nevertheless, additive manufacturing of components with functional gradients, multimaterial components, e.g. metal/plastic is a great challenge since the processing factors for each one of them are very different. This paper proposes the addition of two advanced additive manufacturing technologies, the selective laser melting and the stereolithography, enabling the production of a photopolymerization of the polymer in the voids of a 3D metal mesh previously produced by selective laser melting. Based on biomimetic structures concept, this mesh is subject to a previous design optimization procedure in order to optimize its geometry, minimizing the mass involved and evidencing increased mechanical strength among other characteristics. A prototype of a hybrid additive manufacturing device was developed and its flexibility of construction, geometrical freedom, and different materials processability is demonstrated through the case study—arm orthosis—presented in this work.