Post-processing of additively manufactured metallic bioimplants: Approaches, challenges and future trends

Additive manufacturing (AM) is an emerging technology grabbing massive attention of industries due to the flexibility in producing parts with any degree of complexity. Nowadays, biomedical industries are highly reliant on AM technology for accomplishing bioimplant fabrication based on patient-specific requirements. SS316L, Ti6Al4V, and Co–Cr are the materials widely used for bioimplant fabrication using metal AM. Further, mass customization possibilities with minimum wastage of raw material add to the supremacy of AM over other manufacturing methods. However, components produced by AM exhibit defects like surface irregularities, voids, porosities, and cracks. In order to overcome such challenges and enhance the quality of fabricated implants, industries have to rely on various post-processing methods. The existing post-processing variants can be categorized into surface post-treatment methods and thermal processing methods. The former utilizes sources such as laser, chemicals, abrasives, or mechanical forces to achieve desired surface quality, whereas the latter involves heat treatment operations on the bulk material for removing mechanical anisotropy. Each of these established post-processing methods is associated with several inherent bright sides and limitations while considering biomedical standards into account. Nevertheless, AM process is quite expensive and adoption of a secondary post-processing method can incur additional expenses which leads to increased cost of implant production. In this context, future trends are directed toward the deployment of in situ online monitoring and machine learning-assisted techniques to transform the bioimplant production to acceptable standards with reduced cost. Thus, additively manufactured bioimplants can soon conquer the traditional manufacturing techniques through effective evolution of post-processing strategies that can ultimately ensure superior functionality and durability of bioimplants.