A post processing technique to achieve nanofinishing for functionality enhancement of Ti-6Al-4V femoral head fabricated by Laser Powder Bed Fusion

• Published in: CIRP journal of manufacturing science and technology 2023-10, Vol.45, p.99-112
• Main Authors: Rajput, Atul Singh, Kapil, Sajan, Das, Manas
• Format: Article
• Language: English
• Subjects: Chemical etching; Femoral head; H-ECMR finishing; Post-processing; Powder bed fusion; Ti-6Al-4V
• ISSN: 1755-5817; 1878-0016
• DOI: 10.1016/j.cirpj.2023.06.006

Ti-6Al-4V alloys are extensively used as a substitution for human bones as they are biocompatible, lightweight, corrosive resistant, and have low elastic modulus. Additive Manufacturing (AM) is the best suitable process for realizing complex biomedical implants of Ti-6Al-4V alloys. However, some of the implants require a mirror-like polished surface which is typically obtained through a post-processing technique. Therefore, this work proposed a novel post-processing method to improve the surface quality of additively manufactured Ti-6Al-4V alloys. Hybrid-Electrochemical Assisted Magnetorheological (H-ECMR) finishing process utilizes the synergic action of mechanical abrasion and electrochemical reaction to enhance the surface quality of the parts without affecting their surface topography. However, the H-ECMR finishing process is effectively applicable for parts having initial surface roughness (Ra) in the sub-micron range. Hence, chemical etching is used as an intermediated process after fabricating the Ti-6Al-4 V femoral head by Laser Powder Bed Fusion (LPBF) to reduce the surface roughness in the sub-micron range. This manuscript details the working principle of the chemical etching and H-ECMR finishing process with an analysis of the impact of process parameters on the reduction in surface roughness. Moreover, Scanning Electron Microscope (SEM), Atomic Force Microscope (AFM), and optical profilometer are used to examine the change in the surface quality before and after post-processing of the LPBF fabricated femoral head. The laser scanning study confirms that the femoral head's dimensional accuracy remains intact during the H-ECMR finishing process. The wear, corrosion, and wettability tests signify that the biocompatibility of the fabricated parts is enhanced after the post-processing.