Investigation on magnetic polishing characteristics of metal additive manufactured Ti-6Al-4V

The metal additive manufacturing (AM) of Ti-6Al-4V is expected to fabricate artificial replacement products with high efficiency. A hybrid additive manufacturing machine that combines with a machining centre was developed in the recent years. A desired shape can be obtained but generating a high-accuracy surface roughness is difficult. However, these products need a high surface quality. These products are generally polished by hand work, resulting in the deterioration of the shape accuracy or increase in the non-machining time. Therefore, this study develops a magnetic polishing method that can polish Ti alloy on a hybrid metal AM machine. A workpiece made of Ti-6Al-4V is fabricated in the metal AM machine, and is ball end-milled to a flat shape. The workpiece is then magnetically polished on the machining centre. The pressing force, polished amount, and surface roughness are measured. Moreover, the Preston constant of the additive manufactured Ti-6Al-4V is calculated. A typical Ti-6Al-4V is also magnetically polished, with its Preston constant calculated. In summary, the Preston constant of the additive manufactured Ti-6Al-4V was approximately 0.78 times smaller than that of the typical Ti-6Al-4V.