Assessment of the Influence of Machining Modes on the Surface Roughness of Implants Made of Ultrafine-Grain and Coarse-Grain Titanium

Currently, special attention is being paid to the research of ultrafine-grain (UFG) titanium materials obtained by methods of intensive plastic deformation. These technologies make it possible to form a submicron structure and thereby change the complex of mechanical and physical properties that determine the behavior of the material in the manufacture of parts. In this paper, a comparative study of the machinability of Grade 4 titanium in two structural states, ultrafine—grain (UFG) and coarse-grain (CG), is performed. The influence of turning modes on the surface roughness parameters is considered as one of the main indicators of the quality of the treated layer. Experimental data show that UFG state in most cases provides lower values of Ra compared to CG state. The differences are especially evident with increased cutting speed, when the process becomes more stable and the surface quality is more reproducible. The minimum roughness value (Ra) of 0.29±0.03 microns is obtained for UFG titanium at a cutting speed (V) of 27 m/min, feed (S) of 0.06 mm/rpm and a cutting depth (t) of 0.3 mm. The obtained results indicate the possibility of increasing turning productivity while maintaining surface quality requirements. This is important in the manufacture of critical parts, including medical implant blanks, where the stability of the surface layer parameters directly affects the operational characteristics of the product.