Comparative study of titanium alloys machinability used for medical applications

Abstract

CNC machining manufacturing is critical to the development of biomedical industries, especially orthopaedic implants. Understanding a material's machinability under different cutting conditions is essential for component design as well as for optimizing the machining process. Despite their widespread use in the biomedical industry, α+β-type titanium (Ti) alloys, such as Ti-6Al-4V and Ti-6Al-7Nb, are being replaced by β or near β-type Ti alloys like Ti-13Nb-13Zr Ti alloy due to issues associated with Vanadium and Aluminium toxicity and lower modulus of elasticity. By simulating the machining of a functional cone of the hip prosthesis femoral component, this work aims to investigate some aspects of the machinability of titanium alloys: Ti-6Al-4V, Ti-6Al-7Nb, and Ti-13Nb-alloy 13Zr. Cutting forces values were registered during the tests. Using correlative microscopy, machined surfaces were examined by measuring roughness and topographic examination. According to the results obtained, the new titanium alloy Ti-13Nb-13Zr alloy presents lower cutting forces and a worse surface finish for a lower feed rate. However, when the feed rate was increased to double the initial value, this alloy had the smallest increase in Ra, compared with the other alloys under test. The effect of federate is highly significant in cutting forces and surface finish, with increases in cutting forces of 35%, 45% and 66% on cutting forces for Ti-13Nb-13Zr, Ti-6Al-4V and Ti-6Al-7Nb, respectively.