An overview of high-speed machining of titanium alloys

Abstract

Titanium alloys have been widely used in the aerospace, biomedical and automotive industries because of their good strength-to-weight ratio and superior corrosion resistance. However, it is very difficult to machine them due to their poor machinability, which has led many large companies to invest much in developing techniques to minimize machining cost. During machining of titanium alloys, their poor thermal conductivity results in the higher temperature closer to the cutting edge, and there exists strong affinity between the tool and workpiece material. When machining titanium alloys with the conventional tools, the wear rate progresses rapidly, and the cutting speed is generally difficult to be over 60m/min. Other types of tool materials, including ceramic, diamond, and cubic boron nitride (CBN), are highly reactive with titanium alloys at higher temperature, and consequently they are not effective to be used in HSM of titanium alloys. The binder-less CBN (BCBN) tools, which neither have any binder nor a sintering agent or a catalyst, have a remarkably longer tool life than conventional CBN inserts under all cutting conditions (up to 400m/min). The BCBN appears to become a new cutting tool material for HSM of titanium alloys both economically and functionally. In order to get deeper understanding of HSM of titanium alloys, the generation of mathematical models is essential. Therefore, analytical models are needed to be established to predict the machining parameters for HSM of titanium alloys. This paper aims to give an overview of recent developments in machining and HSM of titanium alloys, geometrical modeling of HSM and cutting force models for HSM of titanium alloys.