TITANIUM-ALLOYS AND THEIR MACHINABILITY - A REVIEW

Although there have been great advances in the development of cutting tool materials which have significantly improved the machinability of a large number of metallic materials, including cast irons, steels and some high temperature alloys such as nickel-based alloys, no equivale nt development has been made for cutting titanium alloys due primarily to their peculiar characteristics. This paper reviews the main proble ms associated with the machining of titanium as well as tool wear and the mechanisms responsible for tool failure. It was found that the str aight tungsten carbide (WC/Co) cutting tools continue to maintain thei r superiority in almost all machining processes of titanium alloys, wh ilst CVD coated carbides and ceramics have not replaced cemented carbi des due to their reactivity with titanium and their relatively low fra cture toughness as well as the poor thermal conductivity of most ceram ics. This paper also discusses special machining methods, such as rota ry cutting and the use of ledge tools, which have shown some success i n the machining of titanium alloys. (C) 1997 Elsevier Science S.A.