Sustainable machining of titanium alloys: A critical review

The three main pillars of sustainability are the society, the environment, and the economy (people, planet, and profit). The key drivers that sustain these three pillars are energy and resource efficiency, a clean and ‘green’ environment that incorporates effective waste reduction and management, and finally cost-effective production. Sustainable manufacturing implies technologies and/or techniques that target these key drivers during product manufacture. Because of the effort and costs involved in the machining of titanium and its alloys, there is significant scope for improved sustainable manufacturing of these materials. Titanium and its alloys are extensively used for specialized applications in aerospace, medical, and general industry because of their superior strength-to-weight ratio and corrosion resistance. They are, however, generally regarded as difficult-to-machine materials. This article presents an overview of previous and current work and trends as regards to sustainable machining of titanium and its alloys. This article focuses on reviewing previous work to improve the sustainable machining of titanium and its alloys with specific reference to the selection of optimum machining conditions, effect of tool materials and geometry, implementing advanced lubrication and/or cooling techniques, and employing advanced and hybrid machining strategies. The main motivation is to present an overview of the current state of the art to discuss the challenges and to suggest economic and environment-friendly ways for improving the machinability of titanium and its alloys.