High Speed Removal of Ti6Al4V Using Thermally Assisted Machining

Titanium alloys are one of the most important alloy systems used for aerospace component and their uses will continue to grow due to their excellent mechanical properties at elevated temperature and compatibility with graphite composites.  A substantial amount of the cost of titanium components is attributed to machining which is mainly caused by poor machinability of the titanium alloy in conventional machining process.  An alternative process called thermally assisted machining (TAM) is currently being investigated by an industry team for the Joint Strike Fighter program in Australia led by CSIRO in an attempt to make step changes in increasing machining efficiency of titanium alloy namely Ti6Al4V.  This collaborative project will investigate some underlying aspects of the process variables, which are essential to incorporate into a cutting cell.  The basic process involves dry milling without any lubrication utilising an appropriate shape and power of laser beam to preheat the surface of the work piece just ahead of the cutting tool.

Selected numbers of cutting tips were tested at various laser powers to study the cutting behaviour of Ti6Al4V alloy.  High speed video camera was utilised to study the swarf formation and mechanisms by which built-up-edge (BUE) is formed.  Thermal imaging camera was used to understand the degree of frictional heat generated and its effect on cutting process.  This study revealed that high speed milling is possible provided an accurate level of preheating is maintained.  Various techniques were utilised to collect accurate preheat temperatures when the work piece is subjected to laser hear heat.  Cutting forces were also recorded in an attempt to predict tool degradation.  This study highlights various aspects of important parameters for TAM process.