Thermally Assisted Machining (TAM) of Ti6Al4V Alloys and Cutting Tool Life Assessment

Use for titanium parts and components are growing significantly to meet increasing demands by aerospace industries and their demands will continue to grow due to their excellent mechanical properties at elevated temperature and compatibility with graphite composites.  But the cost of machining of titanium alloys is high due to inherent material properties.  An alternative process called thermally assisted machining (TAM) has been developed in an attempt to make step changes in increasing machining efficiency of titanium alloy namely Ti6Al4V.  The basic TAM process involves preheating the surface of the workpiece by laser beam just ahead of the cutting tool. CSIRO in collaboration with GKN Aerospace and Boeing is investigating the mechanism of too wear and the factors that prolongs tool life in the LAM process.

While the benefits of LAM process have been demonstrated successfully the tool life can be a limiting factor for wide spread applications of this process.  Selected number of cutting tips with geometrical variations were tested at various surface preheat temperatures to study the tool life and 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 and numerical simulation and modelling were used to understand the degree of frictional heat generated and its effect on cutting tool life and hence the TAM process.  This study revealed that cutting forces were reduced and tool life had been prolonged when effective cooling by chilled air at the cutting tips is achieved.