Performance of Brazed Carbide End Mill Tool for Machining of Ti6Al4V
Titanium alloys are attractive materials for aerospace industry due to their exceptional strength to weight ratio that is maintained at elevated temperatures and their good corrosion resistance. Major applications of Titanium alloys were military aerospace industry, but since last decade the trend has now shifted towards commercial industry. On the other hand Titanium alloys are notorious for being poor thermal conductor that leads to them being difficult materials for machining. In this experimental study brazed carbide end mill of grade 5 is used for rough down milling of Ti6Al4V for large depth of cut under different combinations of parameters and application of high pressure coolant. The machining performance was evaluated in terms of tool wear, tool life, thermal crack and tool breaking. The tool wear was mostly observed at the tool tip and at bottom part of tool thermal cracks were observed which propagated with respect to time. Flank wear due to scratching of the cutting chips and diffusion wear because of high thermal stresses were observed specially at the bottom of the cutting tool. At cutting speed of 38m/min tool wear couldnt be observed due to tool failure because of fracture under high thermal stresses. It was found that maximum tool life is obtained at the speed of 25m/min, feed rate of 150mm/min and depth of cut of 10mm. In the end it was concluded that machining of Ti6Al4V is a thermally dominant process which leads to high thermal stresses in machining zone that results in increasing tool wear rate and fracture propagation.