Heat sink approach to improve machinability in dry drilling of titanium alloys

While it is known that use of coolant and lubricants in machining of titanium alloys help to improve machinability, the coolants are often poured on cutting zones to carry the heat while they flow away. In the absence of positive mechanism to drive the coolants away, the heat dissipation does not occur effectively. This work therefore, proposes a novel application of heat sink approach for dissipation of heat during drilling of titanium alloys. In this work, highly conductive copper plates are glued to the titanium plates being drilled either on the sides or at the bottom. The copper plates thus form Butt jointed or Lap jointed heat sink. Extensive experimentation has been performed while measuring thrust, torque and temperature during drilling to evaluate the effectiveness of heat sink strategies. It is observed that the Butt jointed heat sink reduced the thrust by 15% and torque by 26% over the dry titanium plates without a heat sink at the cutting speed of 35 m/min. Cutting temperature is also reduced by 58% by the use of Butt jointed heat sink over the Lap jointed heat sink.