Abstract
This paper describes the state of the art technologies associated with coolant in machining difficult-to-machine materials. Using high pressure coolant is one of solutions for high speed and high efficiency machining of difficult-to-machine materials. High cooling ability of high pressure coolant reduces cutting temperature, resulting in the reduction of tool wear, the extension of tool life and the improvement of the integrity of finished surface. High pressure coolant can broke a produced chip. The length of a broken chip decreases with increasing pressure of coolant. Thus, drilling of a deep hole using high pressure coolant can be conducted without pecking. When the high pressure coolant is not available, a jet of low pressure coolant supplied from a nozzle very close to the tool tip is effective for reducing tool wear. Cryogenic machining with liquid nitrogen or liquid carbon dioxide may be an alternative of machining with high pressure coolant.
