US Patent 7802947 Cutting tool insert having internal microduct for coolant

A cutting tool insert includes: a body defining a rake face, a flank face, and a cutting edge at an intersection of the rake and flank faces; and a cooling microduct within the body. A portion of the microduct extends along the cutting edge not more than 0.5 millimeter from the rake face, and not more than 0.5 millimeter from the flank face. The microduct has a cross-sectional area of not more than 1.0 square millimeter. The microduct is adapted to permit the flow of a coolant therethrough to transfer heat away from the cutting edge and extend the useful life of the insert. Secondary conduits having cross-sectional area no larger than 0.004 square millimeter may communicate between the microduct and the rake and/or flank face to exhaust coolant behind the cutting edge and further enhance cooling.