Fabrication of cooling holes using laser machining and ultrasonic machining

A method of machining cooling holes, the method comprising:

• providing a ceramic airfoil in which cooling holes are to be formed, wherein the cooling holes once formed each define distinct first and second sections, the ceramic airfoil being secured in a fixture that is mounted in a first chuck of a first machine;
• generating a solid form model of each of the cooling holes from a difference between a first computerized 3-dimensional model of the workpiece with the cooling holes and a second computerized 3-dimensional model of the workpiece without the cooling holes;
• partitioning the solid form model of each of the cooling holes into cross-sections;
• in the first machine, using a laser to drill through-holes in the ceramic airfoil by scanning the laser across the ceramic airfoil along a toolpath in each of the cross-sections to cause removal of material of the ceramic airfoil layer-by-layer, each of the through-holes being spatially common to the first and second sections of a respective one of the cooling holes;
• reducing error of a position of the ceramic airfoil relative to the fixture due to manufacturing imperfections by, after drilling the through-holes, removing the fixture with the ceramic airfoil secured therein from the first machine and, without removing the ceramic airfoil from the fixture, mounting the fixture in a second chuck of a second machine, the first chuck and the second chuck being of common type such that the fixture is securable into both the first chuck and the second chuck, with the fixture mounted in the second chuck of the second machine, determining a compensated tool position, and performing ultrasonic machining based upon the compensated tool position;
• in the second machine, using the ultrasonic machining to expand a portion of each of the through-holes to form the second section;
• and draining an abrasive slurry through the through-holes during the ultrasonic machining.