Ultrasonic machining an aperture in a workpiece

A method for machining a workpiece, comprising:

• forming an aperture in the workpiece using a machining system comprising an ultrasonic machining device, a slurry delivery device and a controller, the slurry delivery device comprising a passage that extends within the ultrasonic machining device to a tip of the ultrasonic machining device, the forming of the aperture comprising delivering a slurry to an interface between the ultrasonic machining device and the workpiece using the slurry delivery device, and transmitting ultrasonic vibrations into the slurry using the ultrasonic machining device;
• monitoring a feedback parameter during the forming of the aperture using the controller;
• and
• adaptively adjusting a slurry delivery parameter for the slurry delivery device during the forming of the aperture based on the feedback parameter using the controller;
• wherein the slurry is delivered to the interface through the passage during the forming of the aperture, and the slurry is removed from the interface through the passage during the forming of the aperture.