Abstract: The present invention provides a drilling apparatus and a method thereof capable of providing an adjustable active backup force to a composite workpiece to effectively reduce the delamination of the workpiece during drilling such that the application of the active backup force in terms of its force magnitude and its application location on the workpiece can adjustably counter the drill thrust force to retard the onset of delamination growth and reduce delamination damage at the drill exit in the workpiece, in particular in situation where large feed rate with short cycle time is desired for drilling of composite materials. A critical drill thrust force of the drilling apparatus and the method of the present invention is advantageously obtained in relation to said active backup force and the application of the active backup force to reduce the crack propagation of the delamination occurred in the composite workpiece.

Abstract: The present invention provides a drilling apparatus and a method thereof capable of providing an adjustable active backup force to a composite workpiece to effectively reduce the delamination of the workpiece during drilling such that the application of the active backup force in terms of its force magnitude and its application location on the workpiece can adjustably counter the drill thrust force to retard the onset of delamination growth and reduce delamination damage at the drill exit in the workpiece, in particular in situation where large feed rate with short cycle time is desired for drilling of composite materials. A critical drill thrust force of the drilling apparatus and the method of the present invention is advantageously obtained in relation to said active backup force and the application of the active backup force to reduce the crack propagation of the delamination occurred in the composite workpiece.