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This paper describes the principles of a new method to compensate for tool wear when drilling in complex materials such as Carbon Fibre Reinforced Plastics (CFRP), Carbon Fibre Reinforced Plastics / Titanium (CFRP/Ti) and Carbon Fibre Reinforced Plastics / Alloy (CFRP/AI) stacks. A reliable and repeatable hole quality is essential, especially in automatic drilling applications with robots or gantries. The method combines the unique feature to dynamically adjust the drilling diameter in very small steps in an Orbital drilling End-effector and a new type of software algorithm to predict and compensate for the tool wear in different materials. With this method a large number of holes can be drilled without changing the cutting tool, and a Cpk value of more than 2,5 can be achieved.

This paper deals with orbital drilling of sandwich constructions for space applications. Sandwich constructions for space applications are typically made up of thin layers of carbon fiber composite skins separated by an aluminum or carbon honeycomb core. Drilling holes in such structures is required for assembly purposes. A common and significant problem occurs when drilling such structures with conventional methods, namely delamination on the exit side of the composite layers. In this study orbital drilling is investigated as a means of eliminating delaminations and other frequently encountered problems with conventional drilling of laminated composite structures. Holes of different sizes were drilled in sandwich panels using orbital drilling. Both automatic (CNC) and semi-automatic (portable) orbital drilling were investigated. Damage in the vicinity of the holes was assessed by means of microscopic evaluation.