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CFRP has been widely used in aerospace industries because of its high strength-to-weight ratio. However, drilling CFRP laminates is difficult due to the highly abrasive nature of the carbon fibers and low thermal conductivity of CFRP. Therefore for the manufacturers it is a challenge to drill CFRP materials without causing any delamination within the high quality requirements while also considering the costs of the process. This paper will discuss the process of drilling CFRP-Al stack ups within tight tolerances using a seven axis drilling robot. All components required for drilling are integrated in the drill end-effector. The pressure foot is extended in order to clamp the work piece, and then holes are drilled. The drilling process has four steps: moving to the fast approach level, controlled drill feed, countersink depth reach and drill retract. The cutter diameter range chosen for this paper is Ø 4.0 mm and Ø 7.9 mm.

This paper will discuss the process of drilling large diameter holes within high quality requirements using a Robot positioning concept. This Robot end-effector system provides flexibility to handle different aircraft sections due to its Robot arm design. The material configuration that will be discussed in this paper is a mixed material stack of CFRP and Aluminum. The diameter range is from 7.9 mm to 15.9mm. This paper will focus on the largest diameter (Ø15.9mm). It addresses the process forces to be handled and the solutions. This paper will take an integrated look at the whole process including machine, spindle, cutting tool design and process conditions. Only this integrated view to all process related items enables running an innovative and effective process. The maximum stack size of 40 mm is another condition that requires a specific process to control the chip size to avoid an impact to the material. Here different concepts have been taken under consideration.