Influence of special tool geometry in drilling woven CFRPs materials

Machining processes of Carbon Fiber Reinforced Polymer (CFRP) are commonly required in order to achieve final assembly specifications. Despite the good mechanical properties of this kind of materials, they are hard to be machined due to the presence of hard particles; delamination, fiber pull-out and matrix thermal degradation are usually observed during its machining. Drilling operations are required before mechanical joining of the CFRP components. The actual interest in reducing delamination rests in the fact that it is the most serious damage found during drilling. In this work, a comparative study of three special geometries under different cutting conditions is presented. Thrust force and torque were monitoring during drilling tests and delamination extension was quantified. Results showed that a good drill tip geometry and feed rate selection is fundamental to reduce delamination damages.The funding received from the Ministry of Economy and Competitiveness of Spain under the project DPI2011-25999 and FPI subprogram with the reference BES-2012-055162 is highly appreciated