Defect analysis in drilling needle-punched carbon-carbon composites perpendicular to nonwoven fabrics

Abstract

Carbon-carbon composites are unique materials consisting of carbon fibers embedded in a carbonaceous matrix. Drilling of carbon-carbon composites is difficult to carry out due to the anisotropic, high specific stiffness and brittleness, nonhomogeneous inner structure of composites, and high abrasiveness of their reinforcing constituents. These typically result in defects being introduced into the workpiece and in very rapid wear development in the drilling tool. Defects are the undesired effects of machining using nonappropriate drilling parameters or worn drill. Aimed at this issue, first, the major defects caused in drilling needle-punched carbon-carbon composites are analyzed in detail. Second, the fiber fuzz factor and the ripping factor of fibers are defined to depict the drilling defects. Experiments are carried out using a conventional twist drill, and the results indicate that material structures, federates, and cutting speeds are reckoned to be the most significant factors contributing to defects.