A Study on Qualitative and Quantitative Characterization of Machining Quality of Aerospace Composite Structures

Machining CFRP composites generally create defects in machined surfaces which are more irregular than those given by metal machining. Minimizing and controlling the occurrence of damage is a crucial task. To archive that, quantifying damage and correlating it to cutting parameters, as well as mechanical behavior is significant. This study investigates the influences of machining parameters such as spindle speed and feed speed on the ten-point max, R_z. This roughness parameter is recommended to adopt for quantifying the machining quality of CFRPs instead of R_a. Machining defects are identified by SEM observation. R_z values are determined in both longitudinal and perpendicular directions to the machined surfaces. The results show that the combination between high spindle speed and low feed speed can seriously create damage levels. Moreover, it is proved that R_z can well reflect damage evolution, qualitatively identified by SEM observation. This can be concluded that R_z can be a good indicator to quantify machining damage of composite materials instead of using expensive systems which are difficult to be afforded whenever.