Machinability analysis in drilling and milling for carbon fiber reinforced epoxy (CFRE) composite

CFRE composites are widely applied to relatively simple sheet forms; however, when applied to actual products in complex forms, a finishing process is frequently required in conjunction with machining. Nevertheless, studies on the machinability of the CFRE composite in manufacturing actual products are still relatively rare. This study analyzed the machinability of CFRE composites in drilling and milling processes. The cutting processes involving drilling and milling methods were performed at various machining parameters. Key drilling findings indicate that flat endmills provide superior entry and bottom surfaces compared to twist drills. Increasing the number of cutting edges from two to four flutes enhances cutting ability, although all tools generate delamination at the exit of the through hole. While tool type did not significantly affect side-surface texture, optimal dimensional accuracy in 0.007 mm was achieved using a 4-flute flat-end mill with a cutting speed of 50 m/min and a feed rate of 80 mm/min. In side milling, surface characteristics were identical for both up-milling and down-milling; however, the down-milling method is recommended for parallel cutting to minimize burrs. For pocket milling, burrs predominantly formed on the lateral margin. This burr formation was intensified by elevated feed rates, indicating that lower feed rates yield better surface quality.