CFRP (Carbon Fiber Reinforced Plastic) is a composite material formed using carbon fibers and epoxy resin matrices. It has low productivity and suffers from machining defects during precision machining. Laser machining of CFRP is associated with the problem of heat damage to the epoxy resin. EDM of CFRP can process various shapes with a shaped tool, however it has a lower material removal rate compared to laser, and the non-conductive epoxy resin layer on the surface must be removed before EDM processing. In this study, we have proposed a laser EDM hybrid machining in which CFRP was pre-processed with a laser and then post-processed by EDM. The laser pre-processing conditions were selected by adjusting the laser power and the number of repetitions to minimize thermal damage. According to EDM conditions, the size of the thermal damage area occurring in the epoxy resin, the change in the side gap, and the change in the processing time were investigated. Using the hybrid processing, micro-holes with a diameter of 150 μm were machined, and square-shaped micro-holes were also machined. To improve productivity, a multi-tool capable of processing four square shapes was manufactured, and multi-processing was performed.

Transportation industries, such as aerospace and automotive demand high efficiency using lightweight parts. Carbon Fiber Reinforced Plastics (CFRP) present promising materials for transportation industry parts due to their lightweight and highstrength properties. Forming and machining processes are required to manufacture parts from carbon fiber composite materials. The near-net shaping process forms the parts, and the final accurate shape and hole are accomplished using the machining process. However, high-strength carbon fiber chips and dust from the machining process cause cutting tool wear and low productivity. The hybrid CRD (Cutting, Routing and Drilling)/water-jet machine improves tool life and productivity because its water-jet process, employed before the mechanical machining process cuts roughly without chips and dust. In this study, the hybrid CRD/water-jet machine we developed was introduced and its machining performance was evaluated using a drilling process. The delamination factor and surface roughness of drilled holes were compared with the results from a conventional machine tool.